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1
Moustafa EM Radwan. "Cortical Laminar necrosis in a patient with chronic cerebral infarction; Case report." World Journal of Advanced Research and Reviews 8, no. 2 (2020): 095–98. http://dx.doi.org/10.30574/wjarr.2020.8.2.0407.
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Cortical laminar necrosis (CLN) is a persistent ischemic injury attributed to a particular pan necrosis of the cerebral cortex (comprising neurons, glia, and blood vessels although underline white matter is totally or partially spared). CLN is represented radiologically by the typical curvilinear gyriform distribution high signal intensity cortical lesions on T1 weighted MRI images in the affected cerebral convolutions. This is a case of cortical laminar necrosis following old left temporo-parietal ischemic infarction. A 67-year male patient with a prior history of old left temporo-parietal ischemic infarction came for follow up MRI for old right-sided hemiplegia and aphasia. He was diabetic and hypertensive. MRI Brain images showed large old left temporo-parietal ischemic infarction in the territory of Lt. MCA. There is associated subacute ischemic infarct at the left occipital cortex. There is laminar linear cortical hyperintensity in T1WI following gyral distribution, accompanied by loss of the volume of the underlying cortex at the left temporo-parieto-occipital region suggesting cortical laminar necrosis and this picture appeared two months following old cerebral infarction and shortly the patient died.
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Moustafa, EM Radwan. "Cortical Laminar necrosis in a patient with chronic cerebral infarction; Case report." World Journal of Advanced Research and Reviews 8, no. 2 (2020): 095–98. https://doi.org/10.5281/zenodo.4318494.
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Cortical laminar necrosis (CLN) is a persistent ischemic injury attributed to a particular pan necrosis of the cerebral cortex (comprising neurons, glia, and blood vessels although underline white matter is totally or partially spared). CLN is represented radiologically by the typical curvilinear gyriform distribution high signal intensity cortical lesions on T1 weighted MRI images in the affected cerebral convolutions. This is a case of cortical laminar necrosis following old left temporo-parietal ischemic infarction. A 67-year male patient with a prior history of old left temporo-parietal ischemic infarction came for follow up MRI for old right-sided hemiplegia and aphasia. He was diabetic and hypertensive. MRI Brain images showed large old left temporo-parietal ischemic infarction in the territory of Lt. MCA. There is associated subacute ischemic infarct at the left occipital cortex. There is laminar linear cortical hyperintensity in T1WI following gyral distribution, accompanied by loss of the volume of the underlying cortex at the left temporo-parieto-occipital region suggesting cortical laminar necrosis and this picture appeared two months following old cerebral infarction and shortly the patient died.
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Ruff, Christian C., Felix Blankenburg, Otto Bjoertomt, Sven Bestmann, Nikolaus Weiskopf, and Jon Driver. "Hemispheric Differences in Frontal and Parietal Influences on Human Occipital Cortex: Direct Confirmation with Concurrent TMS–fMRI." Journal of Cognitive Neuroscience 21, no. 6 (2009): 1146–61. http://dx.doi.org/10.1162/jocn.2009.21097.
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We used concurrent TMS–fMRI to test directly for hemispheric differences in causal influences of the right or left fronto-parietal cortex on activity (BOLD signal) in the human occipital cortex. Clinical data and some behavioral TMS studies have been taken to suggest right-hemisphere specialization for top–down modulation of vision in humans, based on deficits such as spatial neglect or extinction in lesioned patients, or findings that TMS to right (vs. left) fronto-parietal structures can elicit stronger effects on visual performance. But prior to the recent advent of concurrent TMS and neuroimaging, it was not possible to directly examine the causal impact of one (stimulated) brain region upon others in humans. Here we stimulated the frontal or intraparietal cortex in the left or right hemisphere with TMS, inside an MR scanner, while measuring with fMRI any resulting BOLD signal changes in visual areas V1–V4 and V5/MT+. For both frontal and parietal stimulation, we found clear differences between effects of right- versus left-hemisphere TMS on activity in the visual cortex, with all differences significant in direct statistical comparisons. Frontal TMS over either hemisphere elicited similar BOLD decreases for central visual field representations in V1–V4, but only right frontal TMS led to BOLD increases for peripheral field representations in these regions. Hemispheric differences for effects of parietal TMS were even more marked: Right parietal TMS led to strong BOLD changes in V1–V4 and V5/MT+, but left parietal TMS did not. These data directly confirm that the human frontal and parietal cortex show right-hemisphere specialization for causal influences on the visual cortex.
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Rushworth, M. "The left parietal cortex and motor attention." Neuropsychologia 35, no. 9 (1997): 1261–73. http://dx.doi.org/10.1016/s0028-3932(97)00050-x.
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Garcea, Frank E., Jorge Almeida, Maxwell H. Sims, et al. "Domain-Specific Diaschisis: Lesions to Parietal Action Areas Modulate Neural Responses to Tools in the Ventral Stream." Cerebral Cortex 29, no. 7 (2018): 3168–81. http://dx.doi.org/10.1093/cercor/bhy183.
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Abstract Neural responses to small manipulable objects (“tools”) in high-level visual areas in ventral temporal cortex (VTC) provide an opportunity to test how anatomically remote regions modulate ventral stream processing in a domain-specific manner. Prior patient studies indicate that grasp-relevant information can be computed about objects by dorsal stream structures independently of processing in VTC. Prior functional neuroimaging studies indicate privileged functional connectivity between regions of VTC exhibiting tool preferences and regions of parietal cortex supporting object-directed action. Here we test whether lesions to parietal cortex modulate tool preferences within ventral and lateral temporal cortex. We found that lesions to the left anterior intraparietal sulcus, a region that supports hand-shaping during object grasping and manipulation, modulate tool preferences in left VTC and in the left posterior middle temporal gyrus. Control analyses demonstrated that neural responses to “place” stimuli in left VTC were unaffected by lesions to parietal cortex, indicating domain-specific consequences for ventral stream neural responses in the setting of parietal lesions. These findings provide causal evidence that neural specificity for “tools” in ventral and lateral temporal lobe areas may arise, in part, from online inputs to VTC from parietal areas that receive inputs via the dorsal visual pathway.
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Fitzpatrick, Aoife M., Neil M. Dundon, and Kenneth F. Valyear. "Hand choice is unaffected by high frequency continuous theta burst transcranial magnetic stimulation to the posterior parietal cortex." PLOS ONE 17, no. 10 (2022): e0275262. http://dx.doi.org/10.1371/journal.pone.0275262.
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The current study used a high frequency TMS protocol known as continuous theta burst stimulation (cTBS) to test a model of hand choice that relies on competing interactions between the hemispheres of the posterior parietal cortex. Based on the assumption that cTBS reduces cortical excitability, the model predicts a significant decrease in the likelihood of selecting the hand contralateral to stimulation. An established behavioural paradigm was used to estimate hand choice in each individual, and these measures were compared across three stimulation conditions: cTBS to the left posterior parietal cortex, cTBS to the right posterior parietal cortex, or sham cTBS. Our results provide no supporting evidence for the interhemispheric competition model. We find no effects of cTBS on hand choice, independent of whether the left or right posterior parietal cortex was stimulated. Our results are nonetheless of value as a point of comparison against prior brain stimulation findings that, in contrast, provide evidence for a causal role for the posterior parietal cortex in hand choice.
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Wei, Pengxu, and Ruixue Bao. "The Role of Insula-Associated Brain Network in Touch." BioMed Research International 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/734326.
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The insula is believed to be associated with touch-evoked effects. In this work, functional MRI was applied to investigate the network model of insula function when 20 normal subjects received tactile stimulation over segregated areas. Data analysis was performed with SPM8 and Conn toolbox. Activations in the contralateral posterior insula were consistently revealed for all stimulation areas, with the overlap located in area Ig2. The area Ig2 was then used as the seed to estimate the insula-associated network. The right insula, left superior parietal lobule, left superior temporal gyrus, and left inferior parietal cortex showed significant functional connectivity with the seed region for all stimulation conditions. Connectivity maps of most stimulation conditions were mainly distributed in the bilateral insula, inferior parietal cortex, and secondary somatosensory cortex. Post hoc ROI-to-ROI analysis and graph theoretical analysis showed that there were higher correlations between the left insula and the right insula, left inferior parietal cortex and right OP1 for all networks and that the global efficiency was more sensitive than the local efficiency to detect differences between notes in a network. These results suggest that the posterior insula serves as a hub to functionally connect other regions in the detected network and may integrate information from these regions.
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Assmus, Ann, Carsten Giessing, Peter H. Weiss, and Gereon R. Fink. "Functional Interactions during the Retrieval of Conceptual Action Knowledge: An fMRI Study." Journal of Cognitive Neuroscience 19, no. 6 (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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Davranche, Karen, Bruno Nazarian, Franck Vidal, and Jennifer Coull. "Orienting Attention in Time Activates Left Intraparietal Sulcus for Both Perceptual and Motor Task Goals." Journal of Cognitive Neuroscience 23, no. 11 (2011): 3318–30. http://dx.doi.org/10.1162/jocn_a_00030.
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Attention can be directed not only toward a location in space but also to a moment in time (“temporal orienting”). Temporally informative cues allow subjects to predict when an imminent event will occur, thereby speeding responses to that event. In contrast to spatial orienting, temporal orienting preferentially activates left inferior parietal cortex. Yet, left parietal cortex is also implicated in selective motor attention, suggesting its activation during temporal orienting could merely reflect incidental engagement of preparatory motor processes. Using fMRI, we therefore examined whether temporal orienting would still activate left parietal cortex when the cued target required a difficult perceptual discrimination rather than a speeded motor response. Behaviorally, temporal orienting improved accuracy of target identification as well as speed of target detection, demonstrating the general utility of temporal cues. Crucially, temporal orienting selectively activated left inferior parietal cortex for both motor and perceptual versions of the task. Moreover, conjunction analysis formally revealed a region deep in left intraparietal sulcus (IPS) as common to both tasks, thereby identifying it as a core neural substrate for temporal orienting. Despite the context-independent nature of left IPS activation, complementary psychophysiological interaction analysis revealed how the functional connectivity of left IPS changed as a function of task context. Specifically, left IPS activity covaried with premotor activity during motor temporal orienting but with visual extrastriate activity during perceptual temporal orienting, thereby revealing a cooperative network that comprises both temporal orienting and task-specific processing nodes.
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Breveglieri, Rossella, Sara Borgomaneri, Matteo Filippini, Marina De Vitis, Alessia Tessari, and Patrizia Fattori. "Functional Connectivity at Rest between the Human Medial Posterior Parietal Cortex and the Primary Motor Cortex Detected by Paired-Pulse Transcranial Magnetic Stimulation." Brain Sciences 11, no. 10 (2021): 1357. http://dx.doi.org/10.3390/brainsci11101357.
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The medial posterior parietal cortex (PPC) is involved in the complex processes of visuomotor integration. Its connections to the dorsal premotor cortex, which in turn is connected to the primary motor cortex (M1), complete the fronto-parietal network that supports important cognitive functions in the planning and execution of goal-oriented movements. In this study, we wanted to investigate the time-course of the functional connectivity at rest between the medial PPC and the M1 using dual-site transcranial magnetic stimulation in healthy humans. We stimulated the left M1 using a suprathreshold test stimulus to elicit motor-evoked potentials in the hand, and a subthreshold conditioning stimulus was applied over the left medial PPC at different inter-stimulus intervals (ISIs). The conditioning stimulus affected the M1 excitability depending on the ISI, with inhibition at longer ISIs (12 and 15 ms). We suggest that these modulations may reflect the activation of different parieto-frontal pathways, with long latency inhibitions likely recruiting polisynaptic pathways, presumably through anterolateral PPC.
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Bakulin, I. S., A. H. Zabirova, P. N. Kopnin, et al. "Cerebral cortex activation during the Sternberg verbal working memory task." Bulletin of Russian State Medical University, no. (1)2020 (February 29, 2020): 40–48. http://dx.doi.org/10.24075/brsmu.2020.013.
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Despite intensive study, the data regarding functional role of specific brain regions in the working memory processes still remain controversial. The study was aimed to determine the activation of cerebral cortex regions at different stages of the working memory task (information encoding, maintenance and retrieval). Functional magnetic resonance imaging (fMRI) with the modified Sternberg task was applied to 19 healthy volunteers. The objective of the task was to memorize and retain in memory the sequence of 7 letters with the subsequent comparison of one letter with the sequence. Activation was analyzed during three periods of the task compared to the rest period, as well as temporal dynamics of changes in BOLD signal intensity in three regions: left dorsolateral prefrontal, left posterior parietal and left occipital cortex. According to the results, significant activation of the regions in prefrontal and posterior parietal cortex was observed during all periods of the task (p < 0.05), but there were changes in its localization and lateralization. The activation pattern during the maintenance period corresponded to the fronto-parietal control network components. According to the analysis of temporal dynamics of changes in BOLD signal intensity, the most prominent activation of the dorsolateral prefrontal cortex and parietal cortex was observed in the end of the encoding period, during the maintenance period and in the beginning of the retrieval period, which confirmed the role of those areas in the working memory processes. The maximum of occipital cortex activation was observed during encoding period. The study confirmed the functional role of the dorsolateral prefrontal cortex and posterior parietal cortex in the working memory mechanisms during all stages of the Sternberg task.
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Wiener, Martin, Peter E. Turkeltaub, and H. Branch Coslett. "Implicit timing activates the left inferior parietal cortex." Neuropsychologia 48, no. 13 (2010): 3967–71. http://dx.doi.org/10.1016/j.neuropsychologia.2010.09.014.
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Berthoz, Alain. "Parietal and hippocampal contribution to topokinetic and topographic memory." Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 352, no. 1360 (1997): 1437–48. http://dx.doi.org/10.1098/rstb.1997.0130.
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This paper reviews the involvement of the parietal cortex and the hippocampus in three kinds of spatial memory tasks which all require a memory of a previously experienced movement in space. The first task compared, by means of positron emission tomography (PET) scan techniques, the production, in darkness, of self–paced saccades (SAC) with the reproduction, in darkness, of a previously learned sequence of saccades to visual targets (SEQ). The results show that a bilateral increase of activity was seen in the depth of the intraparietal sulcus and the medial superior parietal cortex (superior parietal gyrus and precuneus) together with the frontal sulcus but only in the SEQ task, which involved memory of the previously seen targets and possibly also motor memory. The second task is the vestibular memory contingent task, which requires that the subject makes, in darkness, a saccade to the remembered position of a visual target after a passively imposed whole–body rotation. Deficits in this task, which involves ‘vestibular memory’, were found predominantly in patients with focal vascular lesions in the parieto–insular (vestibular) cortex, the supplementary motor area–supplementary eye field area, and the prefrontal cortex. The third task requires mental navigation from the memory of a previously learned route in a real environment (the city of Orsay in France). A PET scan study has revealed that when subjects were asked to remember visual landmarks there was a bilateral activation of the middle hippocampal regions, left inferior temporal gyrus, left hippocampal regions, precentral gyrus and posterior cingulate gyrus. If the subjects were asked to remember the route, and their movements along this route, bilateral activation of the dorsolateral cortex, posterior hippocampal areas, posterior cingulate gyrus, supplementary motor areas, right middle hippocampal areas, left precuneus, middle occipital gyrus, fusiform gyrus and lateral premotor area was found. Subtraction between the two conditions reduced the activated areas to the left hippocampus, precuneus and insula. These data suggest that the hippocampus and parietal cortex are both involved in the dynamic aspects of spatial memory, for which the name ’topokinetic memory’ is proposed. These dynamic aspects could both overlap and be different from those involved in the cartographic and static aspects of ‘topographic’ memory.
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Schroeder, J., M. S. Buchsbaum, B. V. Siegel, et al. "Patterns of cortical activity in schizophrenia." Psychological Medicine 24, no. 4 (1994): 947–55. http://dx.doi.org/10.1017/s0033291700029032.
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SynopsisEighty-three patients with schizophrenia and 47 healthy controls received positron emission tomography (PET) with 18F-2-deoxyglucose uptake while they were executing the Continuous Performance Test (CPT). The entire cortex was divided into 16 regions of interest in each hemisphere, four in each lobe of the brain, and data from corresponding right and left hemispheric regions were averaged. Data from the schizophrenic patients were subjected to a factor analysis, which revealed five factors that explained 80% of the common variance. According to their content, the factors were identified and labelled ‘parietal cortex and motor strip’, ‘associative areas’, ‘temporal cortex’, ‘hypofrontality’ (which included midfrontal and occipital areas) and ‘frontal cortex’. Hemispheric asymmetry was only confirmed for the temporal cortex. Factor weights obtained in the schizophrenic group were applied to the metabolic data of the healthy controls and factor scales computed. Schizophrenics were significantly more hypofrontal than the controls, with higher values on the ‘parietal cortex and motor strip’ factor and a trend towards higher values in the temporal cortex. A canonical discriminant analysis confirmed that the ‘hypofrontality’ and ‘parietal cortex and motor strip’ factors accurately separated the schizophrenic group from the healthy controls. Hemispheric asymmetry was only confirmed for the temporal lobe. Significantly higher factor scores for the left temporal lobe in schizophrenics than in normals were obtained when calculated for the right and left hemisphere separately. Taken together, our results confirm the importance of hypofrontality as a pattern of cortical metabolic rate and point to the potential importance of parietal and motor strip function in schizophrenia.
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Haaland, Kathleen Y., Catherine L. Elsinger, Andrew R. Mayer, Sally Durgerian, and Stephen M. Rao. "Motor Sequence Complexity and Performing Hand Produce Differential Patterns of Hemispheric Lateralization." Journal of Cognitive Neuroscience 16, no. 4 (2004): 621–36. http://dx.doi.org/10.1162/089892904323057344.
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Studies in brain damaged patients conclude that the left hemisphere is dominant for controlling heterogeneous sequences performed by either hand, presumably due to the cognitive resources involved in planning complex sequential movements. To determine if this lateralized effect is due to asymmetries in primary sensorimotor or association cortex, whole-brain functional magnetic resonance imaging was used to measure differences in volume of activation while healthy right-handed subjects performed repetitive (simple) or heterogeneous (complex) finger sequences using the right or left hand. Advanced planning, as evidenced by reaction time to the first key press, was greater for the complex than simple sequences and for the left than right hand. In addition to the expected greater contralateral activation in the sensorimotor cortex (SMC), greater left hemisphere activation was observed for left, relative to right, hand movements in the ipsilateral left superior parietal area and for complex, relative to simple, sequences in the left premotor and parietal cortex, left thalamus, and bilateral cerebellum. No such volumetric asymmetries were observed in the SMC. Whereas the overall MR signal intensity was greater in the left than right SMC, the extent of this asymmetry did not vary with hand or complexity level. In contrast, signal intensity in the parietal and premotor cortex was greater in the left than right hemisphere and for the complex than simple sequences. Signal intensity in the caudal anterior cerebellum was greater bilaterally for the complex than simple sequences. These findings suggest that activity in the SMC is associated with execution requirements shared by the simple and complex sequences independent of their differential cognitive requirements. In contrast, consistent with data in brain damaged patients, the left dorsal premotor and parietal areas are engaged when advanced planning is required to perform complex motor sequences that require selection of different effectors and abstract organization of the sequence, regardless of the performing hand.
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Notebaert, Karolien, Sabine Nelis, and Bert Reynvoet. "The Magnitude Representation of Small and Large Symbolic Numbers in the Left and Right Hemisphere: An Event-related fMRI Study." Journal of Cognitive Neuroscience 23, no. 3 (2011): 622–30. http://dx.doi.org/10.1162/jocn.2010.21445.
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Numbers are known to be processed along the left and right intraparietal sulcus. The present study investigated hemispheric differences between the magnitude representation of small and large symbolic numbers. To this purpose, an fMRI adaptation paradigm was used, where the continuous presentation of a habituation number was interrupted by an occasional deviant number. The results presented a distance-dependent increase of activation: larger ratios of habituation and deviant number caused a larger recovery of activation. Similar activation patterns were observed for small and large symbolic numbers, which is in line with the idea of a more coarse magnitude representation for large numbers. Interestingly, this pattern of activation was only observed in the left parietal cortex, supporting the recently proposed idea of Ansari [Ansari, D. Does the parietal cortex distinguish between “10”, “Ten,” and Ten Dots? Neuron, 53, 165–167, 2007] that the left parietal cortex is specialized in the processing of encultured symbolically presented numbers.
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Arnold, Stephan, Soheyl Noachtar, Rainer Linke, et al. "Ictal SPECT hyperperfusion reflects the activation of the symptomatogenic cortex in spontaneous and electrically‐induced non‐habitual focal epileptic seizures: correlation with subdural EEG recordings." Epileptic Disorders 2, no. 1 (2000): 41–44. http://dx.doi.org/10.1684/j.1950-6945.2000.tb00349.x.
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ABSTRACT We report a patient with left temporal lobe epilepsy and a left parietal angioma, in whom ictal SPECT showed hyperperfusion in a spontaneous and an electrically‐induced, non‐habitual focal seizure. A SPECT investigation during an habitual seizure originating in the left temporal lobe showed a left temporal hyperperfusion. Electrical stimulation of the parietal cortex adjacent to the location of a previously resected angioma using subdural electrodes resulted in a non‐habitual seizure beginning with a unilateral somatosensory aura. Ictal SPECT of this seizure demonstrated contralateral central hyperperfusion. We conclude from our findings that ictal SPECT hyperperfusion reflects the activation of symptomatogenic cortex, which can be induced by both epileptic discharge and electrical stimulation.
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Sui, Shuang Ge, Ming Xiang Wu, Mark E. King, et al. "Abnormal grey matter in victims of rape with PTSD in Mainland China: a voxel-based morphometry study." Acta Neuropsychiatrica 22, no. 3 (2010): 118–26. http://dx.doi.org/10.1111/j.1601-5215.2010.00459.x.
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Sui SG, Wu MX, King ME, Zhang Y, Ling L, Xu JM, Weng XC, Duan L, Shan BC, Li LJ. Abnormal grey matter in victims of rape with PTSD in Mainland China: a voxel-based morphometry study.Objective:This study examined changes in brain grey matter in victims of rape (VoR) with and without post-traumatic stress disorder (PTSD). Previous research has focused on PTSD caused by various traumatic events, such as war and disaster, among others. Although considerable research has focused on rape-related PTSD, limited studies have been carried out in the context of Mainland China.Methods:The study included 11 VoR with PTSD, 8 VoR without PTSD and 12 healthy comparison (HC) subjects. We used voxel-based morphometry to explore changes in brain grey-matter density (GMD) by applying statistical parametric mapping to high-resolution magnetic resonance images.Results:Compared with HC, VoR with PTSD showed significant GMD reductions in the bilateral medial frontal cortex, left middle frontal cortex, middle temporal gyrus and fusiform cortex and significant GMD increases in the right posterior cingulate cortex, postcentral cortex, bilateral precentral cortex and inferior parietal lobule. Compared to VoR without PTSD, VoR with PTSD showed significant GMD reductions in the right uncus, left middle temporal gyrus, and the fusiform cortex, and increases in the left precentral cortex, inferior parietal lobule and right post-central cortex.Conclusion:The findings of abnormal GMD in VoR with PTSD support the hypothesis that PTSD is associated with widespread anatomical changes in the brain. The medial frontal cortex, precentral cortex, posterior cingulate cortex, post-central cortex and inferior parietal lobule may play important roles in the neuropathology of PTSD.
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Vallar, Giuseppe. "Spatial Neglect, Balint-Homes' and Gerstmann's Syndrome, and Other Spatial Disorders." CNS Spectrums 12, no. 7 (2007): 527–36. http://dx.doi.org/10.1017/s1092852900021271.
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ABSTRACTBrain-damaged patients with lesion or dysfunction involving the parietal cortex may show a variety of neuropsychological impairments involving spatial cognition. The more frequent and disabling deficit is the syndrome of unilateral spatial neglect that, in a nutshell, consists in a bias of spatial representation and attention ipsilateral to of extrapersonal, personal (ie, the body) space, or both, toward the side of the hemispheric lesion. The deficit is more frequent and severe after damage to the right hemisphere, involving particularly the posterior-inferior parietal cortex at the temporo-parietal junction. Damage to these posterior parietal regions may also impair visuospatial short-term memory, which may be associated with and worsen spatial neglect. The neural network supporting spatial representation, attention and short-term memory is, however, more extensive, including the right premotor cortex. Also disorders of drawing and building objects (traditionally termed constructional apraxia) are a frequent indicator of posterior parietal damage in the left and in the right hemispheres. Other less frequent deficits, which, however, have a relevant localizing value, include optic ataxia (namely, the defective reaching of visual objects, in the absence of elementary visuo-motor impairments), which is typically brought about by damage to the superior parietal lobule. Optic ataxia, together with deficits of visual attention, of estimating distances and depth, and with apraxia of gaze, constitutes the severely disabling Balint-Holmes' syndrome, which is typically associated with bilateral posterior parietal and occipital damage. Finally, lesions of the posterior parietal lobule (angular gyrus) in the left hemisphere may bring about a tetrad of symptoms (left-right disorientation, acalculia, finger agnosia, and agraphia) termed Gerstmann's syndrome, that also exists in a developmental form.
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Wada, Makoto, Kouji Takano, Shiro Ikegami, Hiroki Ora, Charles Spence, and Kenji Kansaku. "Spatio-Temporal Updating in the Left Posterior Parietal Cortex." PLoS ONE 7, no. 6 (2012): e39800. http://dx.doi.org/10.1371/journal.pone.0039800.
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Nelson, Steven M., Alexander L. Cohen, Jonathan D. Power, et al. "A Parcellation Scheme for Human Left Lateral Parietal Cortex." Neuron 67, no. 1 (2010): 156–70. http://dx.doi.org/10.1016/j.neuron.2010.05.025.
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Bracci, Stefania, Cristiana Cavina-Pratesi, Magdalena Ietswaart, Alfonso Caramazza, and Marius V. Peelen. "Closely overlapping responses to tools and hands in left lateral occipitotemporal cortex." Journal of Neurophysiology 107, no. 5 (2012): 1443–56. http://dx.doi.org/10.1152/jn.00619.2011.
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The perception of object-directed actions performed by either hands or tools recruits regions in left fronto-parietal cortex. Here, using functional MRI (fMRI), we tested whether the common role of hands and tools in object manipulation is also reflected in the distribution of response patterns to these categories in visual cortex. In two experiments we found that static pictures of hands and tools activated closely overlapping regions in left lateral occipitotemporal cortex (LOTC). Left LOTC responses to tools selectively overlapped with responses to hands but not with responses to whole bodies, nonhand body parts, other objects, or visual motion. Multivoxel pattern analysis in left LOTC indicated a high degree of similarity between response patterns to hands and tools but not between hands or tools and other body parts. Finally, functional connectivity analysis showed that the left LOTC hand/tool region was selectively connected, relative to neighboring body-, motion-, and object-responsive regions, with regions in left intraparietal sulcus and left premotor cortex that have previously been implicated in hand/tool action-related processing. Taken together, these results suggest that action-related object properties shared by hands and tools are reflected in the organization of high-order visual cortex. We propose that the functional organization of high-order visual cortex partly reflects the organization of downstream functional networks, such as the fronto-parietal action network, due to differences within visual cortex in the connectivity to these networks.
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Martin, Ruth E., Bradley J. MacIntosh, Rebecca C. Smith, et al. "Cerebral Areas Processing Swallowing and Tongue Movement Are Overlapping but Distinct: A Functional Magnetic Resonance Imaging Study." Journal of Neurophysiology 92, no. 4 (2004): 2428–43. http://dx.doi.org/10.1152/jn.01144.2003.
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Although multiple regions of the cerebral cortex have been implicated in swallowing, the functional contributions of each brain area remain unclear. The present study sought to clarify the roles of these cortical foci in swallowing by comparing brain activation associated with voluntary saliva swallowing and voluntary tongue elevation. Fourteen healthy right-handed subjects were examined with single-event–related functional magnetic resonance imaging (fMRI) while laryngeal movements associated with swallowing and tongue movement were simultaneously recorded. Both swallowing and tongue elevation activated 1) the left lateral pericentral and anterior parietal cortex, and 2) the anterior cingulate cortex (ACC) and adjacent supplementary motor area (SMA), suggesting that these brain regions mediate processes shared by swallowing and tongue movement. Tongue elevation activated a larger total volume of cortex than swallowing, with significantly greater activation within the ACC, SMA, right precentral and postcentral gyri, premotor cortex, right putamen, and thalamus. Although a contrast analysis failed to identify activation foci specific to swallowing, superimposed activation maps suggested that the most lateral extent of the left pericentral and anterior parietal cortex, rostral ACC, precuneus, and right parietal operculum/insula were preferentially activated by swallowing. This finding suggests that these brain areas may mediate processes specific to swallowing. Approximately 60% of the subjects showed a strong functional lateralization of the postcentral gyrus toward the left hemisphere for swallowing, whereas 40% showed a similar activation bias for the tongue elevation task. This finding supports the view that the oral sensorimotor cortices within the left and right hemispheres are functionally nonequivalent.
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Leo, Andrea, Giulio Bernardi, Giacomo Handjaras, Daniela Bonino, Emiliano Ricciardi, and Pietro Pietrini. "Increased BOLD Variability in the Parietal Cortex and Enhanced Parieto-Occipital Connectivity during Tactile Perception in Congenitally Blind Individuals." Neural Plasticity 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/720278.
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Previous studies in early blind individuals posited a possible role of parieto-occipital connections in conveying nonvisual information to the visual occipital cortex. As a consequence of blindness, parietal areas would thus become able to integrate a greater amount of multimodal information than in sighted individuals. To verify this hypothesis, we compared fMRI-measured BOLD signal temporal variability, an index of efficiency in functional information integration, in congenitally blind and sighted individuals during tactile spatial discrimination and motion perception tasks. In both tasks, the BOLD variability analysis revealed many cortical regions with a significantly greater variability in the blind as compared to sighted individuals, with an overlapping cluster located in the left inferior parietal/anterior intraparietal cortex. A functional connectivity analysis using this region as seed showed stronger correlations in both tasks with occipital areas in the blind as compared to sighted individuals. As BOLD variability reflects neural integration and processing efficiency, these cross-modal plastic changes in the parietal cortex, even if described in a limited sample, reinforce the hypothesis that this region may play an important role in processing nonvisual information in blind subjects and act as a hub in the cortico-cortical pathway from somatosensory cortex to the reorganized occipital areas.
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Schumacher, Eric H., Puni A. Elston, and Mark D'Esposito. "Neural Evidence for Representation-Specific Response Selection." Journal of Cognitive Neuroscience 15, no. 8 (2003): 1111–21. http://dx.doi.org/10.1162/089892903322598085.
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Response selection is the mental process of choosing representations for appropriate motor behaviors given particular environmental stimuli and one's current task situation and goals. Many cognitive theories of response selection postulate a unitary process. That is, one central response-selection mechanism chooses appropriate responses in most, if not all, task situations. However, neuroscience research shows that neural processing is often localized based on the type of information processed. Our current experiments investigate whether response selection is unitary or stimulus specific by manipulating response-selection difficulty in two functional magnetic resonance imaging experiments using spatial and nonspatial stimuli. The same participants were used in both experiments. We found spatial response selection involves the right prefrontal cortex, the bilateral premotor cortex, and the dorsal parietal cortical regions (precuneus and superior parietal lobule). Nonspatial response selection, conversely, involves the left prefrontal cortex and the more ventral posterior cortical regions (left middle temporal gyrus, left inferior parietal lobule, and right extrastriate cortex). Our brain activation data suggest a cognitive model for response selection in which different brain networks mediate the choice of appropriate responses for different types of stimuli. This model is consistent with behavioral research suggesting that responseselection processing may be more flexible and adaptive than originally proposed.
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Skagerlund, Kenny, Taylor Bolt, Jason S. Nomi, et al. "Disentangling Mathematics from Executive Functions by Investigating Unique Functional Connectivity Patterns Predictive of Mathematics Ability." Journal of Cognitive Neuroscience 31, no. 4 (2019): 560–73. http://dx.doi.org/10.1162/jocn_a_01367.
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What are the underlying neurocognitive mechanisms that give rise to mathematical competence? This study investigated the relationship between tests of mathematical ability completed outside the scanner and resting-state functional connectivity (FC) of cytoarchitectonically defined subdivisions of the parietal cortex in adults. These parietal areas are also involved in executive functions (EFs). Therefore, it remains unclear whether there are unique networks for mathematical processing. We investigate the neural networks for mathematical cognition and three measures of EF using resting-state fMRI data collected from 51 healthy adults. Using 10 ROIs in seed to whole-brain voxel-wise analyses, the results showed that arithmetical ability was correlated with FC between the right anterior intraparietal sulcus (hIP1) and the left supramarginal gyrus and between the right posterior intraparietal sulcus (hIP3) and the left middle frontal gyrus and the right premotor cortex. The connection between the posterior portion of the left angular gyrus and the left inferior frontal gyrus was also correlated with mathematical ability. Covariates of EF eliminated connectivity patterns with nodes in inferior frontal gyrus, angular gyrus, and middle frontal gyrus, suggesting neural overlap. Controlling for EF, we found unique connections correlated with mathematical ability between the right hIP1 and the left supramarginal gyrus and between hIP3 bilaterally to premotor cortex bilaterally. This is partly in line with the “mapping hypothesis” of numerical cognition in which the right intraparietal sulcus subserves nonsymbolic number processing and connects to the left parietal cortex, responsible for calculation procedures. We show that FC within this circuitry is a significant predictor of math ability in adulthood.
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Beeram, Vamseemohan, Sundaram Challa, and Prasad Vannemreddy. "Cerebral mycetoma with cranial osteomyelitis." Journal of Neurosurgery: Pediatrics 1, no. 6 (2008): 493–95. http://dx.doi.org/10.3171/ped/2008/1/6/493.
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✓ Craniocerebral maduromycetoma is extremely rare. The authors describe a case of maduromycetoma involving the left parietal cortex, bone, and subcutaneous tissue in a young male farm laborer who presented with left parietal scalp swelling that had progressed into a relentlessly discharging sinus. Computed tomography (CT) scanning of his brain revealed osteomyelitis of the parietal bone with an underlying homogeneously enhancing tumor. Intraoperatively, the mass was revealed to be a black lesion involving the bone, dura mater, and underlying cerebral cortex. It was friable and separated from the surrounding brain by a thick gliotic scar. Gross-total excision was performed, and the patient was placed on a 6-week regimen of itraconazole. To the authors' knowledge, this is the first instance of cerebral mycetoma with CT findings reported in the literature.
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Gerschlager, Willibald, Hartwig R. Siebner, and John C. Rothwell. "Decreased corticospinal excitability after subthreshold 1 Hz rTMS over lateral premotor cortex." Neurology 57, no. 3 (2001): 449–55. http://dx.doi.org/10.1212/wnl.57.3.449.
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Objective: To study whether trains of subthreshold 1 Hz repetitive transcranial magnetic stimulation (rTMS) over premotor, prefrontal, or parietal cortex can produce changes in excitability of motor cortex that outlast the application of the train.Background: Prolonged 1 Hz rTMS over the motor cortex can suppress the amplitude of motor-evoked potentials (MEP) for several minutes after the end of the train. Because TMS can produce effects not only at the site of stimulation but also at distant sites to which it projects, the authors asked whether prolonged stimulation of sites distant but connected to motor cortex can also lead to lasting changes in MEP.Methods: Eight subjects received 1500 magnetic stimuli given at 1 Hz over the left lateral frontal cortex, the left lateral premotor cortex, the hand area of the left motor cortex, and the left anterior parietal cortex on four separate days. Stimulus intensity was set at 90% active motor threshold. Corticospinal excitability was probed by measuring the amplitude of MEP evoked in the right first dorsal interosseous muscle by single suprathreshold stimuli over the left motor hand area before, during, and after the conditioning trains.Results: rTMS over the left premotor cortex suppressed the amplitude of MEP in the right first dorsal interosseous muscle. The effect was maximized (approximately 50% suppression) after 900 pulses and outlasted the full train of 1500 stimuli for at least 15 minutes. Conditioning rTMS over the other sites did not modify the size of MEP. A control experiment showed that left premotor cortex conditioning had no effect on MEP evoked in the left first dorsal interosseous muscle.Conclusions: Subthreshold 1 Hz rTMS of the left premotor cortex induces a short-lasting inhibition of corticospinal excitability in the hand area of the ipsilateral motor cortex. This may provide a model for studying the functional interaction between premotor and motor cortex in healthy subjects and patients with movement disorders.
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Vesia, Michael, Jachin A. Monteon, Lauren E. Sergio, and J. D. Crawford. "Hemispheric Asymmetry in Memory-Guided Pointing During Single-Pulse Transcranial Magnetic Stimulation of Human Parietal Cortex." Journal of Neurophysiology 96, no. 6 (2006): 3016–27. http://dx.doi.org/10.1152/jn.00411.2006.
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Dorsal posterior parietal cortex (PPC) has been implicated through single-unit recordings, neuroimaging data, and studies of brain-damaged humans in the spatial guidance of reaching and pointing movements. The present study examines the causal effect of single-pulse transcranial magnetic stimulation (TMS) over the left and right dorsal posterior parietal cortex during a memory-guided “reach-to-touch” movement task in six human subjects. Stimulation of the left parietal hemisphere significantly increased endpoint variability, independent of visual field, with no horizontal bias. In contrast, right parietal stimulation did not increase variability, but instead produced a significantly systematic leftward directional shift in pointing (contralateral to stimulation site) in both visual fields. Furthermore, the same lateralized pattern persisted with left-hand movement, suggesting that these aspects of parietal control of pointing movements are spatially fixed. To test whether the right parietal TMS shift occurs in visual or motor coordinates, we trained subjects to point correctly to optically reversed peripheral targets, viewed through a left–right Dove reversing prism. After prism adaptation, the horizontal pointing direction for a given visual target reversed, but the direction of shift during right parietal TMS did not reverse. Taken together, these data suggest that induction of a focal current reveals a hemispheric asymmetry in the early stages of the putative spatial processing in PPC. These results also suggest that a brief TMS pulse modifies the output of the right PPC in motor coordinates downstream from the adapted visuomotor reversal, rather than modifying the upstream visual coordinates of the memory representation.
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Price, C. J., C. J. Mummery, C. J. Moore, R. S. J. Frackowiak, and K. J. Friston. "Delineating Necessary and Sufficient Neural Systems with Functional Imaging Studies of Neuropsychological Patients." Journal of Cognitive Neuroscience 11, no. 4 (1999): 371–82. http://dx.doi.org/10.1162/089892999563481.
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This paper demonstrates how functional imaging studies of neuropsychological patients can provide a way of determining which areas in a cognitive network are jointly necessary and sufficient. The approach is illustrated with an investigation of the neural system underlying semantic similarity judgments. Functional neuroimaging demonstrates that normal subjects activate left temporal, parietal, and inferior frontal cortices during this task relative to physical size judgments. Neuropsychology demonstrates that damage to the temporal and parietal regions results in semantic deficits, indicating that these areas are necessary for task performance. In contrast, damage to the inferior frontal cortex does not impair task performance, indicating that the inferior frontal cortex might not be necessary. However, there are two other possible accounts of intact performance following frontal lobe damage: (1) there is functional reorganization involving the right frontal cortex and (2) there is peri-infarct activity around the damaged left-hemisphere tissue. Functional imaging of the patient is required to discount these possibilities. We investigated a patient (SW), who was able to associate words and pictures on the basis of semantic relationships despite extensive damage to the left frontal, inferior parietal, and superior temporal cortices. Although SW showed peri-infarct activation in left extrasylvian temporal cortices, no activity was observed in either left or right inferior frontal cortices. These ªndings demonstrate that activity in extrasylvian temporo-parietal and medial superior frontal regions is sufªcient to perform semantic similarity judgments. In contrast, the left inferior frontal activations detected in each control subject appear not to be necessary for task performance. In conclusion, necessary and sufªcient brain systems can be delineated by functional imaging of brain-damaged patients who are not functionally impaired.
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Lyons, Ian M., and Daniel Ansari. "The Cerebral Basis of Mapping Nonsymbolic Numerical Quantities onto Abstract Symbols: An fMRI Training Study." Journal of Cognitive Neuroscience 21, no. 9 (2009): 1720–35. http://dx.doi.org/10.1162/jocn.2009.21124.
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Although significant insights into the neural basis of numerical and mathematical processing have been made, the neural processes that enable abstract symbols to become numerical remain largely unexplored in humans. In the present study, adult participants were trained to associate novel symbols with nonsymbolic numerical magnitudes (arrays of dots). Functional magnetic resonance imaging was used to examine the neural correlates of numerical comparison versus recognition of the novel symbols after each of two training stages. A left-lateralized fronto-parietal network, including the intraparietal sulcus, the precuneus, and the dorsal prefrontal cortex, was more active during numerical comparison than during perceptual recognition. In contrast, a network including bilateral temporal–occipital regions was more active during recognition than comparison. A whole-brain three-way interaction revealed that those individuals who had higher scores on a postscan numerical task (measuring their understanding of the global numerical organization of the novel symbols) exhibited increasing segregation between the two tasks in the bilateral intraparietal sulci as a function of increased training. Furthermore, whole-brain regression analysis showed that activity in the left intraparietal sulcus was systematically related to the effect of numerical distance on accuracy. These data provide converging evidence that parietal and left prefrontal cortices are involved in learning to map numerical quantities onto visual symbols. Only the parietal cortex, however, appeared systematically related to the degree to which individuals learned to associate novel symbols with their numerical referents. We conclude that the left parietal cortex, in particular, may play a central role in imbuing visual symbols with numerical meaning.
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Malfait, Nicole, Kenneth F. Valyear, Jody C. Culham, Jean-Luc Anton, Liana E. Brown, and Paul L. Gribble. "fMRI Activation during Observation of Others' Reach Errors." Journal of Cognitive Neuroscience 22, no. 7 (2010): 1493–503. http://dx.doi.org/10.1162/jocn.2009.21281.
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When exposed to novel dynamical conditions (e.g., externally imposed forces), neurologically intact subjects easily adjust motor commands on the basis of their own reaching errors. Subjects can also benefit from visual observation of others' kinematic errors. Here, using fMRI, we scanned subjects watching movies depicting another person learning to reach in a novel dynamic environment created by a robotic device. Passive observation of reaching movements (whether or not they were perturbed by the robot) was associated with increased activation in fronto-parietal regions that are normally recruited in active reaching. We found significant clusters in parieto-occipital cortex, intraparietal sulcus, as well as in dorsal premotor cortex. Moreover, it appeared that part of the network that has been shown to be engaged in processing self-generated reach error is also involved in observing reach errors committed by others. Specifically, activity in left intraparietal sulcus and left dorsal premotor cortex, as well as in right cerebellar cortex, was modulated by the amplitude of observed kinematic errors.
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Schiff, Sami, Lara Bardi, Demis Basso, and Daniela Mapelli. "Timing Spatial Conflict within the Parietal Cortex: A TMS Study." Journal of Cognitive Neuroscience 23, no. 12 (2011): 3998–4007. http://dx.doi.org/10.1162/jocn_a_00080.
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Orienting and motor attention are known to recruit different regions within right and left parietal lobes. However, the time course and the role played by these modules when visual information competes for different motor response are still unknown. To deal with this issue, single-pulse TMS was applied over the angular (AG) and the supramarginal (SMG) gyri of both hemispheres at several time intervals during the execution of a Simon task. Suppression of the conflict between stimulus and response positions (i.e., the Simon effect) was found when TMS pulse was applied 130 msec after stimulus onset over the right AG and after 160 msec when applied over the left AG and SMG. Interestingly, only stimulation of the left SMG suppressed the asymmetry in conflict magnitude between left- and right-hand responses, usually observed in the Simon task. The present data show that orienting attention and motor attention processes are temporally, functionally, and spatially separated in the posterior parietal cortex, and both contribute to prime motor response during spatial conflict.
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Rounis, Elisabeth, Kielan Yarrow, and John C. Rothwell. "Effects of rTMS Conditioning over the Fronto-parietal Network on Motor versus Visual Attention." Journal of Cognitive Neuroscience 19, no. 3 (2007): 513–24. http://dx.doi.org/10.1162/jocn.2007.19.3.513.
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Many studies have shown that visuospatial orienting attention depends on a network of frontal and parietal areas in the right hemisphere. Rushworth et al. [Rushworth, M. F., Krams, M., & Passingham, R. E. The attentional role of the left parietal cortex: The distinct lateralization and localization of motor attention in the human brain. Journal of Cognitive Neuroscience, 13, 698–710, 2001] have recently provided evidence for a left-lateralized network of parietal areas involved in motor attention. Using two variants of a cued reaction time (RT) task, we set out to investigate whether high-frequency repetitive transcranial magnetic stimulation (rTMS; 5 Hz) delivered “off-line” in a virtual lesion paradigm over the right or left dorsolateral prefrontal cortex (DLPFC) or the posterior parietal cortex (PPC) would affect performance in a motor versus a visual attention task. Although rTMS over the DLPFC on either side did not affect RT performance on a spatial orienting task, it did lead to an increase in the RTs of invalidly cued trials in a motor attention task when delivered to the left DLPFC. The opposite effect was found when rTMS was delivered to the PPC: In this case, conditioning the right PPC led to increased RTs in invalidly cued trials located in the left hemispace, in the spatial orienting task. rTMS over the PPC on either side did not affect performance in the motor attention task. This double dissociation was evident in the first 10 min after rTMS conditioning. These results enhance our understanding of the networks associated with attention. They provide evidence of a role for the left DLPFC in the mechanisms of motor preparation, and confirm Mesulam's original proposal for a right PPC dominance in spatial attention [Mesulam, M. M. A cortical network for directed attention and unilateral neglect. Annals of Neurology, 10, 309–325, 1981].
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Öztekin, Ilke, Brian McElree, Bernhard P. Staresina, and Lila Davachi. "Working Memory Retrieval: Contributions of the Left Prefrontal Cortex, the Left Posterior Parietal Cortex, and the Hippocampus." Journal of Cognitive Neuroscience 21, no. 3 (2009): 581–93. http://dx.doi.org/10.1162/jocn.2008.21016.
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Functional magnetic resonance imaging was used to identify regions involved in working memory (WM) retrieval. Neural activation was examined in two WM tasks: an item recognition task, which can be mediated by a direct-access retrieval process, and a judgment of recency task that requires a serial search. Dissociations were found in the activation patterns in the hippocampus and in the left inferior frontal gyrus (LIFG) when the probe contained the most recently studied serial position (where a test probe can be matched to the contents of focal attention) compared to when it contained all other positions (where retrieval is required). The data implicate the hippocampus and the LIFG in retrieval from WM, complementing their established role in long-term memory. Results further suggest that the left posterior parietal cortex (LPPC) supports serial retrieval processes that are often required to recover temporal order information. Together, these data suggest that the LPPC, the LIFG, and the hippocampus collectively support WM retrieval. Critically, the reported findings support accounts that posit a distinction between representations maintained in and outside of focal attention, but are at odds with traditional dual-store models that assume distinct mechanisms for short- and long-term memory representations.
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Mevorach, Carmel, Glyn W. Humphreys, and Lilach Shalev. "Reflexive and Preparatory Selection and Suppression of Salient Information in the Right and Left Posterior Parietal Cortex." Journal of Cognitive Neuroscience 21, no. 6 (2009): 1204–14. http://dx.doi.org/10.1162/jocn.2009.21088.
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Attentional cues can trigger activity in the parietal cortex in anticipation of visual displays, and this activity may, in turn, induce changes in other areas of the visual cortex, hence, implementing attentional selection. In a recent TMS study [Mevorach, C., Humphreys, G. W., & Shalev, L. Opposite biases in salience-based selection for the left and right posterior parietal cortex. Nature Neuroscience, 9, 740–742, 2006b], it was shown that the posterior parietal cortex (PPC) can utilize the relative saliency (a nonspatial property) of a target and a distractor to bias visual selection. Furthermore, selection was lateralized so that the right PPC is engaged when salient information must be selected and the left PPC when the salient information must be ignored. However, it is not clear how the PPC implements these complementary forms of selection. Here we used on-line triple-pulse TMS over the right or left PPC prior to or after the onset of global/local displays. When delivered after the onset of the display, TMS to the right PPC disrupted the selection of the more salient aspect of the hierarchical letter. In contrast, left PPC TMS delivered prior to the onset of the stimulus disrupted responses to the lower saliency stimulus. These findings suggest that selection and suppression of saliency, rather than being “two sides of the same coin,” are fundamentally different processes. Selection of saliency seems to operate reflexively, whereas suppression of saliency relies on a preparatory phase that “sets up” the system in order to effectively ignore saliency.
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Lucerna, Alan, James Espinosa, Taimur Zaman, Risha Hertz, and Douglas Stranges. "Limb Pain as Unusual Presentation of a Parietal Intraparenchymal Bleeding Associated with Crack Cocaine Use: A Case Report." Case Reports in Neurological Medicine 2018 (May 31, 2018): 1–4. http://dx.doi.org/10.1155/2018/9598675.
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Limb pain as a presenting feature of an ischemic or hemorrhagic stroke is extremely rare. Here we present a case of a 65-year-old male with complaints of left arm pain and allodynia (specifically light touch to any part of the left arm produced significant discomfort) who was found to have a right parietal lobe intraparenchymal bleed after smoking crack cocaine. Acute central pain is mainly associated with parietal, thalamic, and brainstem lesions. It has been proposed that acute limb pain from a parietal lobe stroke is due to the disconnection of the parietal cortex from the thalamus secondary to the interruption of the pathways between the hemisphere and thalamus/basal ganglia.
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Bueti, Domenica, Bahador Bahrami, and Vincent Walsh. "Sensory and Association Cortex in Time Perception." Journal of Cognitive Neuroscience 20, no. 6 (2008): 1054–62. http://dx.doi.org/10.1162/jocn.2008.20060.
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The recent upsurge of interest in brain mechanisms of time perception is beginning to converge on some new starting points for investigating this long under studied aspect of our experience. In four experiments, we asked whether disruption of normal activity in human MT/V5 would interfere with temporal discrimination. Although clearly associated with both spatial and motion processing, MT/V5 has not yet been implicated in temporal processes. Following predictions from brain imaging studies that have shown the parietal cortex to be important in human time perception, we also asked whether disruption of either the left or right parietal cortex would interfere with time perception preferentially in the auditory or visual domain. The results show that the right posterior parietal cortex is important for timing of auditory and visual stimuli and that MT/V5 is necessary for timing only of visual events.
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Brass, Marcel, Markus Ullsperger, Thomas R. Knoesche, D. Yves von Cramon, and Natalie A. Phillips. "Who Comes First? The Role of the Prefrontal and Parietal Cortex in Cognitive Control." Journal of Cognitive Neuroscience 17, no. 9 (2005): 1367–75. http://dx.doi.org/10.1162/0898929054985400.
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Cognitive control processes enable us to adjust our behavior to changing environmental demands. Although neuropsychological studies suggest that the critical cortical region for cognitive control is the prefrontal cortex, neuro-imaging studies have emphasized the interplay of prefrontal and parietal cortices. This raises the fundamental question about the different contributions of prefrontal and parietal areas in cognitive control. It was assumed that the prefrontal cortex biases processing in posterior brain regions. This assumption leads to the hypothesis that neural activity in the prefrontal cortex should precede parietal activity in cognitive control. The present study tested this assumption by combining results from functional magnetic resonance imaging (fMRI) providing high spatial resolution and event-related potentials (ERPs) to gain high temporal resolution. We collected ERP data using a modified task-switching paradigm. In this paradigm, a situation where the same task was indicated by two different cues was compared with a situation where two cues indicated different tasks. Only the latter condition required updating of the task set. Task-set updating was associated with a midline negative ERP deflection peaking around 470 msec. We placed dipoles in regions activated in a previous fMRI study that used the same paradigm (left inferior frontal junction, right inferior frontal gyrus, right parietal cortex) and fitted their directions and magnitudes to the ERP effect. The frontal dipoles contributed to the ERP effect earlier than the parietal dipole, providing support for the view that the prefrontal cortex is involved in updating of general task representations and biases relevant stimulus-response associations in the parietal cortex.
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Stockert, Anika, Max Wawrzyniak, Julian Klingbeil, et al. "Dynamics of language reorganization after left temporo-parietal and frontal stroke." Brain 143, no. 3 (2020): 844–61. http://dx.doi.org/10.1093/brain/awaa023.
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Abstract The loss and recovery of language functions are still incompletely understood. This longitudinal functional MRI study investigated the neural mechanisms underlying language recovery in patients with post-stroke aphasia putting particular emphasis on the impact of lesion site. To identify patterns of language-related activation, an auditory functional MRI sentence comprehension paradigm was administered to patients with circumscribed lesions of either left frontal (n = 17) or temporo-parietal (n = 17) cortex. Patients were examined repeatedly during the acute (≤1 week, t1), subacute (1–2 weeks, t2) and chronic phase (&gt;6 months, t3) post-stroke; healthy age-matched control subjects (n = 17) were tested once. The separation into two patient groups with circumscribed lesions allowed for a direct comparison of the contributions of distinct lesion-dependent network components to language reorganization between both groups. We hypothesized that activation of left hemisphere spared and perilesional cortex as well as lesion-homologue cortex in the right hemisphere varies between patient groups and across time. In addition, we expected that domain-general networks serving cognitive control independently contribute to language recovery. First, we found a global network disturbance in the acute phase that is characterized by reduced functional MRI language activation including areas distant to the lesion (i.e. diaschisis) and subsequent subacute network reactivation (i.e. resolution of diaschisis). These phenomena were driven by temporo-parietal lesions. Second, we identified a lesion-independent sequential activation pattern with increased activity of perilesional cortex and bilateral domain-general networks in the subacute phase followed by reorganization of left temporal language areas in the chronic phase. Third, we observed involvement of lesion-homologue cortex only in patients with frontal but not temporo-parietal lesions. Fourth, irrespective of lesion location, language reorganization predominantly occurred in pre-existing networks showing comparable activation in healthy controls. Finally, we detected different relationships of performance and activation in language and domain-general networks demonstrating the functional relevance for language recovery. Our findings highlight that the dynamics of language reorganization clearly depend on lesion location and hence open new perspectives for neurobiologically motivated strategies of language rehabilitation, such as individually-tailored targeted application of neuro-stimulation.
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Shulman, Gordon L., Julie A. Fiez, Maurizio Corbetta, et al. "Common Blood Flow Changes across Visual Tasks: II. Decreases in Cerebral Cortex." Journal of Cognitive Neuroscience 9, no. 5 (1997): 648–63. http://dx.doi.org/10.1162/jocn.1997.9.5.648.
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Nine previous positron emission tomography (PET) studies of human visual information processing were reanalyzed to determine the consistency across experiments of blood flow decreases during active tasks relative to passive viewing of the same stimulus array. Areas showing consistent decreases during active tasks included posterior cingulate/precuneous (Brodmann area, BA 31/7), left (BAS 40 and 39/19) and right (BA 40) inferior parietal cortex, left dorsolateral frontal cortex (BA S), left lateral inferior frontal cortex (BA 10/47), left inferior temporal gyrus @A 20), a strip of medial frontal regions running along a dorsal-ventral axis (BAs 8, 9, 10, and 32), and the right amygdala. Experiments involving language-related processes tended to show larger decreases than nonlanguage experiments. This trend mainly reflected blood flow increases at certain areas in the passive conditions of the language experiments (relative to a fixation control in which no task stimulus was present) and slight blood flow decreases in the passive conditions of the nonlanguage experiments. When the active tasks were referenced to the fixation condition, the overall size of blood flow decreases in language and nonlanguage tasks were the same, but differences were found across cortical areas. Decreases were more pronounced in the posterior cingulate/precuneous (BAS 31/7) and right inferior parietal cortex (BA 40) during language-related tasks and more pronounced in left inferior frontal cortex (BA 10/47) during nonlanguage tasks. Blood flow decreases did not generally show significant differences across the active task states within an experiment, but a verb-generation task produced larger decreases than a read task in right and left inferior parietal lobe (BA 40) and the posterior cingulate/precuneous (BA 31/7), while the read task produced larger decreases in left lateral inferior frontal cortex (BA 10/47). These effects mirrored those found between experiments in the language-nonlanguage comparison. Consistent active minus passive decreases may reflect decreased activity caused by active task processes that generalize over tasks or increased activity caused by passive task processes that are suspended during the active tasks. Increased activity during the passive condition might reflect ongoing processes, such as unconstrained verbally mediated thoughts and monitoring of the external environment, body, and emotional state.
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Thimm, M., G. R. Fink, and W. Sturm. "Neural correlates of recovery from acute hemispatial neglect." Restorative Neurology and Neuroscience 26, no. 6 (2008): 481–92. https://doi.org/10.3233/rnn-2008-00434.
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Purpose: To investigate the neural correlates associated with recovery from acute spatial neglect resulting from right hemispheric stroke. Methods: Four neglect patients were investigated both behaviourally and by fMRI at an acute (18 ± 5 days) and at a chronic stage (123 ± 18 days) post stroke. Results: At the second assessment all patients showed substantial behavioural improvements. These were associated with an increase of neural activity in the right middle frontal gyrus, right inferior parietal cortex, right inferior temporal gyrus/fusiform gyrus, left superior temporal gyrus/angular gyrus and left anterior cingulate gyrus. Decreased neural activity at the second assessment was found in the right parahippocampal gyrus and left fusiform gyrus. Conclusions: The pattern of neural reorganisation comprises areas of a right hemisphere fronto-parietal attentional network and corresponding left hemisphere areas suggesting a compensatory recruitment of analogous contralesional areas. Interestingly, a more complex pattern of neural changes was observed in the fusiform gyri which have previously been implicated in lateralised directed spatial attention. There was an increase in the right hemisphere and a decrease in the left hemisphere. This pattern of recovery is reminiscent of a "push-pull" pattern previously described for the dorsal parietal cortex by Corbetta et al. (2005) in the recovery from spatial neglect.
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PERES, JULIO F. P., ANDREW B. NEWBERG, JULIANE P. MERCANTE, et al. "Cerebral blood flow changes during retrieval of traumatic memories before and after psychotherapy: a SPECT study." Psychological Medicine 37, no. 10 (2007): 1481–91. http://dx.doi.org/10.1017/s003329170700997x.
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ABSTRACTBackgroundTraumatic memory is a key symptom in psychological trauma victims and may remain vivid for several years. Psychotherapy has shown that neither the psychopathological signs of trauma nor the expression of traumatic memories are static over time. However, few studies have investigated the neural substrates of psychotherapy-related symptom changes.MethodWe studied 16 subthreshold post-traumatic stress disorder (PTSD) subjects by using a script-driven symptom provocation paradigm adapted for single photon emission computed tomography (SPECT) that was read aloud during traumatic memory retrieval both before and after exposure-based and cognitive restructuring therapy. Their neural activity levels were compared with a control group comprising 11 waiting-list subthreshold PTSD patients, who were age- and profile-matched with the psychotherapy group.ResultsSignificantly higher activity was observed in the parietal lobes, left hippocampus, thalamus and left prefrontal cortex during memory retrieval after psychotherapy. Positive correlations were found between activity changes in the left prefrontal cortex and left thalamus, and also between the left prefrontal cortex and left parietal lobe.ConclusionsNeural mechanisms involved in subthreshold PTSD may share neural similarities with those underlying the fragmented and non-verbal nature of traumatic memories in full PTSD. Moreover, psychotherapy may influence the development of a narrative pattern overlaying the declarative memory neural substrates.
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Zacks, Jeffrey M., Jean M. Vettel, and Pascale Michelon. "Imagined Viewer and Object Rotations Dissociated with Event-Related fMRI." Journal of Cognitive Neuroscience 15, no. 7 (2003): 1002–18. http://dx.doi.org/10.1162/089892903770007399.
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Human spatial reasoning may depend in part on two dissociable types of mental image transformations: objectbased transformations, in which an object is imagined to move in space relative to the viewer and the environment, and perspective transformations, in which the viewer imagines the scene from a different vantage point. This study measured local brain activity with event-related fMRI while participants were instructed to either imagine an array of objects rotating (an object-based transformation) or imagine themselves rotating around the array (a perspective transformation). Object-based transformations led to selective increases in right parietal cortex and decreases in left parietal cortex, whereas perspective transformations led to selective increases in left temporal cortex. These results argue against the view that mental image transformations are performed by a unitary neural processing system, and they suggest that different overlapping systems are engaged for different image transformations.
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Lange, Floris P. de, Peter Hagoort, and Ivan Toni. "Neural Topography and Content of Movement Representations." Journal of Cognitive Neuroscience 17, no. 1 (2005): 97–112. http://dx.doi.org/10.1162/0898929052880039.
Full textAbstract:
We have used implicit motor imagery to investigate the neural correlates of motor planning independently from actual movements. Subjects were presented with drawings of left or right hands and asked to judge the hand laterality, regardless of the stimulus rotation from its upright orientation. We paired this task with a visual imagery control task, in which subjects were presented with typographical characters and asked to report whether they saw a canonical letter or its mirror image, regardless of its rotation. We measured neurovascular activity with fast event-related fMRI, distinguishing responses parametrically related to motor imagery from responses evoked by visual imagery and other task-related phenomena. By quantifying behavioral and neurovascular correlates of imagery on a trial-by-trial basis, we could discriminate between stimulus-related, mental rotation-related, and response-related neural activity. We found that specific portions of the posterior parietal and precentral cortex increased their activity as a function of mental rotation only during the motor imagery task. Within these regions, the parietal cortex was visually responsive, whereas the dorsal precentral cortex was not. Response- but not rotation-related activity was found around the left central sulcus (putative primary motor cortex) during both imagery tasks. Our study provides novel evidence on the topography and content of movement representations in the human brain. During intended action, the posterior parietal cortex combines somatosensory and visuomotor information, whereas the dorsal premotor cortex generates the actual motor plan, and the primary motor cortex deals with movement execution. We discuss the relevance of these results in the context of current models of action planning.
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Kansaku, Kenji. "Spatio-temporal updating in the posterior parietal cortex." Seeing and Perceiving 25 (2012): 12. http://dx.doi.org/10.1163/187847612x646352.
Full textAbstract:
Adopting an unusual posture can sometimes give rise to paradoxical experiences. For example, the subjective ordering of successive unseen tactile stimuli delivered to the two arms can be affected when people cross them. A growing body of evidence highlights the role played by the parietal cortex in spatio-temporal information processing when sensory stimuli are delivered to the body or when actions are executed; however, little is known about the neural basis of such paradoxical feelings. We demonstrate increased fMRI activation in the left posterior parietal cortex when human participants adopted a crossed hands posture with their eyes closed. When participants performed tactile temporal order judgments (TOJs), we observed a positive association between activity in this area and the degree of reversal in TOJs resulting from crossing arms. The strongest positive association was observed in the left intraparietal sulcus (IPS) (Wada et al., 2011). We then examined connectivity of the IPS to determine the functional anatomy of the arm crossing effect, as well as connectivity using a seed region in the posterior cingulate cortex to evaluate default mode network (DMN) for comparison. The regions showing connectivity with the IPS overlapped with regions within the DMN but the IPS also showed connectivity with other brain areas within the frontoparietal control network (Ora et al., 2012). The IPS, which can be considered a gateway connecting the DMN to the frontoparietal control network, may therefore be critically involved in monitoring limb position and in spatio-temporal binding when serial events are delivered to the limbs.
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Cappelletti, Marinella, Hwee Ling Lee, Elliot D. Freeman, and Cathy J. Price. "The Role of Right and Left Parietal Lobes in the Conceptual Processing of Numbers." Journal of Cognitive Neuroscience 22, no. 2 (2010): 331–46. http://dx.doi.org/10.1162/jocn.2009.21246.
Full textAbstract:
Neuropsychological and functional imaging studies have associated the conceptual processing of numbers with bilateral parietal regions (including intraparietal sulcus). However, the processes driving these effects remain unclear because both left and right posterior parietal regions are activated by many other conceptual, perceptual, attention, and response-selection processes. To dissociate parietal activation that is number-selective from parietal activation related to other stimulus or response-selection processes, we used fMRI to compare numbers and object names during exactly the same conceptual and perceptual tasks while factoring out activations correlating with response times. We found that right parietal activation was higher for conceptual decisions on numbers relative to the same tasks on object names, even when response time effects were fully factored out. In contrast, left parietal activation for numbers was equally involved in conceptual processing of object names. We suggest that left parietal activation for numbers reflects a range of processes, including the retrieval of learnt facts that are also involved in conceptual decisions on object names. In contrast, number selectivity in right parietal cortex reflects processes that are more involved in conceptual decisions on numbers than object names. Our results generate a new set of hypotheses that have implications for the design of future behavioral and functional imaging studies of patients with left and right parietal damage.
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Hu, Haimeng, Yining Lyu, Shihong Li, et al. "Aberrant Resting-State Functional Connectivity of the Dorsal Attention Network in Tinnitus." Neural Plasticity 2021 (December 31, 2021): 1–9. http://dx.doi.org/10.1155/2021/2804533.
Full textAbstract:
Previous functional magnetic resonance imaging (fMRI) analyses have shown that the dorsal attention network (DAN) is involved in the pathophysiological changes of tinnitus, but few relevant studies have been conducted, and the conclusions to date are not uniform. The purpose of this research was to test whether there is a change in intrinsic functional connectivity (FC) patterns between the DAN and other brain regions in tinnitus patients. Thirty-one patients with persistent tinnitus and thirty-three healthy controls were enrolled in this study. A group independent component analysis (ICA), degree centrality (DC) analysis, and seed-based FC analysis were conducted. In the group ICA, the tinnitus patients showed increased connectivity in the left superior parietal gyrus in the DAN compared to the healthy controls. Compared with the healthy controls, the tinnitus patients showed increased DC in the left inferior parietal gyrus and decreased DC in the left precuneus within the DAN. The clusters within the DAN with significant differences in the ICA or DC analysis between the tinnitus patients and the healthy controls were selected as regions of interest (ROIs) for seeds. The tinnitus patients exhibited significantly increased FC from the left superior parietal gyrus to several brain regions, including the left inferior parietal gyrus, the left superior marginal gyrus, and the right superior frontal gyrus, and decreased FC to the right anterior cingulate cortex. The tinnitus patients exhibited decreased FC from the left precuneus to the left inferior occipital gyrus, left calcarine cortex, and left superior frontal gyrus compared with the healthy controls. The findings of this study show that compared with healthy controls, tinnitus patients have altered functional connections not only within the DAN but also between the DAN and other brain regions. These results suggest that it may be possible to improve the disturbance and influence of tinnitus by regulating the DAN.
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Ro, Tony, Ruth Wallace, Judith Hagedorn, Alessandro Farné, and Elizabeth Pienkos. "Visual Enhancing of Tactile Perception in the Posterior Parietal Cortex." Journal of Cognitive Neuroscience 16, no. 1 (2004): 24–30. http://dx.doi.org/10.1162/089892904322755520.
Full textAbstract:
Rice University The visual modality typically dominates over our other senses. Here we show that after inducing an extreme conflict in the left hand between vision of touch (present) and the feeling of touch (absent), sensitivity to touch increases for several minutes after the conflict. Transcranial magnetic stimulation of the posterior parietal cortex after this conflict not only eliminated the enduring visual enhancement of touch, but also impaired normal tactile perception. This latter finding demonstrates a direct role of the parietal lobe in modulating tactile perception as a result of the conflict between these senses. These results provide evidence for visual-to-tactile perceptual modulation and demonstrate effects of illusory vision of touch on touch perception through a long-lasting modulatory process in the posterior parietal cortex.
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LOMBER, STEPHEN G., and BERTRAM R. PAYNE. "Contributions of cat posterior parietal cortex to visuospatial discrimination." Visual Neuroscience 17, no. 5 (2000): 701–9. http://dx.doi.org/10.1017/s0952523800175042.
Full textAbstract:
The purpose of the present study was to examine the contributions made by cat posterior parietal cortex to the analyses of the relative position of objects in visual space. Two cats were trained on a landmark task in which they learned to report the position of a landmark object relative to a right or left food-reward chamber. Subsequently, three pairs of cooling loops were implanted bilaterally in contact with visuoparietal cortices forming the crown of the middle suprasylvian gyrus (MSg; architectonic area 7) and the banks of the posterior-middle suprasylvian sulcus (pMS sulcal cortex) and in contact with the ventral-posterior suprasylvian (vPS) region of visuotemporal cortex. Bilateral deactivation of pMS sulcal cortex resulted in a profound impairment for all six tested positions of the landmark, yet bilateral deactivation of neither area 7 nor vPS cortex yielded any deficits. In control tasks (visual orienting and object discrimination), there was no evidence for any degree of attentional blindness or impairment of form discrimination during bilateral deactivation of pMS cortex. Therefore, we conclude that bilateral cooling of pMS cortex, but neither area 7 nor vPS cortex, induces a specific deficit in spatial localization as examined with the landmark task. These observations have significant bearing on our understanding of visuospatial processing in cat, monkey, and human cortices.