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Ahmed, Zaghloul, and Andrzej Wieraszko. "Trans-spinal direct current enhances corticospinal output and stimulation-evoked release of glutamate analog, D-2,3-3H-aspartic acid." Journal of Applied Physiology 112, no. 9 (2012): 1576–92. http://dx.doi.org/10.1152/japplphysiol.00967.2011.
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Trans-spinal direct current (tsDC) stimulation is a modulator of spinal excitability and can influence cortically elicited muscle contraction in a polarity-dependent fashion. When combined with low-frequency repetitive cortical stimulation, cathodal tsDC [tsDC(−)] produces a long-term facilitation of cortically elicited muscle actions. We investigated the ability of this combined stimulation paradigm to facilitate cortically elicited muscle actions in spinal cord-injured and noninjured animals. The effect of tsDC—applied alone or in combination with repetitive spinal stimulation (rSS) on the release of the glutamate analog, D-2,3-3H-aspartate (D-Asp), from spinal cord preparations in vitro—was also tested. In noninjured animals, tsDC (−2 mA) reproducibly potentiated cortically elicited contractions of contralateral and ipsilateral muscles tested at various levels of baseline muscle contraction forces. Cortically elicited muscle responses in animals with contusive and hemisectioned spinal cord injuries (SCIs) were similarly potentiated. The combined paradigm of stimulation caused long-lasting potentiation of cortically elicited bilateral muscle contraction in injured and noninjured animals. Additional analysis suggests that at higher baseline forces, tsDC(−) application does not increase the rising slope of the muscle contraction but causes repeated firing of the same motor units. Both cathodal and anodal stimulations induced a significant increase of D-Asp release in vitro. The effect of the combined paradigm of stimulation (tsDC and rSS) on the concentration of extracellular D-Asp was polarity dependent. These results indicate that tsDC can powerfully modulate the responsiveness of spinal cord neurons. The results obtained from the in vitro preparation suggest that the changes in neuronal excitability were correlated with an increased concentration of extracellular glutamate. The combined paradigm of stimulation, used in our experiments, could be noninvasively applied to restore motor control in humans with SCI.
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Foster, Brett L., and Josef Parvizi. "Direct cortical stimulation of human posteromedial cortex." Neurology 88, no. 7 (2017): 685–91. http://dx.doi.org/10.1212/wnl.0000000000003607.
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Background:The posteromedial cortex (PMC) is a collective term for an anatomically heterogeneous area of the brain constituting a core node of the human default mode network (DMN), which is engaged during internally focused subjective cognition such as autobiographical memory.Methods:We explored the effects of causal perturbations of PMC with direct electric brain stimulation (EBS) during presurgical epilepsy monitoring with intracranial EEG electrodes.Results:Data were collected from 885 stimulations in 25 patients implanted with intracranial electrodes across the PMC. While EBS of regions immediately dorsal or ventral to the PMC reliably produced somatomotor or visual effects, respectively, we found no observable behavioral or subjectively reported effects when sites within the boundaries of PMC were electrically perturbed. In each patient, null effects of PMC stimulation were observed for sites in which intracranial recordings had clearly demonstrated electrophysiologic responses during autobiographical recall.Conclusions:Direct electric modulation of the human PMC produced null effects when standard functional mapping methods were used. More sophisticated stimulation paradigms (e.g., EBS during experimental cognitive tests) will be required for testing the causal contribution of PMC to human cognition and subjective experience. Nonetheless, our findings suggest that some extant theories of PMC and DMN contribution to human awareness and subjective conscious states require cautious re-examination.
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Lee, Hongju, Juyeon Lee, Dahee Jung, Harim Oh, Hwakyoung Shin, and Byungtae Choi. "Neuroprotection of Transcranial Cortical and Peripheral Somatosensory Electrical Stimulation by Modulating a Common Neuronal Death Pathway in Mice with Ischemic Stroke." International Journal of Molecular Sciences 25, no. 14 (2024): 7546. http://dx.doi.org/10.3390/ijms25147546.
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Therapeutic electrical stimulation, such as transcranial cortical stimulation and peripheral somatosensory stimulation, is used to improve motor function in patients with stroke. We hypothesized that these stimulations exert neuroprotective effects during the subacute phase of ischemic stroke by regulating novel common signaling pathways. Male C57BL/6J mouse models of ischemic stroke were treated with high-definition (HD)-transcranial alternating current stimulation (tACS; 20 Hz, 89.1 A/mm2), HD-transcranial direct current stimulation (tDCS; intensity, 55 A/mm2; charge density, 66,000 C/m2), or electroacupuncture (EA, 2 Hz, 1 mA) in the early stages of stroke. The therapeutic effects were assessed using behavioral motor function tests. The underlying mechanisms were determined using transcriptomic and other biomedical analyses. All therapeutic electrical tools alleviated the motor dysfunction caused by ischemic stroke insults. We focused on electrically stimulating common genes involved in apoptosis and cell death using transcriptome analysis and chose 11 of the most potent targets (Trem2, S100a9, Lgals3, Tlr4, Myd88, NF-kB, STAT1, IL-6, IL-1β, TNF-α, and Iba1). Subsequent investigations revealed that electrical stimulation modulated inflammatory cytokines, including IL-1β and TNF-α, by regulating STAT1 and NF-kB activation, especially in amoeboid microglia; moreover, electrical stimulation enhanced neuronal survival by activating neurotrophic factors, including BDNF and FGF9. Therapeutic electrical stimulation applied to the transcranial cortical- or periphery-nerve level to promote functional recovery may improve neuroprotection by modulating a common neuronal death pathway and upregulating neurotrophic factors. Therefore, combining transcranial cortical and peripheral somatosensory stimulation may exert a synergistic neuroprotective effect, further enhancing the beneficial effects on motor deficits in patients with ischemic stroke.
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Adeel, Muhammad, Chun-Ching Chen, Bor-Shing Lin, et al. "Safety of Special Waveform of Transcranial Electrical Stimulation (TES): In Vivo Assessment." International Journal of Molecular Sciences 23, no. 12 (2022): 6850. http://dx.doi.org/10.3390/ijms23126850.
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Intermittent theta burst (iTBS) powered by direct current stimulation (DCS) can safely be applied transcranially to induce neuroplasticity in the human and animal brain cortex. tDCS-iTBS is a special waveform that is used by very few studies, and its safety needs to be confirmed. Therefore, we aimed to evaluate the safety of tDCS-iTBS in an animal model after brain stimulations for 1 h and 4 weeks. Thirty-one Sprague Dawley rats were divided into two groups: (1) short-term stimulation for 1 h/session (sham, low, and high) and (2) long-term for 30 min, 3 sessions/week for 4 weeks (sham and high). The anodal stimulation applied over the primary motor cortex ranged from 2.5 to 4.5 mA/cm2. The brain biomarkers and scalp tissues were assessed using ELISA and histological analysis (H&E staining) after stimulations. The caspase-3 activity, cortical myelin basic protein (MBP) expression, and cortical interleukin (IL-6) levels increased slightly in both groups compared to sham. The serum MBP, cortical neuron-specific enolase (NSE), and serum IL-6 slightly changed from sham after stimulations. There was no obvious edema or cell necrosis seen in cortical histology after the intervention. The short- and long-term stimulations did not induce significant adverse effects on brain and scalp tissues upon assessing biomarkers and conducting histological analysis.
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Yaksh, Tony L., Jia-Yi Wang, V. L. W. Go, and Gail J. Harty. "Cortical Vasodilatation Produced by Vasoactive Intestinal Polypeptide (VIP) and by Physiological Stimuli in the Cat." Journal of Cerebral Blood Flow & Metabolism 7, no. 3 (1987): 315–26. http://dx.doi.org/10.1038/jcbfm.1987.69.
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In chloralose-urethanized cats, vasoactive intestinal peptide (VIP), applied by superfusion in steady-state concentration (10−10–10−6 M) onto cortical vessels in situ resulted in a rapid concentration-dependent vasodilatation in vessels that were mildly constricted by prostaglandin F2α (PGF2α) (5 × 10−5 M) or hypocarbia (PaCO2 = 26). The maximum dilatation produced by VIP (10−6 M) was about 60% over baseline in pial arteries and 40% in pial veins. Blockade of local neuronal activity with tetrodotoxin (TTX) (10−5 M) had no effect on the VIP-evoked dilation of pial vessels. Activation of the cortex by either direct electrical stimulation or indirectly by stimulation of the mesencephalic reticular formation (MRF) resulted in a rapid dilatation of pial arterioles and venules. The vasodilatory effects of VIP and of cortical activation via direct cortical stimulation were not blocked by phentolamine (10−4 M), propranolol (10−4 M), atropine (10−4 M), or naloxone (10−4 M), indicating that the stimulated vasodilatation was not mediated by adrenergic, cholinergic, or opiate receptors. The dilatory effects of MRF, but not direct cortical stimulation, were not blocked by TTX. VIP antiserum (1:25) preincubated in cortical cups had no effect on resting vessel diameter, but resulted in a significant, though subtotal, reduction in the vasodilatation elicited by direct cortical and MRF stimulation. Normal rabbit sera or VIP antiserum preincubated with saturating amounts of VIP were ineffective. In similar experiments, pial arteriolar and venular dilation evoked by hypercarbia was not attenuated by cortically applied VIP antisera. These observations suggest that pial dilation evoked by local increases in neuronal activity may be mediated in part by the local release of VIP from intrinsic neurons. Such a substrate would define a close obligatory coupling between local neuronal activation and local perfusion, such that nutritive flow could be enhanced prior to the onset of any metabolic deficit.
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Huang, Yuhao (Danny), Sydney Cash, Corey Keller, and Angelique Paulk. "243 Intracranial Theta-burst Stimulation Modulates Cortical Excitability in a Dose and Location-dependent Fashion." Neurosurgery 70, Supplement_1 (2024): 67. http://dx.doi.org/10.1227/neu.0000000000002809_243.
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INTRODUCTION: Direct electrical stimulation is a powerful therapeutic approach to treating a wide range of brain disorders. In particular, theta-burst stimulation (TBS) which delivers electrical pulses in rhythmic bursts of 3-8 Hz to mimic endogenous brain rhythms, has been increasingly used to improve cognitive processes and relieve symptoms of depression. However, how TBS alters underlying neural activity is poorly understood. METHODS: In nine neurosurgical epilepsy subjects undergoing intracranial monitoring, we applied direct cortical TBS at varying stimulation amplitudes and locations (prefrontal, temporal, parietal). We obtained single-pulse corticocortical evoked potentials (CCEPs) prior to stimulation to map functional connectivity. Intracranial EEG (iEEG) was recorded from non-stimulated electrodes before, during and after TBS. RESULTS: We found that TBS evoked consistent responses after each burst. These responses were observed in regions with high amplitude CCEPs and resting spontaneous delta (1-4 Hz) phase-locking to the stimulation site, consistent with our hypothesis that the underlying functional brain architecture guides information flow after stimulation. Furthermore, we observed changes in cortical excitability over time as measured by changes in amplitude of the TBS evoked responses both within stimulation burst trains and across burst trains. The degree of change in cortical excitability was modulated by anatomical location, proximity of the stimulating electrode to white matter, and current amplitude. CONCLUSIONS: These results indicate that direct cortical TBS produces neural effects that can be measured over time and correlate with baseline biophysical parameters. Thus, personalizing stimulation parameters might be critical to predictably maximize our ability to alter disease-relevant brain networks.
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Moliadze, Vera, Georg Fritzsche, and Andrea Antal. "Comparing the Efficacy of Excitatory Transcranial Stimulation Methods Measuring Motor Evoked Potentials." Neural Plasticity 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/837141.
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The common aim of transcranial stimulation methods is the induction or alterations of cortical excitability in a controlled way. Significant effects of each individual stimulation method have been published; however, conclusive direct comparisons of many of these methods are rare. The aim of the present study was to compare the efficacy of three widely applied stimulation methods inducing excitability enhancement in the motor cortex: 1 mA anodal transcranial direct current stimulation (atDCS), intermittent theta burst stimulation (iTBS), and 1 mA transcranial random noise stimulation (tRNS) within one subject group. The effect of each stimulation condition was quantified by evaluating motor-evoked-potential amplitudes (MEPs) in a fixed time sequence after stimulation. The analyses confirmed a significant enhancement of the M1 excitability caused by all three types of active stimulations compared to sham stimulation. There was no significant difference between the types of active stimulations, although the time course of the excitatory effects slightly differed. Among the stimulation methods, tRNS resulted in the strongest and atDCS significantly longest MEP increase compared to sham. Different time courses of the applied stimulation methods suggest different underlying mechanisms of action. Better understanding may be useful for better targeting of different transcranial stimulation techniques.
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Ahmed, Zaghloul. "Trans-spinal direct current stimulation modulates motor cortex-induced muscle contraction in mice." Journal of Applied Physiology 110, no. 5 (2011): 1414–24. http://dx.doi.org/10.1152/japplphysiol.01390.2010.
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The present study investigated the effect of trans-spinal direct current (tsDC) on the firing rate, pattern, and amplitude of spontaneous activity of the tibial nerve and on the magnitude of cortically elicited triceps surae (TS) muscle contractions. The effect of combined tsDC and repetitive cortical electrical stimulation (rCES) on the amplitude of cortically elicited TS twitches was also investigated. Stimulation was applied by two disk electrodes (0.79 cm2): one was located subcutaneously over the vertebral column (T10–L1) and was used to deliver anodal DC (a-tsDC) or cathodal DC (c-tsDC) (density range: ± 0.64 to ± 38.2 A/m2), whereas the other was located subcutaneously on the lateral aspect of the abdomen and served as a reference. While the application of a-tsDC significantly increased the spike frequency and amplitude of spontaneous discharges compared with c-tsDC, c-tsDC made the spontaneous discharges more rhythmic. Cortically elicited TS twitches were depressed during a-tsDC and potentiated after termination. Conversely, cortically elicited TS twitches were enhanced during c-tsDC and depressed after termination. While combined a-tsDC and rCES produced similar effects as a-tsDC alone, combined c-tsDC and rCES showed the greatest increase in cortically elicited TS twitches. tsDC appears to be a powerful neurostimulation tool that can differentially modulate spinal cord excitability and corticospinal transmission.
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Ip, Emily Y., Elisa Roncati Zanier, Amy H. Moore, Stefan M. Lee, and David A. Hovda. "Metabolic, Neurochemical, and Histologic Responses to Vibrissa Motor Cortex Stimulation after Traumatic Brain Injury." Journal of Cerebral Blood Flow & Metabolism 23, no. 8 (2003): 900–910. http://dx.doi.org/10.1097/01.wcb.0000076702.71231.f2.
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During the prolonged metabolic depression after traumatic brain injury (TBI), neurons are less able to respond metabolically to peripheral stimulation. Because this decreased responsiveness has been attributed to circuit dysfunction, the present study examined the metabolic, neurochemical, and histologic responses to direct cortical stimulation after lateral fluid percussion injury (LFPI). This study addressed three specific hypotheses: that neurons, if activated after LFPI, will increase their utilization of glucose even during a period of posttraumatic metabolic depression; that this secondary activation results in an increase in the production of lactate and a depletion of extracellular glucose; and that because cells are known to be in a state of energy crisis after traumatic brain injury, additional energy demands resulting from activation can result in their death. The results indicate that stimulating to levels eliciting a vibrissa twitch resulted in an increase in the cerebral metabolic rate for glucose (CMRglc; μmol·100 g−1·min−1) of 34% to 61% in the sham-operated, 1-hour LFPI, and 7-day LFPI groups. However, in the 1-day LFPI group, stimulation induced a 161% increase in CMRglc and a 35% decrease in metabolic activation volume. Extracellular lactate concentrations during stimulation significantly increased from 23% in the sham-injured group to 55% to 63% in the 1-day and 7-day LFPI groups. Extracellular glucose concentrations during stimulation remained unchanged in the sham-injured and 7-day LFPI groups, but decreased 17% in the 1-day LFPI group. The extent of cortical degeneration around the stimulating electrode in the 1-day LFPI group nearly doubled when compared with controls. These results indicate that at 1 day after LFPI, the cortex can respond to stimulation with an increase in anaerobic glycolysis; however, this metabolic response to levels eliciting a vibrissa response via direct cortical stimulation appears to constitute a secondary injury in the TBI brain.
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Qi, Xiaofei, Kexin Lyu, Long Meng, et al. "Low-Intensity Ultrasound Causes Direct Excitation of Auditory Cortical Neurons." Neural Plasticity 2021 (April 4, 2021): 1–10. http://dx.doi.org/10.1155/2021/8855055.
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Cochlear implantation is the first-line treatment for severe and profound hearing loss in children and adults. However, deaf patients with cochlear malformations or with cochlear nerve deficiencies are ineligible for cochlear implants. Meanwhile, the limited spatial selectivity and high risk of invasive craniotomy restrict the wide application of auditory brainstem implants. A noninvasive alternative strategy for safe and effective neuronal stimulation is urgently needed to address this issue. Because of its advantage in neural modulation over electrical stimulation, low-intensity ultrasound (US) is considered a safe modality for eliciting neural activity in the central auditory system. Although the neural modulation ability of low-intensity US has been demonstrated in the human primary somatosensory cortex and primary visual cortex, whether low-intensity US can directly activate auditory cortical neurons is still a topic of debate. To clarify the direct effects on auditory neurons, in the present study, we employed low-intensity US to stimulate auditory cortical neurons in vitro. Our data show that both low-frequency (0.8 MHz) and high-frequency (>27 MHz) US stimulation can elicit the inward current and action potentials in cultured neurons. c-Fos staining results indicate that low-intensity US is efficient for stimulating most neurons. Our study suggests that low-intensity US can excite auditory cortical neurons directly, implying that US-induced neural modulation can be a potential approach for activating the auditory cortex of deaf patients.
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Saleem, Yusra, Komal ., and Stephen Riaz. "Transcranial Direct Current Stimulation (TDCS)." International Journal of Endorsing Health Science Research (IJEHSR) 10, no. 4 (2022): 441–45. http://dx.doi.org/10.29052/ijehsr.v10.i4.2022.441-445.
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Transcranial direct current stimulation (TDCS) is a neuromodulatory device that is used for its ability to enhance cognitive and behavioral performance. Human studies suggest that TDCS modulates cortical excitability during stimulation by nonsynaptic changes of the cells, along with evidence that the after-effects of TDCS are driven by synaptic modification. TDCS represents a potential intervention to enhance cognition across clinical populations, including mild cognitive impairment among psychological and neurological disorders. Studies suggest that TDCS might be helpful in treating depression with appropriate current, size of electrodes, and employment of montages. TDCS opens a new perspective in treating major depressive disorder (MDD) because of its ability to modulate cortical excitability and induce long-lasting effects.
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Madsen, Jesper Guldsmed, Jakob Appel Østergaard, Henning Andersen, and Michael Pedersen. "Attenuation of Cortically Evoked Motor-Neuron Potential in Streptozotocin-Induced Diabetic Rats: A Study about the Effect of Diabetes upon Cortical-Initiated Movement." BioMed Research International 2020 (February 26, 2020): 1–5. http://dx.doi.org/10.1155/2020/1942534.
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Aims/Hypothesis. The complications affecting the peripheral nervous system, associated with diabetes mellitus, have been the focus of considerable research. Comparably less research has focused upon the effect of diabetes upon the central nervous system. In this study, we investigate the effect of diabetes upon motor-neuron potentials evoked in the motor cortex of streptozotocin diabetic rats. Methods. In this study, we investigated the cortical-evoked motor-neuron potentials in streptozotocin-induced diabetic rats. Cortical potentials were evoked using direct current stimulation to the motor cortex, and the resulting evoked potentials were recorded in the sciatic nerve. As voluntary movement consists of repeated activation of muscles, repeated stimulation trials were used to determine the effect of diabetes upon the animals’ ability to recuperate between stimulations. Results. Our findings showed that diabetes severely decreased the amplitude of cortical-evoked potentials and compromised the recuperation of motor neurons between activation. Conclusion/Interpretation. The reduced amplitude and weakened recuperation of diabetic motor neurons potentially may contribute to impaired transmission in motor pathways and thereby motor dysfunction.
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Katakura, N., and S. H. Chandler. "An iontophoretic analysis of the pharmacologic mechanisms responsible for trigeminal motoneuronal discharge during masticatory-like activity in the guinea pig." Journal of Neurophysiology 63, no. 2 (1990): 356–69. http://dx.doi.org/10.1152/jn.1990.63.2.356.
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1. The effects of iontophoretic application of the excitatory amino acid antagonists kynurenic acid (KYN) and DL-2-amino-5-phosphonovaleric acid (APV), as well as the monoamines serotonin (5-HT) and norepinephrine (NE), on extracellularly recorded jaw opener motoneuron [digastric motoneuron (DIG)] discharge during cortically induced rhythmical masticatory-like activity (RMA) were examined in the anesthetized guinea pig. 2. Iontophoretic application of KYN, a broad-spectrum amino acid antagonist, suppressed the motoneuronal discharge evoked by short pulse train stimulation of the cortex for most cells tested. In contrast, iontophoretic application of APV, a specific N-methyl-D-aspartate (NMDA) antagonist, was usually without effect on the motoneuronal discharge evoked by short pulse train stimulation. 3. During RMA evoked by repetitive cortical stimulation, both KYN and APV suppressed rhythmical DIG motoneuronal discharge in many cells tested. 4. These data suggest that excitatory amino acid receptors on jaw opener motoneurons are involved in activation of RMA. It is proposed that the short-latency rapid excitation of jaw opener motoneurons, which occurs during both short pulse train cortical stimulation and RMA induced by repetitive cortical stimulation, is mediated, at least in part, by non-NMDA receptors. It is further suggested that the large-amplitude, long-duration slow rhythmical oscillations, which occur in the membrane potential of jaw opener motoneurons during RMA induced by repetitive cortical stimulation, are mediated, at least in part, by NMDA receptors. 5. Iontophoretic application of NE or 5-HT with low currents (less than 20 nA) produced a facilitation of digastric motoneuronal discharge during cycle-triggered glutamate application, short pulse train cortical stimulation, and RMA evoked by repetitive cortical stimulation. These facilitatory effects on motoneuronal discharge started within 1 min of drug application, reached a peak at approximately 3 min that persisted for several minutes after the application period, and recovered to control levels within 10-15 min. Direct application of NE or 5-HT, in the absence of chemical or synaptic activation, failed to activate these motoneurons. However, iontophoretic application of either monoamine could facilitate and bring to threshold rhythmical motoneuronal discharges during subthreshold repetitive cortical stimulation. 6. Iontophoretic application of methysergide, a 5-HT antagonist, and phentolamine, an alpha adrenoreceptor blocker, both produced a selective and reversible blockade of the facilitatory effects of 5-HT and NE, respectively, on motoneuronal discharge during cortically induced RMA. In contrast, iontophoretic application of sotalol, a beta adrenoreceptor blocker, had no effect on the NE-induced facilitation of RMA.(ABSTRACT TRUNCATED AT 400 WORDS)
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Noll, Kyle, Priscella Asman, Katherine Connelly, et al. "NCOG-14. INTRAOPERATIVE COGNITIVE-LINGUISTIC MAPPING GUIDED BY VISUALIZATION OF GAMMA BAND MODULATION ELECTROCORTICOGRAMS: PROOF OF CONCEPT IN A PATIENT WITH LEFT TEMPORAL AND OCCIPITAL LOW-GRADE ASTROCYTOMA." Neuro-Oncology 24, Supplement_7 (2022): vii200. http://dx.doi.org/10.1093/neuonc/noac209.767.
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Abstract OBJECTIVE Determine the feasibility and preliminary utility of a novel approach to intraoperative brain mapping guided by visualization of electrocorticography (ECoG) heat maps. METHODS A 39-year-old male with a biopsy-proven left posterior temporal and occipital WHO grade II IDH-mutant astrocytoma underwent awake craniotomy with intraoperative language mapping. Language mapping utilized a dual iPad stimulus presentation system (NeuroMapper) coupled to a portable real-time neural signal processing system capable of both recording cortical activity and delivering direct cortical stimulation in a closed-loop fashion. An ECoG grid (4x8 with 1cm pitch) which covered the majority of the left temporal lobe was used to assess oscillatory cortical activity during administration of language paradigms including object, action, auditory descriptive, and written descriptive naming. ECoG recording and cortical stimulation were synchronized with stimulus presentation via a photosensor attached to the patient-facing tablet. Gamma band modulations in response to language paradigms at each electrode were processed in real-time and visualized as heat maps in MATLAB/Simulink. Following recording and visualization, bipolar direct cortical stimulation from the grid was conducted for each neighboring electrode pair (up to an intensity of 6 mA) during administration of language tasks. RESULTS Despite mild fluent aphasia, a large set of reliable baseline stimuli were obtained for the language mapping paradigms. All naming paradigms resulted in strongest heat map activation at electrode 12 located in the anterior to mid superior temporal gyrus. During stimulation, consistent speech arrest was observed across all paradigms when stimulating electrode pair 11-12, indicating good correspondence with ECoG heat map recordings. Additionally, this region corresponded well with posterior language network representation via resting-state fMRI. CONCLUSION Intraoperative real-time visualization of task-based ECoG gamma band modulation is feasible and may help identify targets for direct cortical stimulation. If validated, this may improve the efficiency and accuracy of intraoperative language mapping.
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R.*, Rusina, Barek S., Vaculín S., Azerad J., and Rokyta R. "Cortical stimulation and tooth pulp evoked potentials in rats: A model of direct anti-nociception." Acta Neurobiologiae Experimentalis 70, no. 1 (2010): 47–55. http://dx.doi.org/10.55782/ane-2010-1773.
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While the effect of cortex stimulation on pain control is widely accepted, its physiological basis remains poorly understood. We chose an animal model of pain to study the influence of sensorimotor cortex stimulation on tooth pulp stimulation evoked potentials (TPEPs). Fifteen awake rats implanted with tooth pulp, cerebral cortex, and digastric muscle electrodes were divided into three groups, receiving 60 Hz, 40 Hz and no cortical stimulation, respectively. TPEPs were recorded before, one, three and five hours after continuous stimulation. We observed an inverse relationship between TPEP amplitude and latency with increasing tooth pulp stimulation. The amplitudes of the early components of TPEPs increased and their latency decreased with increasing tooth pulp stimulation intensity. Cortical stimulation decreased the amplitude of TPEPs; however, neither the latencies of TPEPs nor the jaw-opening reflex were changed after cortical stimulation. The decrease in amplitude of TPEPs after cortical stimulation may reflect its anti-nociceptive effect.
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Wong, Pei-Ling, Yea-Ru Yang, Shih-Fong Huang, and Ray-Yau Wang. "Effects of Transcranial Direct Current Stimulation Followed by Treadmill Training on Dual-Task Walking and Cortical Activity in Chronic Stroke: A Double-Blinded Randomized Controlled Trial." Journal of Rehabilitation Medicine 55 (March 21, 2023): jrm00379. http://dx.doi.org/10.2340/jrm.v55.5258.
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Objective: To explore the effects of transcranial direct current stimulation followed by treadmill training on dual-task gait performance and contralesional cortical activity in chronic stroke patients.Methods: Forty-five chronic stroke participants were randomized into 3 groups: a bilateral transcranial direct current stimulation and treadmill training group; a cathodal transcranial direct current stimulation and treadmill training group; and a sham transcranial direct current stimulation and treadmill training group for 50 min per session (20 min transcranial direct current stimulation followed by 30 min treadmill training), 3 sessions per week for 4 weeks. Outcome measures included cognitive dual-task walking, motor dual-task walking, walking performance, contralesional cortical activity, and lower-extremity motor control.Results: The cathodal transcranial direct current stimulation + treadmill training group showed significantly greater improvements in cognitive dual-task walking speed than the other groups (p cathodal vs sham = 0.006, p cathodal vs bilateral = 0.016). In the cathodal transcranial direct current stimulation + treadmill training group the silent period duration increased significantly more than in the other groups (p < 0.05). Changes in motor evoked potentials in the cathodal transcranial direct current stimulation + treadmill training group were greater than those in the sham transcranial direct current stimulation + treadmill training group (p < 0.05). No significant changes were observed in the bilateral transcranial direct current stimulation + treadmill training group.Conclusion: Cathodal transcranial direct current stimulation followed by treadmill training is an effective intervention for improving cognitive dual-task walking and modulating contralesional cortical activity in chronic stroke. No beneficial effects were observed after bilateral transcranial direct current stimulation and treadmill training.LAY ABSTRACTDual-task walking is essential for daily functioning, both at home and socially. This study explored the effects of transcranial direct current stimulation followed by treadmill training on dual-task gait performance and contralesional cortical activity in chronic stroke patients. A total of 45 chronic stroke patients were randomized to 1 of 3 groups: a bilateral transcranial direct current stimulation and treadmill training group, a cathodal transcranial direct current stimulation and treadmill training group, or a sham transcranial direct current stimulation and treadmill training group for 50 min per session, 3 sessions per week for 4 weeks. Cognitive dual-task walking, motor dual-task walking, walking performance, contralesional cortical activity, and lower-extremity motor control of the affected side were measured before and after the intervention. The results show that cathodal transcranial direct current stimulation followed by treadmill training is an effective intervention for improving cognitive dual-task walking and modulating contralesional cortical activityin individuals with chronic stroke.
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Krings, Timo, Bradley R. Buchbinder, William E. Butler, et al. "Stereotactic Transcranial Magnetic Stimulation: Correlation with Direct Electrical Cortical Stimulation." Neurosurgery 41, no. 6 (1997): 1319–26. http://dx.doi.org/10.1097/00006123-199712000-00016.
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Schuh, Lori, and Ivo Drury. "Intraoperative electrocorticography and direct cortical electrical stimulation." Seminars in Anesthesia, Perioperative Medicine and Pain 16, no. 1 (1997): 46–55. http://dx.doi.org/10.1016/s0277-0326(97)80007-4.
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Oishi, M., K. Suzuki, O. Sasaki, et al. "Crossed aphasia elicited by direct cortical stimulation." Neurology 67, no. 7 (2006): 1306–7. http://dx.doi.org/10.1212/01.wnl.0000238468.84401.d4.
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Luders, H. O., I. Derakhshan, M. Oishi, et al. "CROSSED APHASIA ELICITED BY DIRECT CORTICAL STIMULATION." Neurology 68, no. 19 (2007): 1638–40. http://dx.doi.org/10.1212/01.wnl.0000265607.23814.05.
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Sehatpour, Pejman, Devin Adair, Stephanie Rohrig, et al. "Cortical Modulation using Transcranial Direct Current Stimulation." Brain Stimulation 7, no. 2 (2014): e4. http://dx.doi.org/10.1016/j.brs.2014.01.017.
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Sehatpour, Pejman, Devin Adair, Stephanie Rohrig, Joanna DiCostanzo, and Daniel C. Javitt. "Transcranial Direct Current Stimulation Modulates Cortical Networks." Brain Stimulation 10, no. 1 (2017): e7. http://dx.doi.org/10.1016/j.brs.2016.11.040.
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Taube, Wolfgang, Martin Schubert, Markus Gruber, Sandra Beck, Michael Faist, and Albert Gollhofer. "Direct corticospinal pathways contribute to neuromuscular control of perturbed stance." Journal of Applied Physiology 101, no. 2 (2006): 420–29. http://dx.doi.org/10.1152/japplphysiol.01447.2005.
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The antigravity soleus muscle (Sol) is crucial for compensation of stance perturbation. A corticospinal contribution to the compensatory response of the Sol is under debate. The present study assessed spinal, corticospinal, and cortical excitability at the peaks of short- (SLR), medium- (MLR), and long-latency responses (LLR) after posterior translation of the feet. Transcranial magnetic stimulation (TMS) and peripheral nerve stimulation were individually adjusted so that the peaks of either motor evoked potential (MEP) or H reflex coincided with peaks of SLR, MLR, and LLR, respectively. The influence of specific, presumably direct, corticospinal pathways was investigated by H-reflex conditioning. When TMS was triggered so that the MEP arrived in the Sol at the same time as the peaks of SLR and MLR, EMG remained unaffected. Enhanced EMG was observed when the MEP coincided with the LLR peak ( P < 0.001). Similarly, conditioning of the H reflex by subthreshold TMS facilitated H reflexes only at LLR ( P < 0.001). The earliest facilitation after perturbation occurred after 86 ms. The TMS-induced H-reflex facilitation at LLR suggests that increased cortical excitability contributes to the augmentation of the LLR peaks. This provides evidence that the LLR in the Sol muscle is at least partly transcortical, involving direct corticospinal pathways. Additionally, these results demonstrate that ∼86 ms after perturbation, postural compensatory responses are cortically mediated.
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Rothwell, John. "Transcranial brain stimulation: Past and future." Brain and Neuroscience Advances 2 (January 2018): 239821281881807. http://dx.doi.org/10.1177/2398212818818070.
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This article provides a brief summary of the history of transcranial methods for stimulating the human brain in conscious volunteers and reviews the methodology and physiology of transcranial magnetic stimulation and transcranial direct current stimulation. The former stimulates neural axons and generates action potentials and synaptic activity, whereas the latter polarises the membrane potential of neurones and changes their sensitivity to ongoing synaptic inputs. When coupled with brain imaging methods such as functional magnetic resonance imaging or electroencephalography, transcranial magnetic stimulation can be used to chart connectivity within the brain. In addition, because it induces artificial patterns of activity that interfere with ongoing information processing within a cortical area, it is frequently used in cognitive psychology to produce a short-lasting ‘virtual lesion’. Both transcranial magnetic stimulation and transcranial direct current stimulation can produce short-lasting changes in synaptic excitability and associated changes in behaviour that are presently the source of much research for their therapeutic potential.
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Joshi, Rajat, Sainath Murali, and Nivethida Thirugnanasambandam. "Behavioral Validation of Individualized Low-Intensity Transcranial Electrical Stimulation (tES) Protocols." eneuro 10, no. 12 (2023): ENEURO.0374–22.2023. http://dx.doi.org/10.1523/eneuro.0374-22.2023.
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AbstractLarge interindividual variability in the effects of low-intensity transcranial electrical stimulation (tES) considerably limits its potential for clinical applications. It has been recently proposed that individualizing stimulation dose by accounting for interindividual anatomic differences would reduce the variability in electric fields (E-fields) over the targeted cortical site and therefore produce more consistent behavioral outcomes. However, improvement in behavioral outcomes following individualized dose tES has never been compared with that of conventional fixed dose tES. In this study, we aimed to empirically evaluate the effect of individualized dose tES on behavior and further compare it with the effects of sham and fixed dose stimulations. We conducted a single-blinded, sham-controlled, repeated-measures study to examine the impact of transcranial direct current stimulation on motor learning and that of transcranial alternating current stimulation on the working memory of 42 healthy adult individuals. Each participant underwent three sessions of tES, receiving fixed dose, individualized dose, or sham stimulation over the targeted brain region for the entire behavioral task. Our results showed that the individualized dose reduced the variability in E-fields at the targeted cortical surfaces. However, there was no significant effect of tES on behavioral outcomes. We argue that although the stimulation dose and E-field intensity at the targeted cortical site are linearly correlated, the effect of E-fields on behavior seems to be more complex. Effective optimization of tES protocols warrants further research considering both neuroanatomical and functional aspects of behavior.
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Sehm, Bernhard, Alexander Schäfer, Judy Kipping, et al. "Dynamic modulation of intrinsic functional connectivity by transcranial direct current stimulation." Journal of Neurophysiology 108, no. 12 (2012): 3253–63. http://dx.doi.org/10.1152/jn.00606.2012.
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Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique capable of modulating cortical excitability and thereby influencing behavior and learning. Recent evidence suggests that bilateral tDCS over both primary sensorimotor cortices (SM1) yields more prominent effects on motor performance in both healthy subjects and chronic stroke patients than unilateral tDCS over SM1. To better characterize the underlying neural mechanisms of this effect, we aimed to explore changes in resting-state functional connectivity during both stimulation types. In a randomized single-blind crossover design, 12 healthy subjects underwent functional magnetic resonance imaging at rest before, during, and after 20 min of unilateral, bilateral, and sham tDCS stimulation over SM1. Eigenvector centrality mapping (ECM) was used to investigate tDCS-induced changes in functional connectivity patterns across the whole brain. Uni- and bilateral tDCS over SM1 resulted in functional connectivity changes in widespread brain areas compared with sham stimulation both during and after stimulation. Whereas bilateral tDCS predominantly modulated changes in primary and secondary motor as well as prefrontal regions, unilateral tDCS affected prefrontal, parietal, and cerebellar areas. No direct effect was seen under the stimulating electrode in the unilateral condition. The time course of changes in functional connectivity in the respective brain areas was nonlinear and temporally dispersed. These findings provide evidence toward a network-based understanding regarding the underpinnings of specific tDCS interventions.
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Fregni, Felipe, Paulo S. Boggio, Marcelo C. Santos, et al. "Noninvasive cortical stimulation with transcranial direct current stimulation in Parkinson's disease." Movement Disorders 21, no. 10 (2006): 1693–702. http://dx.doi.org/10.1002/mds.21012.
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Siever, Dave. "Stimulation Technologies: "New" Trends in "Old" Techniques." Biofeedback 43, no. 4 (2015): 180–92. http://dx.doi.org/10.5298/1081-5937-43.04.11.
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Optimal functioning of the brain and mind is essential for good mental health and well-being. Unfortunately, disruptions in specific brain region function may arise for a variety of reasons, which include adverse genetic predispositions, poor nutrition, illness and cerebral accidents, developmental hormonal shifts, and negative life events resulting in overload and stress reactions. Fortunately, there are low-cost, easy-to-use, and effective electronic brain-stimulating technologies available today. These stimulation technologies include audiovisual entrainment (AVE) devices (e.g., light and sound machines), as well as electrostimulation technologies such as cranio-electro stimulation and transcranial direct current stimulation. The instruments are all designed to aid individuals with modulating their own cortical arousal levels, whether to regain lost functionality or to enhance outcomes such as improved social interactions, athletic performance, mathematical problem-solving, or creating new art and music. This article reviews a range of current techniques used for stimulating and modulating brain regions for positive gain.
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Biton, Victor, Miguel E. Fiol, John R. Gates, and Robert E. Maxwell. "Inhibitory Sensory Locus Defined by Direct Cortical Stimulation." Journal of Clinical Neurophysiology 5, no. 4 (1988): 338. http://dx.doi.org/10.1097/00004691-198810000-00040.
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Kim, Paul E., and Manbir Singh. "Functional magnetic resonance imaging for brain mapping in neurosurgery." Neurosurgical Focus 15, no. 1 (2003): 1–7. http://dx.doi.org/10.3171/foc.2003.15.1.1.
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One of the most pertinent applications of the principle primum non nocere (first do no harm) is in the optimization of neurosurgical procedures for patients with resectable lesions. The gold standard for identifying eloquent areas of the brain to be avoided in resections is direct cortical stimulation and somatosensory evoked potential monitoring, which is itself an invasive, cumbersome and difficult technique for mapping these areas. Functional magnetic resonance imaging shows great promise as a viable noninvasive alternative to invasive mapping as well as significant current clinical utility in cases in which it cannot yet fully supplant cortical stimulation methods. Ongoing work is directed toward overcoming technical limitations, improved mapping of complex functions such as language and memory, and mapping of white matter tracts.
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Biella, Gerardo, Laura Uva, Ulrich G. Hofmann, and Marco De Curtis. "Associative Interactions Within the Superficial Layers of the Entorhinal Cortex of the Guinea Pig." Journal of Neurophysiology 88, no. 3 (2002): 1159–65. http://dx.doi.org/10.1152/jn.2002.88.3.1159.
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Associative fiber systems in the entorhinal cortex (EC) have been extensively studied in different mammals with tracing techniques. The largest contingent of intra-EC cortico-cortical fibers runs in the superficial layers and is distributed predominantly within longitudinal cortical bands. We studied the patterns of intrinsic EC connectivity in the in vitro isolated guinea pig brain preparation by performing current-source density analysis of field potential laminar profiles recorded with multi-channel silicon probes. The response pattern evoked by stimulation of the lateral olfactory tract was utilized to identify the lateral (l-EC) and medial (m-EC) entorhinal cortex. Stimulation of the deep layers did not evoke consistent responses. Local stimulation of the superficial layers in different portions of the EC induced an early, possibly direct response restricted to layer II–III in the close proximity to the stimulating electrode, followed by a late potential in the superficial layer I, that propagated at distance with a progressively increasing latency. The monosynaptic nature of the delayed response was verified by applying a pairing test. The results demonstrated that stimulation in the rostral-medial part of the EC generated activity restricted to the rostral pole of the l-EC, stimulation of the m-EC induced an associative activation that propagated rostrocaudally within the m-EC, stimulation of the caudal pole of the m-EC induced an additional response directed laterally, and stimulation of the lateral band of the EC determined a prominent longitudinal propagation of neuronal activity, but also induced associative potentials that propagated medially. The results are in partial agreement with the general picture derived from the anatomical studies performed in different species. Even though the largest associative interactions between superficial layers are restricted within either the m-EC or the l-EC, both rostral and caudal stimuli in the EC region close to the rhinal sulcus induced activity that propagated across the border between l- and m-EC.
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Nitsche, M. A., S. Doemkes, T. Karaköse, et al. "Shaping the Effects of Transcranial Direct Current Stimulation of the Human Motor Cortex." Journal of Neurophysiology 97, no. 4 (2007): 3109–17. http://dx.doi.org/10.1152/jn.01312.2006.
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Transcranial DC stimulation (tDCS) induces stimulation polarity-dependent neuroplastic excitability shifts in the human brain. Because it accomplishes long-lasting effects and its application is simple, it is used increasingly. However, one drawback is its low focality, caused by 1) the large stimulation electrode and 2) the functionally effective reference electrode, which is also situated on the scalp. We aimed to increase the focality of tDCS, which might improve the interpretation of the functional effects of stimulation because it will restrict its effects to more clearly defined cortical areas. Moreover, it will avoid unwanted reversed effects of tDCS under the reference electrode, which is of special importance in clinical settings, when a homogeneous shift of cortical excitability is needed. Because current density (current strength/electrode size) determines the efficacy of tDCS, increased focality should be accomplished by 1) reducing stimulation electrode size, but keeping current density constant; or 2) increasing reference electrode size under constant current strength. We tested these hypotheses for motor cortex tDCS. The results show that reducing the size of the motor cortex DC-stimulation electrode focalized the respective tDCS-induced excitability changes. Increasing the size of the frontopolar reference electrode rendered stimulation over this cortex functionally inefficient, but did not compromise the tDCS-generated motor cortical excitability shifts. Thus tDCS-generated modulations of cortical excitability can be focused by reducing the size of the stimulation electrode and by increasing the size of the reference electrode. For future applications of tDCS, such paradigms may help to achieve more selective tDCS effects.
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Picht, Thomas, Sein Schmidt, Stephan Brandt, et al. "Preoperative Functional Mapping for Rolandic Brain Tumor Surgery: Comparison of Navigated Transcranial Magnetic Stimulation to Direct Cortical Stimulation." Neurosurgery 69, no. 3 (2011): 581–89. http://dx.doi.org/10.1227/neu.0b013e3182181b89.
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Abstract BACKGROUND: Transcranial magnetic stimulation (TMS) is the only noninvasive method for presurgical stimulation mapping of cortical function. Recent technical advancements have significantly increased the focality and usability of the method. OBJECTIVE: To compare the accuracy of a 3-dimensional magnetic resonance imaging-navigated TMS system (nTMS) with the gold standard of direct cortical stimulation (DCS). METHODS: The primary motor areas of 20 patients with rolandic tumors were mapped preoperatively with nTMS at 110% of the individual resting motor threshold. Intraoperative DCS was available from 17 patients. The stimulus locations eliciting the largest electromyographic response in the target muscles (“hotspots”) were determined for both methods. RESULTS: The nTMS and DCS hotspots were located on the same gyrus in all cases. The mean ± SEM distance between the nTMS and DCS hotspots was 7.83 ± 1.18 mm for the abductor pollicis brevis (APB) muscle (n = 15) and 7.07 ± 0.88 mm for the tibialis anterior muscle (n = 8). When a low number of DCS stimulations was performed, the distance between the nTMS and DCS hotspots increased substantially (r = −0.86 for APB). After the exclusion of the cases with &lt; 15 DCS APB responses, the mean ± SEM distance between the hotspots was only 4.70 ± 1.09 mm for APB (n = 8). CONCLUSION: Peritumoral mapping of the motor cortex by nTMS agreed well with the gold standard of DCS. Thus, nTMS is a reliable tool for preoperative mapping of motor function.
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Chadaide, Z., S. Arlt, A. Antal, MA Nitsche, N. Lang, and W. Paulus. "Transcranial Direct Current Stimulation Reveals Inhibitory Deficiency In Migraine." Cephalalgia 27, no. 7 (2007): 833–39. http://dx.doi.org/10.1111/j.1468-2982.2007.01337.x.
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The issue of interictal excitability of cortical neurons in migraine patients is controversial: some studies have reported hypo-, others hyperexcitability. The aim of the present study was to observe the dynamics of this basic interictal state by further modulating the excitability level of the visual cortex using transcranial direct current stimulation (tDCS) in migraineurs with and without aura. In healthy subjects anodal tDCS decreases, cathodal stimulation increases transcranial magnetic stimulation (TMS)-elicited phosphene thresholds (PT), which is suggested as a representative value of visual cortex excitability. Compared with healthy controls, migraine patients tended to show lower baseline PT values, but this decrease failed to reach statistical significance. Anodal stimulation decreased phosphene threshold in migraineurs similarly to controls, having a larger effect in migraineurs with aura. Cathodal stimulation had no significant effect in the patient groups. This result strengthens the notion of deficient inhibitory processes in the cortex of migraineurs, which is selectively revealed by activity-modulating cortical input.
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Cherney, Leora R. "Cortical Stimulation and Aphasia: The State of the Science." Perspectives on Neurophysiology and Neurogenic Speech and Language Disorders 18, no. 1 (2008): 33–39. http://dx.doi.org/10.1044/nnsld18.1.33.
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Abstract Purpose: Biological approaches to aphasia rehabilitation involve procedures aimed to alter brain anatomy and physiology so that language function can be restored. One such approach is the application of electrical stimulation to the cerebral cortex to facilitate brain plasticity and enhance stroke recovery. Method: This article discusses the rationale for the application of cortical stimulation and reviews three different methods of delivering cortical brain stimulation — repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), and epidural cortical stimulation. Each of these methods has been applied to the rehabilitation of language after stroke, and some of the key studies that have addressed the use of cortical stimulation as a potential treatment for post-stroke aphasia are described. Conclusions: Pilot results suggest a potential role for cortical stimulation as an adjuvant strategy in aphasia rehabilitation. Further investigation of each method of stimulation and its impact on language recovery is warranted. Suggestions for the direction of future research are discussed.
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Cohen, L. G., S. Sato, K. Kufta, and M. Hallett. "Attenuation of somatosensory perception by transcranial magnetic stimulation and direct cortical stimulation." Electroencephalography and Clinical Neurophysiology 75 (January 1990): S25—S26. http://dx.doi.org/10.1016/0013-4694(90)91809-4.
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Oda, Nobuhito, Masami Ishii, and Bong-Kyun Kim. "The efficacy of direct motor cortical stimulation for sensori-motor cortical lesions." Clinical Neurology and Neurosurgery 99 (July 1997): S33. http://dx.doi.org/10.1016/s0303-8467(97)81392-3.
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Henseler, Ilona, Andreas Mädebach, Sonja A. Kotz, and Jörg D. Jescheniak. "Modulating Brain Mechanisms Resolving Lexico-semantic Interference during Word Production: A Transcranial Direct Current Stimulation Study." Journal of Cognitive Neuroscience 26, no. 7 (2014): 1403–17. http://dx.doi.org/10.1162/jocn_a_00572.
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The aim of the current study was to shed further light on control processes that shape semantic access and selection during speech production. These processes have been linked to differential cortical activation in the left inferior frontal gyrus (IFG) and the left middle temporal gyrus (MTG); however, the particular function of these regions is not yet completely elucidated. We applied transcranial direct current stimulation to the left IFG and the left MTG (or sham stimulation) while participants named pictures in the presence of associatively related, categorically related, or unrelated distractor words. This direct modulation of target regions can help to better delineate the functional role of these regions in lexico-semantic selection. Independent of stimulation, the data show interference (i.e., longer naming latencies) with categorically related distractors and facilitation (i.e., shorter naming latencies) with associatively related distractors. Importantly, stimulation location interacted with the associative effect. Whereas the semantic interference effect did not differ between IFG, MTG, and sham stimulations, the associative facilitation effect was diminished under MTG stimulation. Analyses of latency distributions suggest this pattern to result from a response reversal. Associative facilitation occurred for faster responses, whereas associative interference resulted in slower responses under MTG stimulation. This reduction of the associative facilitation effect under transcranial direct current stimulation may be caused by an unspecific overactivation in the lexicon or by promoting competition among associatively related representations. Taken together, the results suggest that the MTG is especially involved in the processes underlying associative facilitation and that semantic interference and associative facilitation are linked to differential activation in the brain.
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Ille, Sebastian, Nico Sollmann, Theresa Hauck, et al. "Combined noninvasive language mapping by navigated transcranial magnetic stimulation and functional MRI and its comparison with direct cortical stimulation." Journal of Neurosurgery 123, no. 1 (2015): 212–25. http://dx.doi.org/10.3171/2014.9.jns14929.
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OBJECT Repetitive navigated transcranial magnetic stimulation (rTMS) is now increasingly used for preoperative language mapping in patients with lesions in language-related areas of the brain. Yet its correlation with intraoperative direct cortical stimulation (DCS) has to be improved. To increase rTMS's specificity and positive predictive value, the authors aim to provide thresholds for rTMS's positive language areas. Moreover, they propose a protocol for combining rTMS with functional MRI (fMRI) to combine the strength of both methods. METHODS The authors performed multimodal language mapping in 35 patients with left-sided perisylvian lesions by using rTMS, fMRI, and DCS. The rTMS mappings were conducted with a picture-to-trigger interval (PTI, time between stimulus presentation and stimulation onset) of either 0 or 300 msec. The error rates (ERs; that is, the number of errors per number of stimulations) were calculated for each region of the cortical parcellation system (CPS). Subsequently, the rTMS mappings were analyzed through different error rate thresholds (ERT; that is, the ER at which a CPS region was defined as language positive in terms of rTMS), and the 2-out-of-3 rule (a stimulation site was defined as language positive in terms of rTMS if at least 2 out of 3 stimulations caused an error). As a second step, the authors combined the results of fMRI and rTMS in a predefined protocol of combined noninvasive mapping. To validate this noninvasive protocol, they correlated its results to DCS during awake surgery. RESULTS The analysis by different rTMS ERTs obtained the highest correlation regarding sensitivity and a low rate of false positives for the ERTs of 15%, 20%, 25%, and the 2-out-of-3 rule. However, when comparing the combined fMRI and rTMS results with DCS, the authors observed an overall specificity of 83%, a positive predictive value of 51%, a sensitivity of 98%, and a negative predictive value of 95%. CONCLUSIONS In comparison with fMRI, rTMS is a more sensitive but less specific tool for preoperative language mapping than DCS. Moreover, rTMS is most reliable when using ERTs of 15%, 20%, 25%, or the 2-out-of-3 rule and a PTI of 0 msec. Furthermore, the combination of fMRI and rTMS leads to a higher correlation to DCS than both techniques alone, and the presented protocols for combined noninvasive language mapping might play a supportive role in the language-mapping assessment prior to the gold-standard intraoperative DCS.
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Nitsche, Michael A., Astrid Schauenburg, Nicolas Lang, et al. "Facilitation of Implicit Motor Learning by Weak Transcranial Direct Current Stimulation of the Primary Motor Cortex in the Human." Journal of Cognitive Neuroscience 15, no. 4 (2003): 619–26. http://dx.doi.org/10.1162/089892903321662994.
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Transcranially applied weak direct currents are capable of modulating motor cortical excitability in the human. Anodal stimulation enhances excitability, cathodal stimulation diminishes it. Cortical excitability changes accompany motor learning. Here we show that weak direct currents are capable of improving implicit motor learning in the human. During performance of a serial reaction time task, the primary motor cortex, premotor, or prefrontal cortices were stimulated contralaterally to the performing hand. Anodal stimulation of the primary motor cortex resulted in increased performance, whereas stimulation of the remaining cortices had no effect. We conclude that the primary motor cortex is involved in the acquisition and early consolidation phase of implicit motor learning.
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Baeken, C. "tDCS home based treatment following accelerated dTMS in the elderly depressed." European Psychiatry 66, S1 (2023): S45—S46. http://dx.doi.org/10.1192/j.eurpsy.2023.167.
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AbstractWith a growing number of elderly persons, geriatric depression - associated with important morbidity and mortality- is becoming a significant health problem. Given the risk of polypharmacy and increased side effects, alternative non pharmaceutical treatments such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) may be solution. Recently, the FDA approved deep brain TMS (dTMS) for depression, not only stimulating deeper cortical areas but response and remission rates may be better, especially in elderly populations. Nevertheless, beneficial follow-up options following rTMS treatment remains to be determined. Therefore, one week after the last accelerated dTMS, all patients followed a 3 week open label tDCS with a home-use device. Study rationale and preliminary findings will be discussed.Disclosure of InterestNone Declared
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Lim, Sung Hyuk, and Min Hwan Jang. "Technical Considerations of Effective Direct Cortical and Subcortical Stimulation." Korean Journal of Clinical Laboratory Science 54, no. 2 (2022): 157–62. http://dx.doi.org/10.15324/kjcls.2022.54.2.157.
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Bialik, Paul Shkurovich. "38. Mapping eloquent cortical areas with direct electrical stimulation." Clinical Neurophysiology 127, no. 9 (2016): e311. http://dx.doi.org/10.1016/j.clinph.2016.05.313.
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Speth, C., J. Speth, and T. Harley. "Transcranial direct current stimulation and cortical indicators of relaxation." Brain Stimulation 8, no. 2 (2015): 405. http://dx.doi.org/10.1016/j.brs.2015.01.290.
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Sun, Yan, Sameer C. Dhamne, Alejandro Carretero‐Guillén, et al. "Drug‐Responsive Inhomogeneous Cortical Modulation by Direct Current Stimulation." Annals of Neurology 88, no. 3 (2020): 489–502. http://dx.doi.org/10.1002/ana.25822.
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Jefferson, Samantha, Satish Mistry, Salil Singh, John Rothwell, and Shaheen Hamdy. "Characterizing the application of transcranial direct current stimulation in human pharyngeal motor cortex." American Journal of Physiology-Gastrointestinal and Liver Physiology 297, no. 6 (2009): G1035—G1040. http://dx.doi.org/10.1152/ajpgi.00294.2009.
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Transcranial direct current stimulation (tDCS) is a novel intervention that can modulate brain excitability in health and disease; however, little is known about its effects on bilaterally innervated systems such as pharyngeal motor cortex. Here, we assess the effects of differing doses of tDCS on the physiology of healthy human pharyngeal motor cortex as a prelude to designing a therapeutic intervention in dysphagic patients. Healthy subjects ( n = 17) underwent seven regimens of tDCS (anodal 10 min 1 mA, cathodal 10 min 1 mA, anodal 10 min 1.5 mA, cathodal 10 min 1.5 mA, anodal 20 min 1 mA, cathodal 20 min 1 mA, Sham) on separate days, in a double blind randomized order. Bihemispheric motor evoked potential (MEP) responses to single-pulse transcranial magnetic stimulation (TMS) as well as intracortical facilitation (ICF) and inhibition (ICI) were recorded using a swallowed pharyngeal catheter before and up to 60 min following the tDCS. Compared with sham, both 10 min 1.5 mA and 20 min 1 mA anodal stimulation induced increases in cortical excitability in the stimulated hemisphere (+44 ± 17% and +59 ± 16%, respectively; P < 0.005) whereas only 10 min 1.5 mA cathodal stimulation induced inhibition (−26 ± 4%, P = 0.02). There were neither contralateral hemisphere changes nor any evidence for ICI or ICF in driving the ipsilateral effects. In conclusion, anodal tDCS can alter pharyngeal motor cortex excitability in an intensity-dependent manner, with little evidence for transcallosal spread. Anodal stimulation may therefore provide a useful means of stimulating pharyngeal cortex and promoting recovery in dysphagic patients.
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Gomez-Tames, Jose, Akimasa Hirata, Manabu Tamura, and Yoshihiro Muragaki. "Corticomotoneuronal Model for Intraoperative Neurophysiological Monitoring During Direct Brain Stimulation." International Journal of Neural Systems 29, no. 01 (2019): 1850026. http://dx.doi.org/10.1142/s0129065718500260.
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Intraoperative neurophysiological monitoring during brain surgery uses direct cortical stimulation to map the motor cortex by recording muscle activity induced by the excitation of alpha motor neurons (MNs). Computational models have been used to understand local brain stimulation. However, a computational model revealing the stimulation process from the cortex to MNs has not yet been proposed. Thus, the aim of the current study was to develop a corticomotoneuronal (CMN) model to investigate intraoperative stimulation during surgery. The CMN combined the following three processes into one system for the first time: (1) induction of an electric field in the brain based on a volume conductor model; (2) activation of pyramidal neuron (PNs) with a compartment model; and (3) formation of presynaptic connections of the PNs to MNs using a conductance-based synaptic model coupled with a spiking model. The implemented volume conductor model coupled with the axon model agreed with experimental strength-duration curves. Additionally, temporal/spatial and facilitation effects of CMN synapses were implemented and verified. Finally, the integrated CMN model was verified with experimental data. The results demonstrated that our model was necessary to describe the interaction between frequency and pulses to assess the difference between low-frequency and multi-pulse high-frequency stimulation in cortical stimulation. The proposed model can be used to investigate the effect of stimulation parameters on the cortex to optimize intraoperative monitoring.
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Picht, Thomas, Sven Mularski, Bjoern Kuehn, Peter Vajkoczy, Theodoros Kombos, and Olaf Suess. "Navigated Transcranial Magnetic Stimulation for Preoperative Functional Diagnostics in Brain Tumor Surgery." Operative Neurosurgery 65, suppl_6 (2009): ons93—ons99. http://dx.doi.org/10.1227/01.neu.0000348009.22750.59.
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Abstract Objective: Transcranial magnetic stimulation (TMS) is a noninvasive method for analyzing cortical function. To utilize TMS for presurgical functional diagnostics, the magnetic impulse must be precisely targeted by stereotactically positioning the coil. The aim of this study was to evaluate the usefulness of TMS for operation planning when combined with a sensor-based electromagnetic navigation system (nTMS). Methods: Preoperative functional mapping with nTMS was performed in 10 patients with rolandic tumors. Intraoperative mapping was performed with the “gold standard” of direct cortical stimulation. Stimulation was performed in the same predefined 5-mm raster for both modalities, and the results were compared. Results: In regard to the 5-mm mapping raster, the centers of gravity of nTMS and direct cortical stimulation were located at the same spot in 4 cases and at neighboring spots in the remaining 6 cases. The mean distance between the tumor and the nearest motor response (“safety margin”) was 7.9 mm (range, 5–15 mm; standard deviation, 3.2 mm) for nTMS and 6.6 mm (range, 0–12 mm; standard deviation, 3.4 mm) for direct cortical stimulation. Conclusion: nTMS allowed for reliable, precise application of the magnetic impulse, and the peritumoral somatotopy corresponded well between the 2 modalities in all 10 cases. nTMS is a promising method for preoperative functional mapping in motor cortex tumor surgery.
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Karakis, Ioannis, Beth A. Leeman-Markowski, Catherine L. Leveroni, et al. "Intra-stimulation discharges: An overlooked cortical electrographic entity triggered by direct electrical stimulation." Clinical Neurophysiology 126, no. 5 (2015): 882–88. http://dx.doi.org/10.1016/j.clinph.2014.08.011.
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Weaver, Kurt E., David J. Caldwell, Jeneva A. Cronin, et al. "Concurrent Deep Brain Stimulation Reduces the Direct Cortical Stimulation Necessary for Motor Output." Movement Disorders 35, no. 12 (2020): 2348–53. http://dx.doi.org/10.1002/mds.28255.
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