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Siegel, Joshua S., Gordon L. Shulman e Maurizio Corbetta. "Measuring functional connectivity in stroke: Approaches and considerations". Journal of Cerebral Blood Flow & Metabolism 37, n.º 8 (25 de maio de 2017): 2665–78. http://dx.doi.org/10.1177/0271678x17709198.
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Recent research has demonstrated the importance of global changes to the functional organization of brain network following stroke. Resting functional magnetic resonance imaging (R-fMRI) is a non-invasive tool that enables the measurement of functional connectivity (FC) across the entire brain while placing minimal demands on the subject. For these reasons, it is a uniquely appealing tool for studying the distant effects of stroke. However, R-fMRI studies rely on a number of premises that cannot be assumed without careful validation in the context of stroke. Here, we describe strategies to identify and mitigate confounds specific to R-fMRI research in cerebrovascular disease. Five main topics are discussed: (a) achieving adequate co-registration of lesioned brains, (b) identifying and removing hemodynamic lags in resting BOLD, (c) identifying other vascular disruptions that affect the resting BOLD signal, (d) selecting an appropriate control cohort, and (e) acquiring sufficient fMRI data to reliably identify FC changes. For each topic, we provide guidelines for steps to improve the interpretability and reproducibility of FC-stroke research. We include a table of confounds and approaches to identify and mitigate each. Our recommendations extend to any research using R-fMRI to study diseases that might alter cerebrovascular flow and dynamics or brain anatomy.
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Yan, Chao-gan, Qingyang Li e Lei Gao. "PRN: a preprint service for catalyzing R-fMRI and neuroscience related studies". F1000Research 3 (22 de dezembro de 2014): 313. http://dx.doi.org/10.12688/f1000research.5951.1.
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Sharing drafts of scientific manuscripts on preprint hosting services for early exposure and pre-publication feedback is a well-accepted practice in fields such as physics, astronomy, or mathematics. The field of neuroscience, however, has yet to adopt the preprint model. A reason for this reluctance might partly be the lack of central preprint services for the field of neuroscience. To address this issue, we announce the launch of Preprints of the R-fMRI Network (PRN), a community funded preprint hosting service. PRN provides free-submission and free hosting of manuscripts for resting state functional magnetic resonance imaging (R-fMRI) and neuroscience related studies. Submissions will be peer viewed and receive feedback from readers and a panel of invited consultants of the R-fMRI Network. All manuscripts and feedback will be freely available online with citable permanent URL for open-access. The goal of PRN is to supplement the “peer reviewed” journal publication system – by more rapidly communicating the latest research achievements throughout the world. We hope PRN will help the field to embrace the preprint model and thus further accelerate R-fMRI and neuroscience related studies, eventually enhancing human mental health.
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Yan, Chao-gan, Qingyang Li e Lei Gao. "PRN: a preprint service for catalyzing R-fMRI and neuroscience related studies". F1000Research 3 (19 de agosto de 2015): 313. http://dx.doi.org/10.12688/f1000research.5951.2.
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Sharing drafts of scientific manuscripts on preprint hosting services for early exposure and pre-publication feedback is a well-accepted practice in fields such as physics, astronomy, or mathematics. The field of neuroscience, however, has yet to adopt the preprint model. A reason for this reluctance might partly be the lack of central preprint services for the field of neuroscience. To address this issue, we announce the launch of Preprints of the R-fMRI Network (PRN), a community funded preprint hosting service. PRN provides free-submission and free hosting of manuscripts for resting state functional magnetic resonance imaging (R-fMRI) and neuroscience related studies. Submitted articles are openly discussed and receive feedback from readers and a panel of invited consultants from the R-fMRI Network. All manuscripts and feedback are freely accessible online with citable permanent URL for open-access. The goal of PRN is to supplement the peer reviewed journal publication system – by more rapidly communicating the latest research achievements throughout the world. We hope PRN would help the field to embrace the preprint model and thus further accelerate R-fMRI and neuroscience related studies, eventually enhancing human mental health.
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Mousavi, S., A. Massot Tarrus, F. Bihari, S. Hayman Abello, B. Hayman Abello e S. Mirsattari. "fMRI for language: how can it replace the Wada test?" Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 42, S1 (maio de 2015): S27. http://dx.doi.org/10.1017/cjn.2015.133.
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Background: The goal of our project is to assess the feasibility of replacing the invasive Wada test considered as the gold standard with non-invasive fMRI test for assessment of language dominance preoperatively. Methods: fMRI test with three language paradigm tasks (verb generation, sentence completion and naming) were conducted on our cohort of patients. fMRI laterality indices (LI) were then defined as a ratio (L-R)/(L+R) between the number of activated voxels in the left and right ROIs for Anterior Language Area (ALA) and Posterior Language Area (PLA). fMRI results were divided into the right (LI < -0.2), left (LI > 0.2) or bilateral (-0.2 < LI <0.2) hemispheric language dominance and compared to the results of the Wada test. Results: 28 patients were studied. The concordance rate between Wada and fMRI tests for the ALA and PLA was 68.2% and 52.2% for sentence completion; 56% and 52% for verb generation and 25% and 35% for naming paradigm, respectively. Conclusions: Sentence completion and verb generation fMRI paradigms showed higher concordance with Wada test than naming paradigm. The higher discordance between the Wada test and fMRI was related to bilateral results suggestive of less stringent thresholds used for either test.
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Mousavi, S., A. Massot Tarrus, F. Bihari, S. Hayman Abello, B. Hayman Abello e S. Mirsattari. "Concordance rate between Wada and fMRI tests for visual memory assessment of patients with medically intractable temporal lobe epilepsy". Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 42, S1 (maio de 2015): S10. http://dx.doi.org/10.1017/cjn.2015.74.
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Background: There is not enough evidence to prove either invasive Wada or non-invasive fMRI test predicts postoperative memory changes more accurately in patients with refractory temporal lobe epilepsy (TLE). In this study, concordance between fMRI and Wada test for postoperative assessment of visual memory is investigated. Methods: fMRI test with a novel scene-encoding task were conducted on our cohort of patients. fMRI laterality indices (LI) were then defined as a ratio (L-R)/(L+R) between the number of activated voxels in the left and right of two regions: hippocampus+parahippocampus (Region A) and temporal lobe - (hippocampus+parahippocampus) (Region B). fMRI results were divided into the right (LI < -0.2), left (LI > 0.2) or bilateral (-0.2 < LI <0.2) hemispheric memory dominance and compared to the results of the Wada test. Results: 19 patients were studied (14 left TLE, 3 right TLE and 2 bilateral TLE). The concordance rate between Wada and fMRI tests was 36.8% and 42.1% for regions A and B. Conclusions: Based on the results, the concordance rate between the Wada test and the fMRI test is not high. As a future work, we will investigate the correlation of each test to postoperative memory outcome.
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Yan, Chao-Gan, Xiao Chen, Le Li, Francisco Xavier Castellanos, Tong-Jian Bai, Qi-Jing Bo, Jun Cao et al. "Reduced default mode network functional connectivity in patients with recurrent major depressive disorder". Proceedings of the National Academy of Sciences 116, n.º 18 (12 de abril de 2019): 9078–83. http://dx.doi.org/10.1073/pnas.1900390116.
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Major depressive disorder (MDD) is common and disabling, but its neuropathophysiology remains unclear. Most studies of functional brain networks in MDD have had limited statistical power and data analysis approaches have varied widely. The REST-meta-MDD Project of resting-state fMRI (R-fMRI) addresses these issues. Twenty-five research groups in China established the REST-meta-MDD Consortium by contributing R-fMRI data from 1,300 patients with MDD and 1,128 normal controls (NCs). Data were preprocessed locally with a standardized protocol before aggregated group analyses. We focused on functional connectivity (FC) within the default mode network (DMN), frequently reported to be increased in MDD. Instead, we found decreased DMN FC when we compared 848 patients with MDD to 794 NCs from 17 sites after data exclusion. We found FC reduction only in recurrent MDD, not in first-episode drug-naïve MDD. Decreased DMN FC was associated with medication usage but not with MDD duration. DMN FC was also positively related to symptom severity but only in recurrent MDD. Exploratory analyses also revealed alterations in FC of visual, sensory-motor, and dorsal attention networks in MDD. We confirmed the key role of DMN in MDD but found reduced rather than increased FC within the DMN. Future studies should test whether decreased DMN FC mediates response to treatment. All R-fMRI indices of data contributed by the REST-meta-MDD consortium are being shared publicly via the R-fMRI Maps Project.
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Stocco, Andrea. "Coordinate-Based Meta-Analysis of fMRI Studies with R". R Journal 6, n.º 2 (2014): 5. http://dx.doi.org/10.32614/rj-2014-020.
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Liebel, Spencer W., Uraina S. Clark, Xiaomeng Xu, Hannah H. Riskin-Jones, Brittany E. Hawkshead, Nicolette F. Schwarz, Donald Labbe, Beth A. Jerskey e Lawrence H. Sweet. "An FMRI-Compatible Symbol Search Task". Journal of the International Neuropsychological Society 21, n.º 3 (março de 2015): 231–38. http://dx.doi.org/10.1017/s1355617715000144.
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AbstractOur objective was to determine whether a Symbol Search paradigm developed for functional magnetic resonance imaging (FMRI) is a reliable and valid measure of cognitive processing speed (CPS) in healthy older adults. As all older adults are expected to experience cognitive declines due to aging, and CPS is one of the domains most affected by age, establishing a reliable and valid measure of CPS that can be administered inside an MR scanner may prove invaluable in future clinical and research settings. We evaluated the reliability and construct validity of a newly developed FMRI Symbol Search task by comparing participants’ performance in and outside of the scanner and to the widely used and standardized Symbol Search subtest of the Wechsler Adult Intelligence Scale (WAIS). A brief battery of neuropsychological measures was also administered to assess the convergent and discriminant validity of the FMRI Symbol Search task. The FMRI Symbol Search task demonstrated high test–retest reliability when compared to performance on the same task administered out of the scanner (r=.791; p<.001). The criterion validity of the new task was supported, as it exhibited a strong positive correlation with the WAIS Symbol Search (r=.717; p<.001). Predicted convergent and discriminant validity patterns of the FMRI Symbol Search task were also observed. The FMRI Symbol Search task is a reliable and valid measure of CPS in healthy older adults and exhibits expected sensitivity to the effects of age on CPS performance. (JINS, 2015, 22, 1–8)
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Fontoura, Denise Ren da, Daniel de Moraes Branco, Mauricio Anés, Jaderson Costa da Costa e Mirna Wetters Portuguez. "Language brain dominance in patients with refractory temporal lobe epilepsy: a comparative study between functional magnetic resonance imaging and dichotic listening test". Arquivos de Neuro-Psiquiatria 66, n.º 1 (março de 2008): 34–39. http://dx.doi.org/10.1590/s0004-282x2008000100009.
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PURPOSE: To identify brain dominance for language functions with DLT and correlate these results with those obtained from fMRI in patients suffering from intractable temporal lobe epilepsy. METHOD: This study reports on 13 patients who underwent pre-surgical epileptic evaluation between April and October 2004 at the Epilepsy Surgery Program, Hospital Sao Lucas, PUCRS. In DLT, dominance was assessed through a consonant-vowel task, whereas in fMRI patients performed a verb generation task. RESULTS: Our results identified a correlation between the fMRI lateralization index and the DLT ear predominance index and reply difference index (r=0.6, p=0.02; Pearson Correlation Coefficient), showing positive correlation between results obtained from fMRI and DLT. CONCLUSION: DLT was found to significantly correlate with fMRI. These findings indicate that DLT (a non-invasive procedure) could be a useful tool to evaluate language brain dominance in pre-surgical epileptic patients as it is cheaper to perform than fMRI.
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Roder, Constantin, Edyta Charyasz-Leks, Martin Breitkopf, Karlheinz Decker, Ulrike Ernemann, Uwe Klose, Marcos Tatagiba e Sotirios Bisdas. "Resting-state functional MRI in an intraoperative MRI setting: proof of feasibility and correlation to clinical outcome of patients". Journal of Neurosurgery 125, n.º 2 (agosto de 2016): 401–9. http://dx.doi.org/10.3171/2015.7.jns15617.
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OBJECTIVE The authors' aim in this paper is to prove the feasibility of resting-state (RS) functional MRI (fMRI) in an intraoperative setting (iRS-fMRI) and to correlate findings with the clinical condition of patients pre- and postoperatively. METHODS Twelve patients underwent intraoperative MRI-guided resection of lesions in or directly adjacent to the central region and/or pyramidal tract. Intraoperative RS (iRS)–fMRI was performed pre- and intraoperatively and was correlated with patients' postoperative clinical condition, as well as with intraoperative monitoring results. Independent component analysis (ICA) was used to postprocess the RS-fMRI data concerning the sensorimotor networks, and the mean z-scores were statistically analyzed. RESULTS iRS-fMRI in anesthetized patients proved to be feasible and analysis revealed no significant differences in preoperative z-scores between the sensorimotor areas ipsi- and contralateral to the tumor. A significant decrease in z-score (p < 0.01) was seen in patients with new neurological deficits postoperatively. The intraoperative z-score in the hemisphere ipsilateral to the tumor had a significant negative correlation with the degree of paresis immediately after the operation (r = −0.67, p < 0.001) and on the day of discharge from the hospital (r = −0.65, p < 0.001). Receiver operating characteristic curve analysis demonstrated moderate prognostic value of the intraoperative z-score (area under the curve 0.84) for the paresis score at patient discharge. CONCLUSIONS The use of iRS-fMRI with ICA-based postprocessing and functional activity mapping is feasible and the results may correlate with clinical parameters, demonstrating a significant negative correlation between the intensity of the iRS-fMRI signal and the postoperative neurological changes.
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Horner, Aidan J., e Richard N. Henson. "Incongruent Abstract Stimulus–Response Bindings Result in Response Interference: fMRI and EEG Evidence from Visual Object Classification Priming". Journal of Cognitive Neuroscience 24, n.º 3 (março de 2012): 760–73. http://dx.doi.org/10.1162/jocn_a_00163.
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Stimulus repetition often leads to facilitated processing, resulting in neural decreases (repetition suppression) and faster RTs (repetition priming). Such repetition-related effects have been attributed to the facilitation of repeated cognitive processes and/or the retrieval of previously encoded stimulus–response (S-R) bindings. Although previous research has dissociated these two forms of learning, their interaction in the brain is not fully understood. Utilizing the spatial and temporal resolutions of fMRI and EEG, respectively, we examined a long-lag classification priming paradigm that required response repetitions or reversals at multiple levels of response representation. We found a repetition effect in occipital/temporal cortex (fMRI) that was time-locked to stimulus onset (EEG) and robust to switches in response, together with a repetition effect in inferior pFC (fMRI) that was time-locked to response onset (EEG) and sensitive to switches in response. The response-sensitive effect occurred even when changing from object names (words) to object pictures between repetitions, suggesting that S-R bindings can code abstract representations of stimuli. Most importantly, we found evidence for interference effects when incongruent S-R bindings were retrieved, with increased neural activity in inferior pFC, demonstrating that retrieval of S-R bindings can result in facilitation or interference, depending on the congruency of response between repetitions.
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Pundik, Svetlana, Adam D. Falchook, Jessica McCabe, Krisanne Litinas e Janis J. Daly. "Functional Brain Correlates of Upper Limb Spasticity and Its Mitigation following Rehabilitation in Chronic Stroke Survivors". Stroke Research and Treatment 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/306325.
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Background.Arm spasticity is a challenge in the care of chronic stroke survivors with motor deficits. In order to advance spasticity treatments, a better understanding of the mechanism of spasticity-related neuroplasticity is needed.Objective.To investigate brain function correlates of spasticity in chronic stroke and to identify specific regional functional brain changes related to rehabilitation-induced mitigation of spasticity.Methods.23 stroke survivors (>6 months) were treated with an arm motor learning and spasticity therapy (5 d/wk for 12 weeks). Outcome measures included Modified Ashworth scale, sensory tests, and functional magnetic resonance imaging (fMRI) for wrist and hand movement.Results.First, at baseline, greater spasticity correlated with poorer motor function (P=0.001) and greater sensory deficits (P=0.003). Second, rehabilitation produced improvement in upper limb spasticity and motor function (P<0.0001). Third, at baseline, greater spasticity correlated with higher fMRI activation in the ipsilesional thalamus (rho=0.49,P=0.03). Fourth, following rehabilitation, greater mitigation of spasticity correlated with enhanced fMRI activation in the contralesional primary motor (r=-0.755,P=0.003), premotor (r=−0.565,P=0.04), primary sensory (r=−0.614,P=0.03), and associative sensory (r=−0.597,P=0.03) regions while controlling for changes in motor function.Conclusions.Contralesional motor regions may contribute to restoring control of muscle tone in chronic stroke.
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Windischberger, C., C. Kasess, R. Sladky, E. Moser, S. Kasper e R. Lanzenberger. "FC07-06 - Differences in the modulatory role of escitalopram and citalopram revealed by effective connectivity analysis". European Psychiatry 26, S2 (março de 2011): 1851. http://dx.doi.org/10.1016/s0924-9338(11)73555-6.
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IntroductionCitalopram is a widely applied SSRI in patients suffering from affective disorder. It is a racemic mixture of the S- and R-enantiomer of citalopram, consisting of equal parts of S-citalopram and R-citalopram, respectively. It has been shown that the inhibitory potency in serotonin reuptake of S-citalopram is much higher compared to R-citalopram, and it is assumed that S-citalopram is the main carrier of the antidepressant effect.ObjectivesHere we investigated the effects of the two SSRIs Citalopram (50% S-, 50% R-citalopram) and Escitalopram (100% S-citalopram) on brain networks during emotion processing using pharmacological functional magnetic resonance imaging (fMRI) and dynamic causal modelling (DCM), an advanced tool to investigate functional integration between different brain regions.MethodsOur results are based on a placebo-controlled, randomized, double-blind, cross-over pharmacological study in 16 healthy subjects during three fMRI scanning sessions performing a facial emotional discrimination paradigm (Windischberger, Neuroimage, 2010). 32 models of pharmacological modulation within the amygdalar-parahippocampal-orbitofrontal network were analysed using Bayesian Model Averaging (BMA) as implemented in SPM8.ResultsS-citalopram showed statistically significant modulatory effects on forward amygdala-orbitofrontal and bidirectional amygdala-parahippocampal connections. No significant modulatory effects of R-citalopram were found.ConclusionsThis is the first fMRI study that showed stimulus-specific differential effects of the two enantiomeres R- and S-citalopram at the neural connectivity level. Our results corroborate studies in rats where escitalopram-induced increases in extracellular serotonin levels were found attenuated when R-citalopram was coinjected. Taken together this might explain the response differences between study drugs as demonstrated in previous clinical trials.
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Ramirez-Villegas, Juan F., Nikos K. Logothetis e Michel Besserve. "Diversity of sharp-wave–ripple LFP signatures reveals differentiated brain-wide dynamical events". Proceedings of the National Academy of Sciences 112, n.º 46 (4 de novembro de 2015): E6379—E6387. http://dx.doi.org/10.1073/pnas.1518257112.
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Sharp-wave–ripple (SPW-R) complexes are believed to mediate memory reactivation, transfer, and consolidation. However, their underlying neuronal dynamics at multiple scales remains poorly understood. Using concurrent hippocampal local field potential (LFP) recordings and functional MRI (fMRI), we study local changes in neuronal activity during SPW-R episodes and their brain-wide correlates. Analysis of the temporal alignment between SPW and ripple components reveals well-differentiated SPW-R subtypes in the CA1 LFP. SPW-R–triggered fMRI maps show that ripples aligned to the positive peak of their SPWs have enhanced neocortical metabolic up-regulation. In contrast, ripples occurring at the trough of their SPWs relate to weaker neocortical up-regulation and absent subcortical down-regulation, indicating differentiated involvement of neuromodulatory pathways in the ripple phenomenon mediated by long-range interactions. To our knowledge, this study provides the first evidence for the existence of SPW-R subtypes with differentiated CA1 activity and metabolic correlates in related brain areas, possibly serving different memory functions.
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Strandberg, Maria, Peter Mannfolk, Lars Stenberg, Hanna Ljung, Ia Rorsman, Elna-Marie Larsson, Danielle van Westen e Kristina Källén. "A Functional MRI-Based Model for Individual Memory Assessment in Patients Eligible for Anterior Temporal Lobe Resection". Open Neuroimaging Journal 11, n.º 1 (31 de março de 2017): 1–16. http://dx.doi.org/10.2174/1874440001711010001.
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Title:A functional (f) MRI-based model for individual memory assessment in patients eligible for temporal lobe resection.Aim:To investigate if pre-operative fMRI memory paradigms, add predictive information with regard to post-surgical memory deficits.Methods:Fourteen pharmacoresistant Temporal Lobe Epilepsy (TLE) patients accepted for Anterior Temporal Lobe Resection (ATLR) were included. A clinical risk assessment score (RAS 0-3) was constructed from structural MRI, neuropsychological testing and hemisphere dominance. fMRI lateralization indices (LIs) over frontal language and medial temporal regions were calculated. Predictive value from clinical risk scoring and added value from fMRI LIs were correlated to post-surgical memory change scores (significant decline -1 SD). Verbal memory outcome was classified either as expected (RAS 2-3 and post-operative decline; RAS 0-1 and intact post-operative verbal memory) or as unexpected (RAS 2-3 and intact post-operative verbal memory post-surgery; RAS 0-1 and post-operative decline).Results:RAS for verbal memory decline exhibited a specificity of 67% and a sensitivity of 75%. Significant correlations were found between frontal language LIs and post-operative verbal memory (r = -0.802; p = 0.017) for left (L) TLE and between medial temporal lobe LIs and visuospatial memory (r = 0.829; p = 0.021), as well as verbal memory (r = 0.714; p = 0.055) for right (R) TLE. Ten patients had expected outcome and four patients had an unexpected outcome. In two MRI-negative RTLE patients that suffered significant verbal memory decline post-operatively, fMRI identified bilateral language and right lateralized medial temporal verbal encoding. In two LTLE patients with MRI pathology and verbal memory dysfunction, neither RAS nor fMRI identified the risk for aggravated verbal memory decline following ATLR.Conclusion:fMRI visualization of temporal-frontal network activation may add value to the pre-surgical work-up in epilepsy patients eligible for ATLR. Frontal language patterns are important for prediction in both L and RTLE. Strong left lateralized language in LTLE, as well as bilateral language combined with right lateralized encoding in RTLE, seems to indicate an increased risk for post-operative verbal memory decline.
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Gupta, Daya. "Autism Detection using r-fMRI: Subspace Approximation and CNN Based Approach". International Journal of Advanced Trends in Computer Science and Engineering 9, n.º 2 (2020): 1029–36. http://dx.doi.org/10.30534/ijatcse/2020/20912020.
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Gupta, Daya. "Autism Detection using r-fMRI: Subspace Approximation and CNN Based Approach". International Journal of Advanced Trends in Computer Science and Engineering 9, n.º 2 (25 de abril de 2020): 1029–36. http://dx.doi.org/10.30534/ijatcse/2020/20922020.
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JOHNSON, STERLING C., ANDREW J. SAYKIN, LAURA A. FLASHMAN, THOMAS W. McALLISTER e MOLLY B. SPARLING. "Brain activation on fMRI and verbal memory ability: Functional neuroanatomic correlates of CVLT performance". Journal of the International Neuropsychological Society 7, n.º 1 (janeiro de 2001): 55–62. http://dx.doi.org/10.1017/s135561770171106x.
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We have recently reported (Saykin et al., 1999b) selective activation of left medial temporal lobe structures during processing of novel compared to familiar words using functional magnetic resonance imaging (fMRI). The current study describes the relationship between a widely used clinical test of verbal learning, the California Verbal Learning Test (CVLT), and the previously reported fMRI activations. Thirteen right-handed healthy adult participants were studied with whole brain echo-planar fMRI while listening to novel and recently learned (familiar) words intermixed pseudorandomly in an event-related design. These participants were also tested with the CVLT. Scores for CVLT Trial 1 (immediate encoding of novel words) and recognition discriminability (recognition of familiar vs. novel words) were correlated with fMRI signal change during processing of novel versus familiar words using a covariance model implemented in SPM96. For the novel words analysis, voxels in the right anterior hippocampus correlated significantly with Trial 1 (r = .76 at the maxima). For the recognition analysis, a significant cluster of voxels was found in the right dorsolateral prefrontal cortex (r = .88 at the maxima). Our prior results of separable left medial temporal activation to novel and familiar words, together with results of the covariance analyses reported here, suggest that in addition to the left medial temporal lobe (MTL) regions that are engaged during novel and familiar word processing, the right hippocampus and right frontal lobe are also involved, particularly in those participants with better memory ability. This positive relationship between fMRI activation and CVLT performance suggests a role for these right hemisphere regions in successful memory processing of verbal material, perhaps reflecting more efficient encoding and retrieval strategies that facilitate memory. (JINS, 2001, 7, 55–62.)
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Xia, Wenqing, Yu-Chen Chen, Yong Luo, Dan-Feng Zhang, Huiyou Chen, Jianhua Ma e Xindao Yin. "Decreased Spontaneous Brain Activity and Functional Connectivity in Type 1 Diabetic Patients Without Microvascular Complications". Cellular Physiology and Biochemistry 51, n.º 6 (2018): 2694–703. http://dx.doi.org/10.1159/000495960.
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Background/Aims: Type 1 diabetes mellitus (T1DM) has been proven to be associated with an increased risk of cognitive dysfunction. In this study, we aimed to investigate whether disrupted spontaneous activity and functional connectivity (FC) exist in T1DM patients using resting-state functional magnetic resonance imaging (rs-fMRI) and to detect the relationships of these parameters with cognitive impairment. Methods: T1DM patients (n=35) were compared with age-, sex-, and education level-matched healthy controls (n=50) through rs-fMRI. Using rs-fMRI professional software, we calculated the amplitude of low-frequency fluctuation (ALFF), regional homogeneity (ReHo), and seed-based FC in the posterior cingulate cortex (PCC) to measure the spontaneous neural activity in the groups. The relationship between rs-fMRI data and cognitive performance was further investigated. Results: Compared with the healthy controls, T1DM patients showed significantly decreased ALFF values in the PCC and right inferior frontal gyrus (IFG), decreased ReHo values in the right middle frontal gyrus (MFG) and reduced FC between the PCC and the right MFG. Furthermore, a positive correlation was found between decreased ALFF values in the PCC and Rey-Osterrieth Complex Figure Test (CFT)-delay scores in T1DM patients (r=0.394, p=0.026). Moreover, the Trail Making Test-B (TMT-B) scores showed negative correlations with decreased ReHo values in the right MFG (r=-0.468, p=0.007) and reduced FC between the PCC and right MFG (r=-0.425, p=0.015). Conclusion: Our combined analyses revealed decreased spontaneous activity and FC mainly within the default mode network, which was correlated with specific impaired cognitive functioning in T1DM. This study thus elucidates the neurophysiological mechanisms underlying T1DM-related cognitive impairment and may serve as a reference for future clinical diagnosis.
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Macey, Paul M., Philip J. Schluter, Katherine E. Macey e Ronald M. Harper. "Detecting variable responses in time-series using repeated measures ANOVA: Application to physiologic challenges". F1000Research 5 (8 de julho de 2016): 563. http://dx.doi.org/10.12688/f1000research.8252.2.
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We present an approach to analyzing physiologic timetrends recorded during a stimulus by comparing means at each time point using repeated measures analysis of variance (RMANOVA). The approach allows temporal patterns to be examined without an a priori model of expected timing or pattern of response. The approach was originally applied to signals recorded from functional magnetic resonance imaging (fMRI) volumes-of-interest (VOI) during a physiologic challenge, but we have used the same technique to analyze continuous recordings of other physiological signals such as heart rate, breathing rate, and pulse oximetry. For fMRI, the method serves as a complement to whole-brain voxel-based analyses, and is useful for detecting complex responses within pre-determined brain regions, or as a post-hoc analysis of regions of interest identified by whole-brain assessments. We illustrate an implementation of the technique in the statistical software packages R and SAS. VOI timetrends are extracted from conventionally preprocessed fMRI images. A timetrend of average signal intensity across the VOI during the scanning period is calculated for each subject. The values are scaled relative to baseline periods, and time points are binned. In SAS, the procedure PROC MIXED implements the RMANOVA in a single step. In R, we present one option for implementing RMANOVA with the mixed model function “lme”. Model diagnostics, and predicted means and differences are best performed with additional libraries and commands in R; we present one example. The ensuing results allow determination of significant overall effects, and time-point specific within- and between-group responses relative to baseline. We illustrate the technique using fMRI data from two groups of subjects who underwent a respiratory challenge. RMANOVA allows insight into the timing of responses and response differences between groups, and so is suited to physiologic testing paradigms eliciting complex response patterns.
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Silva, Guilherme, e Alberto Citterio. "Hemispheric asymmetries in dorsal language pathway white-matter tracts: A magnetic resonance imaging tractography and functional magnetic resonance imaging study". Neuroradiology Journal 30, n.º 5 (12 de julho de 2017): 470–76. http://dx.doi.org/10.1177/1971400917720829.
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Introduction Previous studies have shown that the arcuate fasciculus has a leftward asymmetry in right-handers that could be correlated with the language lateralisation defined by functional magnetic resonance imaging. Nonetheless, information about the asymmetry of the other fibres that constitute the dorsal language pathway is scarce. Objectives This study investigated the asymmetry of the white-matter tracts involved in the dorsal language pathway through the diffusion tensor imaging (DTI) technique, in relation to language hemispheric dominance determined by task-dependent functional magnetic resonance imaging (fMRI). Methods We selected 11 patients (10 right-handed) who had been studied with task-dependent fMRI for language areas and DTI and who had no language impairment or structural abnormalities that could compromise magnetic resonance tractography of the fibres involved in the dorsal language pathway. Laterality indices (LI) for fMRI and for the volumes of each tract were calculated. Results In fMRI, all the right-handers had left hemispheric lateralisation, and the ambidextrous subject presented right hemispheric dominance. The arcuate fasciculus LI was strongly correlated with fMRI LI ( r = 0.739, p = 0.009), presenting the same lateralisation of fMRI in seven subjects (including the right hemispheric dominant). It was not asymmetric in three cases and had opposite lateralisation in one case. The other tracts presented predominance for rightward lateralisation, especially superior longitudinal fasciculus (SLF) II/III (nine subjects), but their LI did not correlate (directly or inversely) with fMRI LI. Conclusion The fibres that constitute the dorsal language pathway have an asymmetric distribution in the cerebral hemispheres. Only the asymmetry of the arcuate fasciculus is correlated with fMRI language lateralisation.
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Sumiyoshi, C., K. Matsuo, C. Kato, F. Ozawa, Y. Takehara, H. Isoda, S. Isogai, T. Moriya, H. Sakahara e T. Nakai. "Brain activities in memory process for “I” and “r”: An fMRI study". NeuroImage 13, n.º 6 (junho de 2001): 610. http://dx.doi.org/10.1016/s1053-8119(01)91953-6.
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Sartipi, Shadi, Hashem Kalbkhani e Mahrokh G. Shayesteh. "Diagnosis of schizophrenia from R-fMRI data using Ripplet transform and OLPP". Multimedia Tools and Applications 79, n.º 31-32 (9 de junho de 2020): 23401–23. http://dx.doi.org/10.1007/s11042-020-09122-y.
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Deppe, Michael, Stefan Knecht, Karsten Papke, Hubertus Lohmann, Helge Fleischer, Walter Heindel, E. Bernd Ringelstein e Henning Henningsen. "Assessment of Hemispheric Language Lateralization: A Comparison between fMRI and fTCD". Journal of Cerebral Blood Flow & Metabolism 20, n.º 2 (fevereiro de 2000): 263–68. http://dx.doi.org/10.1097/00004647-200002000-00006.
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The cerebral blood flow velocity (CBFV) in the basal arteries during a word-generation task was assessed by functional transcranial Doppler ultrasonography (fTCD) and by functional magnetic resonance imaging (fMRI). The study investigates how event-related CBFV modulations in the middle cerebral artery (MCA) relate to regional cerebral blood flow (rCBF) changes. Both fMRI and fTCD were used in 13 subjects (7 men, 6 women, aged 21 to 44 years). The maximum difference of relative CBFV changes between the left and right MCA during the word-generation task was used as the language laterality index ( LIfTCD). For the fMRI examination during the nearly identical language task, the corresponding index was defined by LIfMRI = 100(NL − NR)/(NL + NR), where NL and NR refer to the numbers of voxels activated in the left and right hemisphere, respectively. The evoked CBFV changes expressed by LIfTCD and the corresponding laterality index, LIfMRI, estimated by fMRI showed a close linear relation (regression analysis: r = 0.95, p < 0.0001). The results of this study demonstrate that language-related velocity changes in the MCAs relate to rCBF increases in a linear fashion. Since the laterality indices assessed by fMRI and fTCD are in such close agreement both techniques can therefore be used in a complementary way.
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Arun, KM, KA Smitha, PG Rajesh e Chandrasekharan Kesavadas. "Functional near-infrared spectroscopy is in moderate accordance with functional MRI in determining lateralisation of frontal language areas". Neuroradiology Journal 31, n.º 2 (26 de outubro de 2017): 133–41. http://dx.doi.org/10.1177/1971400917739083.
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Purpose Understanding language dominance is crucial in pre-surgical evaluation of patients with epilepsy and in patients having a tumour close to the language area. Functional magnetic resonance imaging (fMRI) studies are well established in evaluating language dominance. Functional near-infrared spectroscopy (fNIRS) is a non-invasive optical imaging modality that offers a convenient and affordable technique to image language-related cortical areas. This study investigates the agreement between results from task-based fMRI and fNIRS in determining language lateralisation. Methods Language laterality indices LIs were calculated from both fMRI and fNIRS measurements of the same individual volunteers by using an identical paradigm. Statistical measures of percentage agreement and kappa value have been calculated for testing agreement and reliability. Results A correlation analysis of the LI values shows a good correlation with r = 0.677 at p < 0.05. Statistical comparison of both fMRI and fNIRS methods for language lateralisation yielded a percentage agreement of 90% and a moderate kappa value of κ = 0.621. Conclusion Our study suggests that fNIRS is in moderate accordance with fMRI in determining lateralisation of the frontal language areas. It implies that the optical imaging technique can provide additional information on functional lateralisation of frontal language areas.
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Shih, Yen-Yu Ian, Shiliang Huang, You-Yin Chen, Hsin-Yi Lai, Yu-Chieh Jill Kao, Fang Du, Edward S. Hui e Timothy Q. Duong. "Imaging Neurovascular Function and Functional Recovery after Stroke in the Rat Striatum Using Forepaw Stimulation". Journal of Cerebral Blood Flow & Metabolism 34, n.º 9 (11 de junho de 2014): 1483–92. http://dx.doi.org/10.1038/jcbfm.2014.103.
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Negative functional magnetic resonance imaging (fMRI) response in the striatum has been observed in several studies during peripheral sensory stimulation, but its relationship between local field potential (LFP) remains to be elucidated. We performed cerebral blood volume (CBV) fMRI and LFP recordings in normal rats during graded noxious forepaw stimulation at nine stimulus pulse widths. Albeit high LFP-CBV correlation was found in the ipsilateral and contralateral sensory cortices (r = 0.89 and 0.95, respectively), the striatal CBV responses were neither positively, nor negatively correlated with LFP (r = 0.04), demonstrating that the negative striatal CBV response is not originated from net regional inhibition. To further identify whether this negative CBV response can serve as a marker for striatal functional recovery, two groups of rats ( n = 5 each) underwent 20- and 45-minute middle cerebral artery occlusion (MCAO) were studied. No CBV response was found in the ipsilateral striatum in both groups immediately after stroke. Improved striatal CBV response was observed on day 28 in the 20-minute MCAO group compared with the 45-minute MCAO group ( P<0.05). This study shows that fMRI signals could differ significantly from LFP and that the observed negative CBV response has potential to serve as a marker for striatal functional integrity in rats.
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Okuneye, Victoria, Brett Clementz, Elliot Gershon, Matcheri Keshavan, Jennifer E. McDowell, Godfrey Pearlson, Carol Tamminga, John Sweeney e Sarah Keedy. "O2.6. DELUSIONS ASSOCIATED WITH ABNORMAL FRONTOSTRIATAL EFFECTIVE CONNECTIVITY IN A SPECTRAL DCM ANALYSIS OF RESTING STATE FMRI". Schizophrenia Bulletin 46, Supplement_1 (abril de 2020): S5. http://dx.doi.org/10.1093/schbul/sbaa028.011.
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Abstract Background Delusions, false beliefs held in the face of disconfirming evidence, are a prevalent and highly distressing feature of psychotic disorders. The neurobiology of delusions remains unknown but recent evidence suggests a role for abnormal prediction error neural signaling. Prediction error is neurocognitive process in which the brain signals the need to update beliefs when presented with information that disconfirms expectations. Task based neuroimaging studies have identified delusional beliefs correlate with altered activation in frontal and subcortical brain regions during prediction error, though such work is limited in scope. In a large sample of transdiagnostic psychotic patients we modeled the resting state effective connectivity of the delusion-associated predication error (D-PE) circuit. Methods Resting state fMRI was obtained from 289 psychotic subjects (schizophrenia, schizoaffective disorder, bipolar disorder with psychotic features) and 219 healthy controls, recruited as part of the multisite Bipolar & Schizophrenia Network on Intermediate Phenotypes (BSNIP1) study. Neuroimaging data were processed using CONN software with strict quality control criteria. Five D-PE regions of interest (ROIs) were created based on peak coordinates from published task-based prediction error fMRI studies: right Dorsolateral Prefrontal Cortex [r DLPFC], r Ventrolateral Prefrontal Cortex [r VLPFC], r Caudate, l Caudate and l Midbrain. In each subject the first eigenvariate was extracted from the rs-fMRI timeseries of each D-PE ROI. Spectral Dynamic Causal Modeling (spDCM) was performed on a fully connected model of the 5 ROIs. Parameters for the full model were fit using Parameter Empirical Bayes (PEB) and then passed to the group level where they were reduced using Bayesian Model Averaging (BMA). The association of effective connectivity with current delusional severity was tested using PEB-BMA controlling for antipsychotic medication, sex, age and scanner site. Significant effective connectivity was identified as parameters with free energy evidence greater than 95% probability. Additionally, we assessed the effective connectivity differences of this circuit between psychotic probands and healthy controls. Results Greater delusional severity was significantly associated with inhibition of the r Caudate by the r VLPFC, excitation of the r DLPFC by the l Caudate, and decreased self-inhibition of the r VLPFC and r DLPFC. Effective connectivity of the D-PE network in psychotic probands compared to healthy controls was associated with inhibition of the r Caudate by the r VLPFC, the r DLPFC by the l Midbrain, the l Midbrain by the r Caudate, and decreased self-inhibition of the r Caudate, r VLPFC, and r DLPFC. Discussion We found that resting state effective connectivity of the prediction error circuit is disrupted in psychotic subjects experiencing delusions. Specifically, delusion severity was associated with both increased bottom-up and decreased top-down frontostriatal connectivity along with greater disinhibition of the r VLPFC and r DLPFC. These effective connectivity results provide novel insight into the causal paths which may underlie delusion neural circuitry. This provides further evidence that dysconnectivity of prediction error system is a biomarker of delusions in psychosis. Furthermore, these transdiagnostic results implicate frontostriatal dysconnectivity as common neuropathology in delusions.
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Forman, Steven D., Afonso C. Silva, Nikolas Dedousis, Emmanuel L. Barbier, John D. Fernstrom e Alan P. Koretsky. "Simultaneous Glutamate and Perfusion fMRI Responses to Regional Brain Stimulation". Journal of Cerebral Blood Flow & Metabolism 18, n.º 10 (outubro de 1998): 1064–70. http://dx.doi.org/10.1097/00004647-199810000-00002.
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Functional magnetic resonance imaging (fMRI) rests on the assumption that regional brain activity is closely coupled to regional cerebral blood flow (rCBF) in vivo. To test the degree of coupling, cortical brain activity was locally stimulated in rats by reversed microdialysis infusion of picrotoxinin, a γ-aminobutyric acid-A antagonist. Before and during the first 30 minutes of infusion, simultaneous fMRI (rCBF) and neurochemical (interstitial glutamate concentration) measures of brain activity were highly correlated (r = 0.83). After 30 minutes of picrotoxinin-induced stimulation, glutamate levels decreased but rCBF remained elevated, suggesting that additional factors modulate the relationship between neuronal neurotransmitters and hemodynamics at these later stages.
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Anderson, John R., e Yulin Qin. "Using Brain Imaging to Extract the Structure of Complex Events at the Rational Time Band". Journal of Cognitive Neuroscience 20, n.º 9 (setembro de 2008): 1624–36. http://dx.doi.org/10.1162/jocn.2008.20108.
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A functional magnetic resonance imaging (fMRI) study was performed in which participants performed a complex series of mental calculations that spanned about 2 min. An Adaptive Control of Thought—Rational (ACT-R) model [Anderson, J. R. How can the human mind occur in the physical universe? New York: Oxford University Press, 2007] was developed that successfully fit the distribution of latencies. This model generated predictions for the fMRI signal in six brain regions that have been associated with modules in the ACT-R theory. The model's predictions were confirmed for a fusiform region that reflects the visual module, for a prefrontal region that reflects the retrieval module, and for an anterior cingulate region that reflects the goal module. In addition, the only significant deviations to the motor region that reflects the manual module were anticipatory hand movements. In contrast, the predictions were relatively poor for a parietal region that reflects an imaginal module and for a caudate region that reflects the procedural module. Possible explanations of these poor fits are discussed. In addition, exploratory analyses were performed to find regions that might correspond to the predictions of the modules.
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Xie, Hua, Iliana I. Karipidis, Amber Howell, Meredith Schreier, Kristen E. Sheau, Mai K. Manchanda, Rafi Ayub et al. "Finding the neural correlates of collaboration using a three-person fMRI hyperscanning paradigm". Proceedings of the National Academy of Sciences 117, n.º 37 (25 de agosto de 2020): 23066–72. http://dx.doi.org/10.1073/pnas.1917407117.
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Humans have an extraordinary ability to interact and cooperate with others. Despite the social and evolutionary significance of collaboration, research on finding its neural correlates has been limited partly due to restrictions on the simultaneous neuroimaging of more than one participant (also known as hyperscanning). Several studies have used dyadic fMRI hyperscanning to examine the interaction between two participants. However, to our knowledge, no study to date has aimed at revealing the neural correlates of social interactions using a three-person (or triadic) fMRI hyperscanning paradigm. Here, we simultaneously measured the blood-oxygenation level-dependent signal from 12 triads (n = 36 participants), while they engaged in a collaborative drawing task based on the social game of Pictionary. General linear model analysis revealed increased activation in the brain regions previously linked with the theory of mind during the collaborative phase compared to the independent phase of the task. Furthermore, using intersubject correlation analysis, we revealed increased synchronization of the right temporo‐parietal junction (R TPJ) during the collaborative phase. The increased synchrony in the R TPJ was observed to be positively associated with the overall team performance on the task. In sum, our paradigm revealed a vital role of the R TPJ among other theory-of-mind regions during a triadic collaborative drawing task.
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Eloyan, Ani, Shanshan Li, John Muschelli, Jim J. Pekar, Stewart H. Mostofsky e Brian S. Caffo. "Analytic Programming with fMRI Data: A Quick-Start Guide for Statisticians Using R". PLoS ONE 9, n.º 2 (28 de fevereiro de 2014): e89470. http://dx.doi.org/10.1371/journal.pone.0089470.
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He, Fangmei, Youjun Li, Chenxi Li, Liming Fan, Tian Liu e Jue Wang. "Repeated anodal high-definition transcranial direct current stimulation over the left dorsolateral prefrontal cortex in mild cognitive impairment patients increased regional homogeneity in multiple brain regions". PLOS ONE 16, n.º 8 (13 de agosto de 2021): e0256100. http://dx.doi.org/10.1371/journal.pone.0256100.
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Transcranial direct current stimulation (tDCS) can improve cognitive function. However, it is not clear how high-definition tDCS (HD-tDCS) regulates the cognitive function and its neural mechanism, especially in individuals with mild cognitive impairment (MCI). This study aimed to examine whether HD-tDCS can modulate cognitive function in individuals with MCI and to determine whether the potential variety is related to spontaneous brain activity changes recorded by resting-state functional magnetic resonance imaging (rs-fMRI). Forty-three individuals with MCI were randomly assigned to receive either 10 HD-tDCS sessions or 10 sham sessions to the left dorsolateral prefrontal cortex (L-DLPFC). The fractional amplitude of low-frequency fluctuation (fALFF) and the regional homogeneity (ReHo) was computed using rs-fMRI data from all participants. The results showed that the fALFF and ReHo values changed in multiple areas following HD-tDCS. Brain regions with significant decreases in fALFF values include the Insula R, Precuneus R, Thalamus L, and Parietal Sup R, while the Temporal Inf R, Fusiform L, Occipital Sup L, Calcarine R, and Angular R showed significantly increased in their fALFF values. The brain regions with significant increases in ReHo values include the Temporal Inf R, Putamen L, Frontal Mid L, Precentral R, Frontal Sup Medial L, Frontal Sup R, and Precentral L. We found that HD-tDCS can alter the intensity and synchrony of brain activity, and our results indicate that fALFF and ReHo analysis are sensitive indicators for the detection of HD-tDCS during spontaneous brain activity. Interestingly, HD-tDCS increases the ReHo values of multiple brain regions, which may be related to the underlying mechanism of its clinical effects, these may also be related to a potential compensation mechanism involving the mobilization of more regions to complete a function following a functional decline.
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Presciutti, O., G. P. Pelliccioli, R. Tarducci, P. Chiarini e G. Gobbi. "New Processing Methods in Functional MRI". Rivista di Neuroradiologia 10, n.º 3 (junho de 1997): 261–64. http://dx.doi.org/10.1177/197140099701000301.
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Two processing methods of fMRI data are proposed: vector orthogonalization and Fisher transformation of correlation coefficients (cc) distribution. The former is based on orthogonalization of vectors V (time course of signal intensity) and R (noise) to make V independent from R. The latter is based on Fisher transformation of cc distribution. From this distribution, by usual statistical tests, it is possible to detect the values of the cc that are significantly different from the mean in order to select activated pixels.
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Tong, Jiajie, Chunhui Shan e Congcong Hu. "The Value of Brain Resting-State Functional Magnetic Resonance Imaging on Image Registration Algorithm in Analyzing Abnormal Changes of Neuronal Activity in Patients with Type 2 Diabetes". Contrast Media & Molecular Imaging 2021 (13 de agosto de 2021): 1–9. http://dx.doi.org/10.1155/2021/6951755.
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The aim of this paper was to analyze the application value of resting-state functional magnetic resonance imaging (FMRI) parameters and rigid transformation algorithm in patients with type 2 diabetes (T2DM), which could provide a theoretical basis for the registration application of FMRI. 107 patients confirmed pathologically as T2DM and 51 community medical healthy volunteers were selected and divided into an experimental group and a control group, respectively. Besides, all the subjects were scanned with FMRI. Then, the rigid transformation-principal axis algorithm (RT-PAA), Levenberg–Marquardt iterative closest point (LMICP), and Demons algorithm were applied to magnetic resonance image registration. It was found that RT-PAA was superior to LMICP and Demons in image registration. The amplitude of low-frequency fluctuation (ALFF) values of the left middle temporal gyrus, right middle temporal gyrus, left fusiform gyrus, right inferior occipital gyrus, and left middle occipital gyrus in patients from the experimental group were lower than those of the control group P < 0.05 . The Montreal cognitive assessment (MoCA) score was extremely negatively correlated with the ALFF of the left middle temporal gyrus (r = −0.451 and P < 0.001 ) and highly positively associated with the ALFF of the right posterior cerebellar lobe (r = −0.484 and P < 0.001 ). In addition, the MoCA score of patients had a dramatically negative correlation with the ALFF of the left middle temporal gyrus (r = −0.602 and P < 0.001 ) and had a greatly positive correlation with the ALFF of the right posterior cerebellar lobe (r = −0.516 and P < 0.001 ). The results showed that RT-PAA based on rigid transformation in this study had a good registration effect on magnetic resonance images. Compared with healthy volunteers, the left middle temporal gyrus, right middle temporal gyrus, left fusiform gyrus, right inferior occipital gyrus, and left middle occipital gyrus in patients with T2DM showed abnormal neuronal changes and reduced cognitive function.
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Yoshino, A., Y. Okamoto, G. Okada, M. Takamura, N. Ichikawa, C. Shibasaki, S. Yokoyama et al. "Changes in resting-state brain networks after cognitive–behavioral therapy for chronic pain". Psychological Medicine 48, n.º 7 (12 de setembro de 2017): 1148–56. http://dx.doi.org/10.1017/s0033291717002598.
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AbstractBackgroundCognitive–behavioral therapy (CBT) is thought to be useful for chronic pain, with the pathology of the latter being closely associated with cognitive–emotional components. However, there are few resting-state functional magnetic resonance imaging (R-fMRI) studies. We used the independent component analysis method to examine neural changes after CBT and to assess whether brain regions predict treatment response.MethodsWe performed R-fMRI on a group of 29 chronic pain (somatoform pain disorder) patients and 30 age-matched healthy controls (T1). Patients were enrolled in a weekly 12-session group CBT (T2). We assessed selected regions of interest that exhibited differences in intrinsic connectivity network (ICN) connectivity strength between the patients and controls at T1, and compared T1 and T2. We also examined the correlations between treatment effects and rs-fMRI data.ResultsAbnormal ICN connectivity of the orbitofrontal cortex (OFC) and inferior parietal lobule within the dorsal attention network (DAN) and of the paracentral lobule within the sensorimotor network in patients with chronic pain normalized after CBT. Higher ICN connectivity strength in the OFC indicated greater improvements in pain intensity. Furthermore, ICN connectivity strength in the dorsal posterior cingulate cortex (PCC) within the DAN at T1 was negatively correlated with CBT-related clinical improvements.ConclusionsWe conclude that the OFC is crucial for CBT-related improvement of pain intensity, and that the dorsal PCC activation at pretreatment also plays an important role in improvement of clinical symptoms via CBT.
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Liu, Tao, Jianjun Li, Zhiqiang Zhang, Qiang Xu, Guangming Lu, Shixiong Huang, Mengjie Pan e Feng Chen. "Altered Long- and Short-Range Functional Connectivity in Patients with Betel Quid Dependence: A Resting-State Functional MRI Study". Cellular Physiology and Biochemistry 40, n.º 6 (2016): 1626–36. http://dx.doi.org/10.1159/000453212.
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Objective: Addiction is a chronic relapsing brain disease. Brain structural abnormalities may constitute an abnormal neural network that underlies the risk of drug dependence. We hypothesized that individuals with Betel Quid Dependence (BQD) have functional connectivity alterations that can be described by long- and short-range functional connectivity density(FCD) maps. Methods: We tested this hypothesis using functional magnetic resonance imaging (fMRI) data from subjects of the Han ethnic group in Hainan, China. Here, we examined BQD individuals (n = 33) and age-, sex-, and education-matched healthy controls (HCs) (n = 32) in a rs-fMRI study to observe FCD alterations associated with the severity of BQD. Results: Compared with HCs, long-range FCD was decreased in the right anterior cingulate cortex (ACC) and increased in the left cerebellum posterior lobe (CPL) and bilateral inferior parietal lobule (IPL) in the BQD group. Short-range FCD was reduced in the right ACC and left dorsolateral prefrontal cortex (dlPFC), and increased in the left CPL. The short-range FCD alteration in the right ACC displayed a negative correlation with the Betel Quid Dependence Scale (BQDS) (r=-0.432, P=0.012), and the long-range FCD alteration of left IPL showed a positive correlation with the duration of BQD(r=0.519, P=0.002) in BQD individuals. Conclusions: fMRI revealed differences in long- and short- range FCD in BQD individuals, and these alterations might be due to BQ chewing, BQ dependency, or risk factors for developing BQD.
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Nielsen, Mette, Egill Rostrup e Birte Glenthøj. "M148. NORMALIZATION IN REWARD PROCESSING DURING INITIAL TREATMENT MAY PREDICT LONG-TERM CLINICAL OUTCOME IN ANTIPSYCHOTIC NAïVE SCHIZOPHRENIA PATIENTS". Schizophrenia Bulletin 46, Supplement_1 (abril de 2020): S191—S192. http://dx.doi.org/10.1093/schbul/sbaa030.460.
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Abstract Background Decreased functional magnetic resonance (fMRI) signaling in ventral striatum during reward anticipation has been a consistent finding in unmedicated patients with schizophrenia. Antipsychotic medication may normalize this, which has been associated with improvement in psychotic symptoms. Whether this initial treatment response predict long term clinical outcome have not been examined previously. We here present unique data from a cohort of antipsychotic näive patients, who was examined before and after six weeks of antipsychotic monotherapy, and again after six years of naturalistic treatment. We hypothesized that improved reward related fMRI-signaling in striatum during initial treatment will be associated with less severe symptoms and a higher level of function after six years. Methods Antipsychotic-naïve, first episode patients with schizophrenia and matched healthy controls were examined at three timepoints: Baseline, after six weeks and after six years. During the first six weeks, patients were treated with a D2/3 antagonist, after which they switched to a naturalistic clinical setting. At all three timepoints, fMRI was obtained while participants played a monetary rewarding game. Mean contrast signal during anticipation of salient events was extracted from predefined regions of interest in nucleus accumbens and caudatus. Additionally, symptom severity and level of function were assessed in patients. Remission after six years was defined by the Andreasen criteria. Long term changes in patients were analyzed with paired t-test. Repeated measures ANOVA was used to compare fMRI signal in patients and controls over time. Changes in fMRI signal during the first six weeks was compared between remitted and unremitted patients with students t-test. Correlations between symptom severity, level of function and fMRI signal up were analyzed with Spearman or Pearson as appropriate. Results Long term follow-up data on fMRI and psychopathology was obtained from 25 patients and 28 controls 6.7 (4.3–8.7) years after baseline examinations. In patients, symptomatology and level of function was improved (all p<0.001), and remission criteria was met by 12 (48%) of the patients. Repeated measures ANOVA of the extracted fMRI contrast signal at baseline and six years showed a group*time interaction in left Nucleus accumbens (F=4.8, p= 0.038) and left caudatus (F= 4.08, p=0=049). Mean contrast signal increased in patients but decreased in healthy controls. Change in contrast signal in left caudatus during the first six weeks of treatment differed between remitted and non-remitted patients (t=2.2, p=0.044). An increase in signal during initial treatment was found in patients later being in remission, which was not observed in non-remitted patients. Decreased fMRI contrast signal in left caudatus at six years follow up was associated with a higher level of negative symptoms (r=-0.44, p=0.02) and a lower level of function (r=0.45, p=0.02). Discussion In this long-term follow up study, half of the patients were in remission 4–8 years after their first schizophrenia diagnosis. These individuals were characterized by a normalization of reward anticipation signaling in left striatal regions during their initial treatment with a selective D2/3 antagonist. Schizophrenia is a diagnosis with a heterogeneous outcome, and prognostic biomarkers are still missing. The present results suggest that normalization in reward processing during initial antipsychotic treatment may predict remission six years later. Although these results need to be reproduced, they do support the notion, that patients responding to antipsychotic treatment are characterized by changes in striatal function, which may be predictive for long-term outcome.
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Fan, Zhen, Xiao Chen, Zeng-Xin Qi, Le Li, Bin Lu, Cong-Lin Jiang, Ren-Qing Zhu, Chao-Gan Yan e Liang Chen. "Physiological significance of R-fMRI indices: Can functional metrics differentiate structural lesions (brain tumors)?" NeuroImage: Clinical 22 (2019): 101741. http://dx.doi.org/10.1016/j.nicl.2019.101741.
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Kulkarni, Prachi H., S. N. Merchant e Suyash Awate. "Dictionary+Wavelet Model With Nested-Minorized VB-EM for SMS-CAIPI R-fMRI Reconstruction". IEEE Open Journal of Signal Processing 2 (2021): 383–95. http://dx.doi.org/10.1109/ojsp.2021.3100751.
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Takahashi, H., N. Yahata, M. Matsuura, K. Asai, Y. Okubo, H. Tanaka e M. Koeda. "Neural Responses to Human Voice and Hemisphere Dominance for Lexical-semantic Processing". Methods of Information in Medicine 46, n.º 02 (2007): 247–50. http://dx.doi.org/10.1055/s-0038-1625416.
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Summary Objectives : In our previous functional magnetic resonance imaging (fMRI) study, we determined that there was distinct left hemispheric dominance for lexical- semantic processing without the influence of human voice perception in right-handed healthy subjects. However, the degree of right-handedness in the right-handed subjects ranged from 52 to 100 according to the Edinburgh Handedness Inventory (EHI) score. In the present study, we aimed to clarify the correlation between the degree of right-handedness and language dominance in the fronto-temporo-parietal cortices by examining cerebral activation for lexical-semantic processing. Methods : Twenty-seven normal right-handed healthy subjects were scanned by fMRI while listening to sentences (SEN), reverse sentences (rSEN), and identifiable non-vocal sounds (SND). Fronto-temporo-parietal activation was observed in the left hemisphere under the SEN - rSEN contrast, which included lexical- semantic processing without the influence of human voice perception. Laterality Indexwas calculated as LI = (L - R)/(L + R) X 100, L: left, R: right. Results : Laterality Index in the fronto-temporo-parietal cortices did not correlate with the degree of right-handedness in EHI score. Conclusions : The present study indicated that the degree of right-handedness from 52 to 100 in EHI score had no effect on the degree of left hemispheric dominance for lexical-semantic processing in right-handed healthy subjects.
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Kaur, Ardaman, Rishu Chaujar e Vijayakumar Chinnadurai. "Effects of Neural Mechanisms of Pretask Resting EEG Alpha Information on Situational Awareness: A Functional Connectivity Approach". Human Factors: The Journal of the Human Factors and Ergonomics Society 62, n.º 7 (28 de agosto de 2019): 1150–70. http://dx.doi.org/10.1177/0018720819869129.
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Objective In this study, the influence of pretask resting neural mechanisms on situational awareness (SA)-task is studied. Background Pretask electroencephalography (EEG) information and Stroop effect are known to influence task engagement independently. However, neural mechanisms of pretask resting absolute alpha (PRAA) and pretask resting alpha frontal asymmetry (PRAFA) in influencing SA-task which is undergoing Stroop effect is still not understood. Method The study involved pretask resting EEG measurements from 18 healthy individuals followed by functional magnetic resonance imaging (fMRI) acquisition during SA-task. To understand the effect of pretask alpha information and Stroop effect on SA, a robust correlation between mean reaction time, SA Index, PRAA, and PRAFA were assessed. Furthermore, neural underpinnings of PRAA, PRAFA in SA-task, and functional connectivity were analyzed through the EEG-informed fMRI approach. Results Significant robust correlation of reaction time was observed with SA Index (Pearson: r = .50, pcorr = .05) and PRAFA (Pearson: r = .63; pcorr = .01), respectively. Similarly, SA Index significantly correlated with PRAFA (Pearson: r = .56, pcorr = .01; Spearman: r = .61, pcorr = .007), and PRAA (Pearson: r = .59, pcorr = .005; Spearman: r = .59, pcorr = .002). Neural underpinnings of SA-task revealed regions involved in visual-processing and higher-order cognition. PRAA was primarily underpinned at frontal-temporal areas and functionally connected to SA-task regions pertaining to the emotional regulation. PRAFA has correlated with limbic and parietal regions, which are involved in integration of visual, emotion, and memory information of SA-task. Conclusion The results suggest a strong association of reaction time with SA-task and PRAFA and strongly support the hypothesis that PRAFA, PRAA, and associated neural mechanisms significantly influence the outcome of SA-task. Application It is beneficial to study the effect of pretask resting information on SA-task to improve SA.
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Teng, J., J. Ong, A. Patanaik, J. Zhou, M. Chee e J. Lim. "0143 Vigilance Declines Following Sleep Deprivation are Associated with Two Previously Identified Dynamic Connectivity States". Sleep 43, Supplement_1 (abril de 2020): A56—A57. http://dx.doi.org/10.1093/sleep/zsaa056.141.
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Abstract Introduction Dynamic functional connectivity (DFC) analysis of resting-state fMRI data has been successfully used to track fluctuations in arousal in the human brain. Changes in DFC have also been reported with acute sleep deprivation. Here, we demonstrate that dynamic connectivity states (DCS) previously related to arousal are reproducible, and are associated with individual differences in sustained attention declines after one night of total sleep deprivation. Methods 32 participants underwent two counterbalanced resting-state fMRI scans: during rested wakefulness (RW) and following total sleep deprivation (SD). They also completed the Psychomotor Vigilance Test (PVT), a sustained attention task that is highly sensitive to the effects of sleep loss. SD vulnerability was computed as the decrease in response speed (∆RS) and increase in lapses (∆lapse) in SD compared with RW. Dynamic functional connectivity analysis was conducted on rs-fMRI data. Connectivity matrices were clustered to obtain 5 prototypical DCS. We calculated the proportion of time participants spent in each of these DCS, as well as how often participants transitioned between DCSs. Relationships between SD vulnerability and connectivity metrics were then correlated. Results We recovered two DCS that were highly similar (ρ = .89-.91) to arousal-related DCS observed in previous work (high arousal state (HAS); low arousal state (LAS)). After sleep deprivation, the proportion of time spent in the LAS increased significantly (t29=3.16, p=.0039), while there was no significant change in HAS (t29=-1.43, p=.16). We observed significantly more state transitions in RW compared with SD. Change in LAS and HAS across sleep conditions correlated significantly with SD vulnerability (ΔLASxΔRS: r=-0.64, p<.0001; ΔLASxΔlapse: r=0.43, p=.018; ΔHASxΔRS; r=0.43, p=.019; ΔHASxΔlapse; r=-0.39, p=.033). Finally, Δ%transitions was correlated with ΔRS but not Δlapse. Conclusion This study adds to the evidence that two specific reproducible DCS are robust markers of arousal and attention, and may be useful indicators of SD vulnerability. Support This work was supported by the National Medical Research Council, Singapore (STaR/0015/2013), and the National Research Foundation Science of Learning (NRF2016-SOL002-001).
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Cline, Trey, Nicole Colgrove, Matthew Bush, Jessica Lee, David Powell, Anders Andersen, Jeffrey Weihing, Frank Musiek e Jennifer Shinn. "Behavioral and Hemodynamic Changes Following Dichotic Training in Patients with Neurological Deficits of the Auditory Nervous System: A Case Series". Journal of the American Academy of Audiology 32, n.º 01 (janeiro de 2021): 045–53. http://dx.doi.org/10.1055/s-0040-1719095.
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Abstract Background Dichotic listening occurs when one attends to different acoustical messages presented simultaneously to both ears. This is important for understanding speech in compromised listening situations, such as background noise. Deficits in dichotic listening can be remediated by participating in auditory training. We present two patients with binaural integration deficits who underwent dichotic interaural intensity difference (DIID) training. Purpose The purpose of this investigation is to demonstrate improvement of dichotic listening deficits following DIID training in neurological patients seen clinically for hearing issues. Research Design This was a case series utilizing a pre- and posttreatment design. Study Sample This case series utilized two female participants who demonstrated binaural integration deficits during an auditory processing evaluation. Intervention The participants underwent a pretraining auditory processing evaluation and functional magnetic resonance imaging (fMRI). Participants then underwent 12, 30-minute DIID training sessions followed by posttreatment auditory processing evaluations and fMRI. Data Collection and Analysis Data was collected at the pretreatment appointment and then immediately following the completion of the training. Results Each patient demonstrated varying degrees of improvement on the posttreatment assessment. Case 1 showed significant improvement on the Speech-in-Noise-Revised (SPIN-R) test. fMRI showed changes in activation patterns following training. Case 2 demonstrated improved scores on the Dichotic Digits Test and SPIN-R and increased activation of the calcarine sulcus following training. Conclusion Dichotic training can be an efficacious treatment for binaural integration deficits and may show evidence of improving speech understanding in noise. This case series demonstrates a promising therapy to help patients improve auditory function by improving dichotic listening skills.
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Omisade, Antonina, Christopher B. O’Grady, Matthias H. Schmidt e John D. Fisk. "Visual and Auditory fMRI Paradigms for Presurgical Language Mapping: Convergent Validity and Relationship to Individual Variables". Neurology Research International 2019 (1 de abril de 2019): 1–9. http://dx.doi.org/10.1155/2019/6728120.
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Functional MRI (fMRI) has emerged as a safe alternative to invasive procedures for determining hemispheric language dominance prior to neurosurgery. Despite this, there are currently no standardized fMRI protocols that have been explored in healthy controls to determine the influence of individual patient variables on the results, which poses challenges in clinical interpretation of ambiguous findings in patient populations. In addition, most fMRI protocols are not suitable for individuals with visual or intellectual disabilities (IQ<70). In the current study, 61 healthy adults (ages: 18-74 years) completed two fMRI paradigms for language mapping. One paradigm used visually based stimuli and has shown good face validity to date in our center. The second paradigm used auditory stimuli presented at slowed speed and was designed for individuals with visual or cognitive dysfunction but has not yet been used clinically. The paradigms demonstrated 97% agreement in classifying individuals as left-hemisphere, right-hemisphere, and bilaterally dominant. Cases that were classified differently showed bilateral dominance in response to either paradigm. Dominance classification rates for right- and left-handed individuals were largely in keeping with published data. Within the left-handed group, IQ and education were positively correlated with laterality indices generated by both paradigms (r values range: 0.44-0.95, p<0.01), suggesting that individuals with higher IQ and formal education were more likely to be classified as left-hemisphere dominant in the current sample. This study will help improve clinical interpretation of language fMRI maps by identifying factors that might impact results (like IQ). It also offers an alternative paradigm to make this procedure more accessible to a broader range of patients. Future studies will replicate results with a sample of patients with epilepsy across a broad range of intellectual abilities.
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Vidoni, Eric D., Matthew R. Gayed, Robyn A. Honea, Cary R. Savage, Derek Hobbs e Jeffrey M. Burns. "Alzheimer Disease Alters the Relationship of Cardiorespiratory Fitness With Brain Activity During the Stroop Task". Physical Therapy 93, n.º 7 (1 de julho de 2013): 993–1002. http://dx.doi.org/10.2522/ptj.20120465.
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Background Despite mounting evidence that physical activity has positive benefits for brain and cognitive health, there has been little characterization of the relationship between cardiorespiratory (CR) fitness and cognition-associated brain activity as measured by functional magnetic resonance imaging (fMRI). The lack of evidence is particularly glaring for diseases such as Alzheimer disease (AD) that degrade cognitive and functional performance. Objective The aim of this study was to describe the relationship between regional brain activity during cognitive tasks and CR fitness level in people with and without AD. Design A case-control, single-observation study design was used. Methods Thirty-four individuals (18 without dementia and 16 in the earliest stages of AD) completed maximal exercise testing and performed a Stroop task during fMRI. Results Cardiorespiratory fitness was inversely associated with anterior cingulate activity in the participants without dementia (r=−.48, P=.05) and unassociated with activation in those with AD (P>.7). Weak associations of CR fitness and middle frontal cortex were noted. Limitations The wide age range and the use of a single task in fMRI rather than multiple tasks challenging different cognitive capacities were limitations of the study. Conclusions The results offer further support of the relationship between CR fitness and regional brain activity. However, this relationship may be attenuated by disease. Future work in this area may provide clinicians and researchers with interpretable and dependable regional fMRI biomarker signatures responsive to exercise intervention. It also may shed light on mechanisms by which exercise can support cognitive function.
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Babaei, Arash, B. Douglas Ward, Shahryar Ahmad, Anna Patel, Andrew Nencka, Shi-Jiang Li, James Hyde e Reza Shaker. "Reproducibility of swallow-induced cortical BOLD positive and negative fMRI activity". American Journal of Physiology-Gastrointestinal and Liver Physiology 303, n.º 5 (1 de setembro de 2012): G600—G609. http://dx.doi.org/10.1152/ajpgi.00167.2012.
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Functional MRI (fMRI) studies have demonstrated that a number of brain regions (cingulate, insula, prefrontal, and sensory/motor cortices) display blood oxygen level-dependent (BOLD) positive activity during swallow. Negative BOLD activations and reproducibility of these activations have not been systematically studied. The aim of our study was to investigate the reproducibility of swallow-related cortical positive and negative BOLD activity across different fMRI sessions. We studied 16 healthy volunteers utilizing an fMRI event-related analysis. Individual analysis using a general linear model was used to remove undesirable signal changes correlated with motion, white matter, and cerebrospinal fluid. The group analysis used a mixed-effects multilevel model to identify active cortical regions. The volume and magnitude of a BOLD signal within each cluster was compared between the two study sessions. All subjects showed significant clustered BOLD activity within the known areas of cortical swallowing network across both sessions. The cross-correlation coefficient of percent fMRI signal change and the number of activated voxels across both positive and negative BOLD networks were similar between the two studies ( r ≥ 0.87, P < 0.0001). Swallow-associated negative BOLD activity was comparable to the well-defined “default-mode” network, and positive BOLD activity had noticeable overlap with the previously described “task-positive” network. Swallow activates two parallel cortical networks. These include a positive and a negative BOLD network, respectively, correlated and anticorrelated with swallow stimulus. Group cortical activity maps, as well as extent and amplitude of activity induced by volitional swallowing in the cortical swallowing network, are reproducible between study sessions.
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Assmus, Ann, Carsten Giessing, Peter H. Weiss e Gereon R. Fink. "Functional Interactions during the Retrieval of Conceptual Action Knowledge: An fMRI Study". Journal of Cognitive Neuroscience 19, n.º 6 (junho de 2007): 1004–12. http://dx.doi.org/10.1162/jocn.2007.19.6.1004.
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Impaired retrieval of conceptual knowledge for actions has been associated with lesions of left premotor, left parietal, and left middle temporal areas [Tranel, D., Kemmerer, D., Adolphs, R., Damasio, H., & Damasio, A. R. Neural correlates of conceptual knowledge for actions. Cognitive Neuropsychology, 409–432, 2003]. Here we aimed at characterizing the differential contribution of these areas to the retrieval of conceptual knowledge about actions. During functional magnetic resonance imaging (fMRI), different categories of pictograms (whole-body actions, manipulable and nonmanipulable objects) were presented to healthy subjects. fMRI data were analyzed using SPM2. A conjunction analysis of the neural activations elicited by all pictograms revealed ( p < .05, corrected) a bilateral inferior occipito-temporal neural network with strong activations in the right and left fusiform gyri. Action pictograms contrasted to object pictograms showed differential activation of area MT+, the inferior and superior parietal cortex, and the premotor cortex bilaterally. An analysis of psychophysiological interactions identified contribution-dependent changes in the neural responses when pictograms triggered the retrieval of conceptual action knowledge: Processing of action pictograms specifically enhanced the neural interaction between the right and left fusiform gyri, the right and left middle temporal cortices (MT+), and the left superior and inferior parietal cortex. These results complement and extend previous neuropsychological and neuroimaging studies by showing that knowledge about action concepts results from an increased coupling between areas concerned with semantic processing (fusiform gyrus), movement perception (MT+), and temporospatial movement control (left parietal cortex).
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Loane, Clare, Georgios P. D. Argyropoulos, Adriana Roca-Fernández, Carmen Lage, Fintan Sheerin, Samrah Ahmed, Giovanna Zamboni, Clare Mackay, Sarosh R. Irani e Christopher R. Butler. "Hippocampal network abnormalities explain amnesia after VGKCC-Ab related autoimmune limbic encephalitis". Journal of Neurology, Neurosurgery & Psychiatry 90, n.º 9 (9 de maio de 2019): 965–74. http://dx.doi.org/10.1136/jnnp-2018-320168.
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ObjectiveLimbic encephalitis associated with antibodies to components of the voltage-gated potassium channel complex (VGKCC-Ab-LE) often leads to hippocampal atrophy and persistent memory impairment. Its long-term impact on regions beyond the hippocampus, and the relationship between brain damage and cognitive outcome, are poorly understood. We investigated the nature of structural and functional brain abnormalities following VGKCC-Ab-LE and its role in residual memory impairment.MethodA cross-sectional group study was conducted. Twenty-four VGKCC-Ab-LE patients (20 male, 4 female; mean (SD) age 63.86 (11.31) years) were recruited post-acutely along with age- and sex-matched healthy controls for neuropsychological assessment, structural MRI and resting-state functional MRI (rs-fMRI). Structural abnormalities were determined using volumetry and voxel-based morphometry; rs-fMRI data were analysed to investigate hippocampal functional connectivity (FC). Associations of memory performance with neuroimaging measures were examined.ResultsPatients showed selective memory impairment. Structural analyses revealed focal hippocampal atrophy within the medial temporal lobes, correlative atrophy in the mediodorsal thalamus, and additional volume reduction in the posteromedial cortex. There was no association between regional volumes and memory performance. Instead, patients demonstrated reduced posteromedial cortico-hippocampal and inter-hippocampal FC, which correlated with memory scores (r = 0.553; r = 0.582, respectively). The latter declined as a function of time since the acute illness (r = -0.531).ConclusionVGKCC-Ab-LE results in persistent isolated memory impairment. Patients have hippocampal atrophy with further reduced mediodorsal thalamic and posteromedial cortical volumes. Crucially, reduced FC of remaining hippocampal tissue correlates more closely with memory function than does regional atrophy.
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Schröder, J., F. Wenz, L. R. Schad, K. Baudendistel e M. V. Knopp. "Sensorimotor Cortex and Supplementary Motor Area Changes in Schizophrenia". British Journal of Psychiatry 167, n.º 2 (agosto de 1995): 197–201. http://dx.doi.org/10.1192/bjp.167.2.197.
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BackgroundNeurological soft signs (NSS) such as a disturbed finger-to-thumb opposition are frequently found in schizophrenia. To identify the underlying cerebral changes we investigated sensorimotor cortex and supplementary motor area (SMA) activation during finger-to-thumb opposition using functional magnetic resonance imaging (fMRI).MethodTen DSM–III–R schizophrenics and seven healthy controls were included. All subjects were right-handed. fMRI was carried out in a resting condition followed by an activation state (finger-to-thumb opposition) and the activities in the sensorimotor cortices and SMA recorded.ResultsAll subjects showed a significant activation of the SMA and both ipsilateral and contralateral sensorimotor cortices. In the controls, ipsilateral finger-to-thumb opposition was associated with a greater left than right hemispheric sensorimotor cortex coactivation. When compared with the healthy controls, the schizophrenic patients showed a decreased activation of both sensorimotor cortices and SMA, as well as a reversed lateralisation effect.ConclusionSensorimotor cortex and SMA dysfunction are associated with motor disturbances in schizophrenia.
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Okonkwo, Ozioma C., Jennifer M. Oh, Rebecca Koscik, Erin Jonaitis, Caitlin A. Cleary, N. Maritza Dowling, Barbara B. Bendlin et al. "Amyloid Burden, Neuronal Function, and Cognitive Decline in Middle-Aged Adults at Risk for Alzheimer's Disease". Journal of the International Neuropsychological Society 20, n.º 4 (11 de março de 2014): 422–33. http://dx.doi.org/10.1017/s1355617714000113.
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AbstractThe relative influence of amyloid burden, neuronal structure and function, and prior cognitive performance on prospective memory decline among asymptomatic late middle-aged individuals at risk for Alzheimer's disease (AD) is currently unknown. We investigated this using longitudinal cognitive data from 122 middle-aged adults (21 “Decliners” and 101 “Stables”) enrolled in the Wisconsin Registry for Alzheimer's Prevention who underwent multimodality neuroimaging [11C-Pittsburgh Compound B (PiB), 18F-fluorodeoxyglucose (FDG), and structural/functional magnetic resonance imaging (fMRI)] 5.7 ± 1.4 years (range = 2.9–8.9) after their baseline cognitive assessment. Covariate-adjusted regression analyses revealed that the only imaging measure that significantly distinguished Decliners from Stables (p = .027) was a Neuronal Function composite derived from FDG and fMRI. In contrast, several cognitive measures, especially those that tap episodic memory, significantly distinguished the groups (p's<.05). Complementary receiver operating characteristic curve analyses identified the Brief Visuospatial Memory Test-Revised (BVMT-R) Total (.82 ± .05, p < .001), the BVMT-R Delayed Recall (.73 ± .06, p = .001), and the Reading subtest from the Wide-Range Achievement Test-III (.72 ± .06, p = .002) as the top three measures that best discriminated the groups. These findings suggest that early memory test performance might serve a more clinically pivotal role in forecasting future cognitive course than is currently presumed. (JINS, 2014, 20, 1–12)