共查询到20条相似文献，搜索用时 109 毫秒
1.
Vishal Rawji Matteo Ciocca André Zacharia David Soares Dennis Truong Marom Bikson John Rothwell Sven Bestmann 《Brain stimulation》2018,11(2):289-298
Background
Measurements and models of current flow in the brain during transcranial Direct Current Stimulation (tDCS) indicate stimulation of regions in-between electrodes. Moreover, the folded cortex results in local fluctuations in current flow intensity and direction, and animal studies suggest current flow direction relative to cortical columns determines response to tDCS.Methods
Here we test this idea by using Transcranial Magnetic Stimulation Motor Evoked Potentials (TMS-MEP) to measure changes in corticospinal excitability following tDCS applied with electrodes aligned orthogonal (across) or parallel to M1 in the central sulcus.Results
Current flow models predicted that the orthogonal electrode montage produces consistently oriented current across the hand region of M1 that flows along cortical columns, while the parallel electrode montage produces non-uniform current directions across the M1 cortical surface. We find that orthogonal, but not parallel, orientated tDCS modulates TMS-MEPs. We also show modulation is sensitive to the orientation of the TMS coil (PA or AP), which is thought to select different afferent pathways to M1.Conclusions
Our results are consistent with tDCS producing directionally specific neuromodulation in brain regions in-between electrodes, but shows nuanced changes in excitability that are presumably current direction relative to column and axon pathway specific. We suggest that the direction of current flow through cortical target regions should be considered for targeting and dose-control of tDCS. 相似文献2.
Background
Recent studies have shown that neurophysiological outcomes of transcranial direct current stimulation (TDCS) are influenced by current flow in brain regions between the electrodes, and in particular the orientation of current flow relative to the cortical surface.Objective
We asked whether the directional effects of TDCS on physiological measures in the motor system would also be observed on motor behaviours.Methods
We applied TDCS during the practice of a ballistic movement task to test whether it affected learning or the retention of learning 48?h later. TDCS electrodes were oriented perpendicular to the central sulcus and two current orientations were used (posterior-anterior, TDCSPA; and anterior-posterior, TDCSAP). Transcranial magnetic stimulation (TMS) was used to assess whether changes in corticospinal excitability reflected any behavioural changes.Results
Directional TDCSAP impaired the retention of learning on the ballistic movement task compared to TDCSPA and a sham condition. Although TDCSPA had no effect on learning or retention, it blocked the typical increase in corticospinal excitability after a period of motor practice.Conclusions
Our results extend on previous reports of TDCS producing directionally specific changes in neurophysiological outcomes by showing that current direction through a cortical target also impacts upon behavioural outcomes. In addition, changes in corticospinal excitability after a period of motor practice are not causally linked to behavioural learning. 相似文献3.
Federico Ranieri Gianluca Coppola Gabriella Musumeci Fioravante Capone Giovanni Di Pino Vincenzo Parisi Vincenzo Di Lazzaro 《Brain stimulation》2019,12(3):705-713
Background
Repetitive convergent inputs to a single post-synaptic neuron can induce long-term potentiation (LTP) or depression (LTD) of synaptic activity in a spike timing-dependent manner.Objective
Here we set a protocol of visual paired associative stimulation (vPAS) of the primary visual cortex (V1) in humans to induce persistent changes in the excitatory properties of V1 with a spike timing rule.Methods
We provided convergent inputs to V1 by coupling transcranial magnetic stimulation (TMS) pulses of the occipital cortex with peripheral visual inputs, at four interstimulus intervals of ?50/-25/+25/+50 ms relative to the visual evoked potential (VEP) P1 latency. We analysed VEP amplitude and delayed habituation before and up to 10 min after each vPAS protocol.Results
VEP amplitude was reduced after vPAS+25. Delayed VEP habituation was increased after vPAS-25 while it was reduced after vPAS+25.Conclusions
We provide evidence that associative bidirectional synaptic plasticity is a feature not only of the sensorimotor but also of the human visual system. 相似文献4.
Martin Sommer Matteo Ciocca Raffaella Chieffo Paul Hammond Andreas Neef Walter Paulus John C. Rothwell Ricci Hannah 《Brain stimulation》2018,11(3):558-565
Background
Biphasic pulses produced by most commercially available TMS machines have a cosine waveform, which makes it difficult to study the interaction between the two phases of stimulation.Objective
We used a controllable pulse TMS (cTMS) device delivering quasi-rectangular pulse outputs to investigate whether monophasic are more effective than biphasic pulses.Methods
Temporally symmetric (“biphasic”) or highly asymmetric (“monophasic”) charge-balanced biphasic stimuli were used to target the hand area of motor cortex in the anterior-posterior (AP) or posterior-anterior (PA) initial current direction.Results
We observed the lowest motor thresholds and shortest motor evoked potential (MEP) latencies with initial PA pulses, and highest thresholds and longest latencies with AP pulses. Increasing pulse symmetry tended to increase threshold with a PA direction whereas it lowered thresholds and shortened latencies with an AP direction. Furthermore, it steepened the MEP input-output curve with both directions.Conclusions
“Biphasic” TMS pulses can be viewed as two monophasic pulses of opposite directions, each stimulating a different set of interneurons with different thresholds (PA?<?AP). At threshold, the reverse phase of an initially PA pulse increases threshold compared with “monophasic” stimulation. At higher intensities, the reverse phase begins to activate AP-sensitive neurones and increase the effectiveness of stimulation above that of a “monophasic” PA pulse. “Biphasic” stimulation with initially AP pulses is dominated at threshold by activation produced by the lower threshold reverse (PA) phase.Significance
The effects of biphasic stimulation are best understood as the summed output of two independent sets of directionally selective neural populations. 相似文献5.
Background
Alpha (8–14?Hz) oscillatory power is linked to cortical excitability and corresponding modulations of sensory evoked potentials and perceptual detection performance. In somatosensory cortex (S1), negative linear and inverted U-shape relationships exist, whereas its effect on the primary motor cortex (M1) is hardly known.Objective
We used real-time EEG-triggered transcranial magnetic stimulation (TMS) of M1 to characterize the relationship between spontaneous sensorimotor mu-alpha power fluctuations at rest and corticospinal excitability.Methods
In 16 subjects, mu-alpha power was continuously monitored over the left sensorimotor cortex, and each 10%-percentile bin of the individual mu-alpha power distribution was repeatedly targeted in pseudorandomized order by single-pulse TMS of left M1, measuring motor evoked potentials (MEP) in the contralateral hand.Results
We found a weak positive relationship between mu-alpha power and MEP amplitude.Conclusion
Sensorimotor mu-alpha power may reflect a net facilitation or disinhibition of M1, possibly resulting from mu-alpha based suppression of excitatory and inhibitory input from S1. 相似文献6.
Michele Dileone Laura Mordillo-Mateos Antonio Oliviero Guglielmo Foffani 《Brain stimulation》2018,11(4):676-688
Background
Transcranial static magnetic field stimulation (tSMS) was recently added to the family of inhibitory non-invasive brain stimulation techniques. However, the application of tSMS for 10–20?min over the motor cortex (M1) induces only short-lasting effects that revert within few minutes.Objective
We examined whether increasing the duration of tSMS to 30?min leads to long-lasting changes in cortical excitability, which is critical for translating tSMS toward clinical applications.Methods
The study comprised 5 experiments in 45 healthy subjects. We assessed the impact of 30-min-tSMS over M1 on corticospinal excitability, as measured by the amplitude of motor evoked potentials (MEPs) and resting motor thresholds (RMTs) to single-pulse transcranial magnetic stimulation (TMS) (experiments 1–2). We then assessed the impact of 30-min-tSMS on intracortical excitability, as measured by short-interval intracortical facilitation (SICF) and short-interval intracortical inhibition (SICI) using paired-pulse TMS protocols (experiments 2–4). We finally assessed the impact of 10-min-tSMS on SICF and SICI (experiment 5).Results
30-min-tSMS decreased MEP amplitude compared to sham for at least 30?min after the end of the stimulation. This long-lasting effect was associated with increased SICF and reduced SICI. 10-min-tSMS –previously reported to induce a short-lasting decrease in MEP amplitude– produced the opposite changes in intracortical excitability, decreasing SICF while increasing SICI.Conclusions
These results suggest a dissociation of intracortical changes in the consolidation from short-lasting to long-lasting decrease of corticospinal excitability induced by tSMS. The long-lasting effects of 30-min-tSMS open the way to the translation of this simple, portable and low-cost technique toward clinical trials. 相似文献7.
Martin Schecklmann Carmen Weidler Peter Eichhammer Göran Hajak Berthold Langguth 《Brain stimulation》2018,11(5):1080-1082
Background
Schizophrenia is associated with changes in inhibitory and facilitatory brain networks which can be assessed by motor cortex excitability.Objective
Here, we investigate differences between large cross-sectional samples of un-medicated and medicated patients with schizophrenia and healthy controls in single- and double-pulse transcranial magnetic stimulation parameters.Methods
We measured right abductor digiti minimi muscle activity in 71 un-medicated, 43 medicated patients and 131 healthy controls. To exclude sample bias analyses were repeated with groups comparable for age and gender (un-medicated: n?=?43; medicated: n?=?38; controls: n?=?49).Results
Un-medicated patients showed increased short-interval intracortical inhibition (SICI) in contrast to medicated patients and healthy controls. No group differences were found for resting and active motor threshold, cortical silent period and intracortical facilitation.Conclusion
Increases in SICI are in contrast to literature and highlight the necessity for large-scaled multi-centric studies with high methodological standards. 相似文献8.
Silvia Casarotto Francesco Turco Angela Comanducci Alessio Perretti Giorgio Marotta Gianni Pezzoli Mario Rosanova Ioannis U. Isaias 《Brain stimulation》2019,12(1):152-160
Background
Cortical dysfunctioning significantly contributes to the pathogenesis of motor symptoms in Parkinson's disease (PD).Objective
We aimed at testing whether an acute levodopa administration has measurable and specific cortical effects possibly related to striatal dopaminergic deficit.Methods
In thirteen PD patients, we measured the electroencephalographic responses to transcranial magnetic stimulation (TMS/EEG) of the supplementary motor area and superior parietal lobule (n?=?8) before and after an acute intake of levodopa. We also performed a single-photon emission computed tomography and [123I]N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)nortropane to identify the more affected and the less affected brain side in each patient, according to the dopaminergic innervation loss of the putamen. Cortical excitability changes before and after an acute intake of levodopa were computed and compared between the more and the less affected brain side at the single-patient as well as at the group level.Results
We found that levodopa intake induces a significant increase (P?<?0.01) of cortical excitability nearby the supplementary motor area in the more affected brain side, greater (P?<?0.025) than in the less affected brain side. Notably, cortical excitability changes nearby the superior parietal lobule were not statistically significant.Conclusions
These results strengthen the idea that dysfunction of specific cortico-subcortical circuits may contribute to pathophysiology of PD symptoms. Most important, they support the use of navigated TMS/EEG as a non-invasive tool to better understand the pathophysiology of PD. 相似文献9.
Robert Guggenberger Dominic Kraus Georgios Naros Maria Teresa Leão Ulf Ziemann Alireza Gharabaghi 《Brain stimulation》2018,11(6):1331-1335
Background
Pairing cortical and peripheral input during motor imagery (MI)-related sensorimotor desynchronization (ERD) modulates corticospinal excitability at the cortical representation (hotspot) of the imagined movement.Objective
To determine the effects of this associative stimulation protocol on the cortical motor map beyond the hotspot.Methods
In healthy subjects, peripheral stimulation through passive hand opening by a robotic orthosis and single-pulse transcranial magnetic stimulation to the respective cortical motor representation were applied in a brain-machine interface environment. State-dependency was investigated by concurrent, delayed or non-specific stimulation with respect to ERD in the beta-band (16–22?Hz) during MI of finger extension.Results
Concurrent stimulation led to increased excitability of an extended motor map. Delayed and non-specific stimulation led to heterogeneous changes, i.e., opposite patterns of increased excitability in either the center or the periphery of the motor map.Conclusion
These results could be instrumental in closed-loop, state-dependent stimulation in the context of neurorehabilitation. 相似文献10.
Xiaoming Du Laura M. Rowland Ann Summerfelt Andrea Wijtenburg Joshua Chiappelli Krista Wisner Peter Kochunov Fow-Sen Choa L. Elliot Hong 《Brain stimulation》2018,11(5):1071-1079
Background
Animal studies suggest that synchronized electrical activities in the brain are regulated by the primary inhibitory and excitatory neurotransmitters gamma-aminobutyric acid (GABA) and glutamate, respectively. Identifying direct evidence that this same basic chemical-electrical neuroscience principle operates in the human brains is critical for translation of neuroscience to pathological research.Objective/Hypothesis
We hypothesize that the background neurochemical concentrations may affect the cortical excitability probed by transcranial magnetic stimulation (TMS).Methods
We used TMS with simultaneous evoked potential recording to probe the cortical excitability and determined how background frontal cortical GABA and glutamate levels measured using magnetic resonance spectroscopy (MRS) modulate frontal electrical activities.Results
We found that TMS-evoked N100 reflects a balance between GABA-inhibitory and glutamate-excitatory levels. About 46% of individual variances in frontal N100 can be explained by their glutamate/GABA ratio (r?=??0.68, p?=?0.001). Both glutamate (r?=??0.51, p?=?0.019) and GABA (r?=?0.55, p?=?0.01) significantly contributed to this relationship but in opposite directions.Conclusion
The current finding encourages additional mechanistic studies to develop TMS evoked N100 as a potential electrophysiological biomarker for translating the known inhibitory GABAergic vs. excitatory glutamatergic chemical-electrical principle from animal brain studies to human brain studies. 相似文献11.
Francesco Di Lorenzo Caterina Motta Sonia Bonnì Nicola Biagio Mercuri Carlo Caltagirone Alessandro Martorana Giacomo Koch 《Brain stimulation》2019,12(1):148-151
Background
Alzheimer's disease (AD) is characterized by a primary impairment of long-term declarative memory caused by deposition of misfolded protein aggregates. Experimental studies showed that AD neuropathological alterations impair synaptic plasticity and memory performance. Transcranial Magnetic Stimulation protocols have been recently introduced to investigate altered mechanisms of cortical plasticity in AD patients.Aim
To investigate relationship between Long-Term Potentiation (LTP)-like cortical plasticity and patients’ neuropsychological performance.Methods
We applied intermittent theta burst stimulation and extensive neuropshycological battery in 75 newly diagnosed AD patients.Results
We found that LTP-like cortical plasticity impairment is selectively associated to a less efficient verbal memory (r?=?0.45; p?=?0.002), but not to other cognitive functions, independently from biomarkers and other demographic and clinical factors.Conclusion
These findings suggest that LTP-like cortical plasticity may represent a neurophysiological surrogate of memory in AD patients by evaluating the weight of pathological changes responsible for cognitive dysfunction. 相似文献12.
Matteo Franza Giuliana Sorrentino Matteo Vissani Andrea Serino Olaf Blanke Michela Bassolino 《Brain stimulation》2019,12(3):693-701
Background
When single pulse transcranial magnetic stimulation (TMS) is applied over the primary motor cortex (M1) with sufficient intensity, it evokes muscular contractions (motor-evoked potentials, MEPs) and muscle twitches (TMS-evoked movements). Participants may also report various hand sensations related to TMS, but the perception elicited by TMS and its relationship to MEPs and evoked movements has not been systematically studied.Objective
The main aim of this work is to evaluate participants' kinesthetic and somatosensory hand perceptions elicited by single-pulse TMS over M1-hand area at different intensities of stimulation and their relation with MEPs and TMS-evoked movements.Methods
We compared the number of MEPs (measured by electromyography), TMS-evoked movements (measured by an accelerometer) and participants' hand perception (measured by verbal report) elicited by TMS at different intensity of stimulation. This way, we estimated the amplitude of MEPs and the acceleration of TMS-evoked movements sufficient to trigger TMS evoked hand perceptions.Results
We found that TMS-evoked hand perceptions are induced at 105% of the individual resting motor threshold, a value significantly different from the threshold inducing MEPs (about 100%) and TMS-evoked movements (about 110%). Our data indicate that only MEPs with an amplitude higher than 0.62 mV and TMS-evoked movements with acceleration higher than 0.42 m/s2 were associated with hand perceptions at threshold.Conclusions
Our data reveal the main features of TMS-evoked hand perception and show that in addition to MEPs and TMS-evoked movements, this is a separate discernible response associated to single-pulse TMS over M1. 相似文献13.
John Cirillo John G. Semmler Ronan A. Mooney Winston D. Byblow 《Brain stimulation》2018,11(6):1296-1305
Background
In human primary motor cortex (M1), the paired-pulse transcranial magnetic stimulation (TMS) paradigm of short-interval intracortical inhibition (SICI) can be expressed conventionally as a percent change in the relative amplitude of a conditioned motor evoked potential to non-conditioned; or adaptive threshold-hunting a target motor evoked potential amplitude in the absence or presence of a conditioning stimulus, and noting the relative change in stimulation intensity. The suitability of each approach may depend on the induced current direction, which probe separate M1 interneuronal populations.Objective
To examine the influence of conditioning stimulus intensity, interstimulus interval (ISI) and current direction for adaptive threshold-hunting and conventional SICI using equivalent TMS intensities.Methods
In 16 participants (21–32 years), SICI was examined using adaptive threshold-hunting and conventional paired-pulse TMS with posterior-anterior and anterior-posterior stimulation, ISIs of 2 and 3?ms, and a range of conditioning intensities.Results
Inhibition with adaptive threshold-hunting was greater for anterior-posterior stimulation with an ISI of 3?ms (23.6?±?9.0%) compared with 2?ms (7.5?±?7.8%, P?<?0.001) and posterior-anterior stimulation at both ISIs (2?ms 8.6?±?8.7%, 3?ms 5.9?±?4.8%; P?<?0.001). There was an association between inhibition obtained with conventional and adaptive threshold-hunting for posterior-anterior but not anterior-posterior stimulation (2?ms only, r?=?0.68, P?=?0.03).Conclusions
More inhibition was evident with anterior-posterior than posterior-anterior current for both adaptive threshold-hunting and conventional paired-pulse TMS. Assessment of SICI with anterior-posterior stimulation was not directly comparable between the two approaches. However, the amount of inhibition was dependent on conditioning stimulus intensity and ISI for both SICI techniques. 相似文献14.
Takuya Sasaki Satoshi Kodama Naohiko Togashi Yuichiro Shirota Yusuke Sugiyama Shin-ichi Tokushige Satomi Inomata-Terada Yasuo Terao Yoshikazu Ugawa Masashi Hamada 《Brain stimulation》2018,11(2):400-410
Background
Responses to continuous theta burst stimulation (cTBS) applied to the human primary motor cortex are highly variable between individuals. However, little is known about how to improve the after-effects of cTBS by adjusting the protocol characteristics.Objective
We examined whether current directions adopted in the measurement of cortical motor excitability indexed as motor evoked potentials (MEPs) affect the responses to cTBS. We also tested whether the stimulus intensity of cTBS influences the after-effects.Methods
Thirty-one healthy volunteers participated. The after-effects of cTBS with the conventional intensity of 80% of individual active motor threshold (AMT) (cTBS80%) were tested by measuring MEP amplitudes induced by not only posterior-anterior (PA) but also anterior-posterior (AP) and biphasic (PA-AP) currents. We also investigated cTBS with 65% AMT (cTBS65%) and 100% AMT (cTBS100%) in subjects who showed depression of MEP amplitudes after cTBS80%, as well as cTBS65% in subjects in whom facilitation of MEPs was induced by cTBS80%.Results
Current directions in MEP measurement had no influence on the cTBS responses. In subjects whose MEPs were depressed by cTBS80%, cTBS100% partly induced MEP facilitation, while cTBS65% abolished the after-effects. In subjects who showed MEP facilitation by cTBS80%, cTBS65% partly induced MEP depression.Conclusions
Stimulus intensity of cTBS influenced the responses to cTBS, and lowering stimulus intensity induced the expected after-effects of cTBS in some subjects. 相似文献15.
Background
Deeper short-interval intracortical inhibition (SICI), a marker of GABAA activity, correlates with better motor performance in patients with moderate to severe hand impairments in the chronic phase after stroke.Objectives
We evaluated the correlation between SICI in the affected hemisphere and pinch force of the paretic hand in well-recovered patients. We also investigated the correlation between SICI and pinch force in controls.Methods
Twenty-two subjects were included in the study. SICI was measured with a paired-pulse paradigm. The correlation between lateral pinch strength and SICI was assessed with Spearman's rho.Results
There was a significant correlation (rho?=?0.69, p?=?0.014) between SICI and pinch strength in patients, but not in controls. SICI was significantly deeper in patients with greater hand weakness.Conclusions
These preliminary findings suggest that decreased GABAA activity in M1AH correlates with better hand motor performance in well-recovered subjects with stroke in the chronic phase. 相似文献16.
Natalie Schaworonkow Jochen Triesch Ulf Ziemann Christoph Zrenner 《Brain stimulation》2019,12(1):110-118
Background
Corticospinal excitability depends on the current brain state. The recent development of real-time EEG-triggered transcranial magnetic stimulation (EEG-TMS) allows studying this relationship in a causal fashion. Specifically, it has been shown that corticospinal excitability is higher during the scalp surface negative EEG peak compared to the positive peak of μ-oscillations in sensorimotor cortex, as indexed by larger motor evoked potentials (MEPs) for fixed stimulation intensity.Objective
We further characterize the effect of μ-rhythm phase on the MEP input-output (IO) curve by measuring the degree of excitability modulation across a range of stimulation intensities. We furthermore seek to optimize stimulation parameters to enable discrimination of functionally relevant EEG-defined brain states.Methods
A real-time EEG-TMS system was used to trigger MEPs during instantaneous brain-states corresponding to μ-rhythm surface positive and negative peaks with five different stimulation intensities covering an individually calibrated MEP IO curve in 15 healthy participants.Results
MEP amplitude is modulated by μ-phase across a wide range of stimulation intensities, with larger MEPs at the surface negative peak. The largest relative MEP-modulation was observed for weak intensities, the largest absolute MEP-modulation for intermediate intensities. These results indicate a leftward shift of the MEP IO curve during the μ-rhythm negative peak.Conclusion
The choice of stimulation intensity influences the observed degree of corticospinal excitability modulation by μ-phase. Lower stimulation intensities enable more efficient differentiation of EEG μ-phase-defined brain states. 相似文献17.
Background
Motor imagery and actual movements share overlapping activation of brain areas but little is known about task-specific activation of distinct motor pathways during mental simulation of movements. For real contractions, it was demonstrated that the slow(er) motor pathways are activated differently in ballistic compared to tonic contractions but it is unknown if this also holds true for imagined contractions.Objective
The aim of the present study was to assess the activity of fast and slow(er) motor pathways during mentally simulated movements of ballistic and tonic contractions.Methods
H-reflexes were conditioned with transcranial magnetic stimulation at different interstimulus intervals to assess the excitability of fast and slow(er) motor pathways during a) the execution of tonic and ballistic contractions, b) motor imagery of these contraction types, and c) at rest.Results
In contrast to the fast motor pathways, the slow(er) pathways displayed a task-specific activation: for imagined ballistic as well as real ballistic contractions, the activation was reduced compared to rest whereas enhanced activation was found for imagined tonic and real tonic contractions.Conclusions
This study provides evidence that the excitability of fast and slow(er) motor pathways during motor imagery resembles the activation pattern observed during real contractions. The findings indicate that motor imagery results in task- and pathway-specific subliminal activation of distinct subsets of neurons in the primary motor cortex. 相似文献18.
Elisa Kallioniemi Petri Savolainen Gustaf Järnefelt Päivi Koskenkorva Jari Karhu Petro Julkunen 《Brain stimulation》2018,11(2):322-326
Background
Transcranial magnetic stimulation (TMS) induced I-wave behavior can be demonstrated at neuronal population level using paired-pulses and by observing short-interval cortical facilitation (SICF). Advancements in stimulator technology have made it possible to apply biphasic paired-pulses to induce SICF.Objective
Our aim was to characterize the SICF I-wave interaction by biphasic paired-pulses with the ultimate objective to enhance TMS effects via SICF in various TMS-applications.Methods
We used biphasic paired-pulses in 15 volunteers to characterize corticospinal SICF using various 1.2–8.0ms inter-stimulus intervals, and measuring SICF input-output response.Results
SICF interaction with the first I-wave (I1) was observed in the output responses (motor evoked potentials; MEPs) in all subjects. Most subjects (≥80%) also exhibited later SICF I-wave interaction. SICF at I1 was present at all applied intensities below 140% of resting motor threshold. At I2, we observed SICF only with intensities just above motor threshold.Conclusions
Biphasic paired-pulses can reliably induce SICF shown by the facilitatory I-wave interaction, and could therefore be applied with repetitive bursts to enhance responsiveness to TMS. 相似文献19.
Dalia Khammash Molly Simmonite Thad A. Polk Stephan F. Taylor Sean K. Meehan 《Brain stimulation》2019,12(3):702-704
Background
Transcranial magnetic stimulation (TMS) is a non-invasive method to stimulate localized brain regions. Despite widespread use in motor cortex, TMS is seldom performed in sensory areas due to variable, qualitative metrics.Objective
Assess the reliability and validity of tracing phosphenes, and to investigate the stimulation parameters necessary to elicit decreased visual cortex excitability with paired-pulse TMS at short inter-stimulus intervals.Methods
Across two sessions, single and paired-pulse recruitment curves were derived by having participants outline elicited phosphenes and calculating resulting average phosphene sizes.Results
Phosphene size scaled with stimulus intensity, similar to motor cortex. Paired-pulse recruitment curves demonstrated inhibition at lower conditioning stimulus intensities than observed in motor cortex. Reliability was high across sessions.Conclusions
TMS-induced phosphenes are a valid and reliable tool for measuring cortical excitability and inhibition in early visual areas. Our results also provide appropriate stimulation parameters for measuring short-latency intracortical inhibition in visual cortex. 相似文献20.
Sina Kohl Ricci Hannah Lorenzo Rocchi Camilla L. Nord John Rothwell Valerie Voon 《Neuropsychopharmacology》2019,85(4):355-363