Intracortical Inhibition and Surround Inhibition in the Motor Cortex: A TMS-EEG Study

Leodori, Giorgio; Thirugnanasambandam, Nivethida; Conn, Hannah; Popa, Traian; Berardelli, Alfredo; Hallett, Mark

doi:10.3389/fnins.2019.00612

Cited by 34 publications

(23 citation statements)

References 60 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The intensity of QPS was set at 90% AMT and was 40.8 ± 7.0 (mean ± SD) % of the maximum stimulator output. We did not use QPS with an ISI of 5 msec (excitatory QPS) because it is well known that facilitation is often associated with surround inhibition [54, 55]. It is well established that the inhibitory QPS reduces MEP by approximately 50% for approximately 90 min [45, 46].…”

Section: Methodsmentioning

confidence: 99%

MRI-based visualization of rTMS-induced cortical plasticity in the primary motor cortex

et al. 2019

View full text Add to dashboard Cite

Repetitive transcranial magnetic stimulation (rTMS) induces changes in cortical excitability for minutes to hours after the end of intervention. However, it has not been precisely determined to what extent cortical plasticity prevails spatially in the cortex. Recent studies have shown that rTMS induces changes in “interhemispheric” functional connectivity, the resting-state functional connectivity between the stimulated region and the symmetrically corresponding region in the contralateral hemisphere. In the present study, quadripulse stimulation (QPS) was applied to the index finger representation in the left primary motor cortex (M1), while the position of the stimulation coil was constantly monitored by an online navigator. After QPS application, resting-state functional magnetic resonance imaging was performed, and the interhemispheric functional connectivity was compared with that before QPS. A cluster of connectivity changes was observed in the stimulated region in the central sulcus. The cluster was spatially extended approximately 10 mm from the center [half width at half maximum (HWHM): approximately 3 mm] and was extended approximately 20 mm long in depth (HWHM: approximately 7 mm). A localizer scan of the index finger motion confirmed that the cluster of interhemispheric connectivity changes overlapped spatially with the activation related to the index finger motion. These results indicate that cortical plasticity in M1 induced by rTMS was relatively restricted in space and suggest that rTMS can reveal functional dissociation associated with adjacent small areas by inducing neural plasticity in restricted cortical regions.

show abstract

Section: Methodsmentioning

confidence: 99%

MRI-based visualization of rTMS-induced cortical plasticity in the primary motor cortex

et al. 2019

View full text Add to dashboard Cite

show abstract

“…The motor hotspot for ADM was identified as the one that elicited largest motor-evoked potentials (MEP) consistently. The coil was positioned over the hotspot to deliver a postero-anteriorly directed current in the brain [5]. MEP recruitment curve was plotted as described in previous studies to identify the S50 (intensity that elicits MEP whose amplitude is 50% of the maximum) [5,14].…”

Section: Methodsmentioning

confidence: 99%

“…The coil was positioned over the hotspot to deliver a postero-anteriorly directed current in the brain [5]. MEP recruitment curve was plotted as described in previous studies to identify the S50 (intensity that elicits MEP whose amplitude is 50% of the maximum) [5,14]. Resting motor threshold (RMT) was estimated using adaptive threshold hunting procedure [15].…”

Section: Methodsmentioning

confidence: 99%

“…Mean test MEP amplitude at rest mSI was estimated using the conventional paradigm [5,16] where subjects performed an auditory-cued brief index finger flexion task with a self-paced delay and suprathreshold pulses were delivered over the ADM hotspot either at rest or at movement onset. A repeated-measures ANOVA was performed with muscle (2 levels: FDI/ADM) and condition (4 levels: test/mSI/PMI/PM-SI) as independent factors, and normalized peak-to-peak MEP amplitude as dependent variable.…”

Section: Mean Conditioned Mep Amplitude At Restmentioning

confidence: 99%

“…mSI is thought to be mediated by intracortical inhibitory mechanisms since patients with focal hand dystonia (FHD) who exhibited reduced mSI also had less short-latency intracortical inhibition (SICI), a phenomenon mediated by GABAa intracortical networks [2e4]. Concurrent transcranial magnetic stimulation (TMS) and electroencephalography studies also suggest that both mSI and SICI may be mediated by intracortical motor networks [5]. Dual-site TMS has been used to elucidate the role of ipsilateral dorsal and ventral premotor [6,7], and contralateral primary motor cortices in the genesis of mSI, but without success.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Parietal conditioning enhances motor surround inhibition

et al. 2020

Self Cite

View full text Add to dashboard Cite

Background: Motor surround inhibition (mSI) is a phenomenon supportive for executing selective finger movements, wherein synergist muscles are selectively facilitated while surround muscles are inhibited. Previous studies of conditioning inputs to several intracortical and cortico-cortical inhibitory networks did not show an influence on mSI. The inhibitory posterior parietal-motor network, which is crucial for executing fine movements, however, has not been studied. Objective/hypothesis: To investigate the role of inhibitory posterior parietal-motor network in mSI. We hypothesized that conditioning this inhibitory network would enhance mSI. Methods: 11 healthy adults completed study. mSI was elicited by applying a TMS pulse over the motor cortex coupled with or without a conditioning input to an inhibitory spot in the posterior parietal cortex at 2 or 4 ms interval. Results: Conditioning input to the posterior parietal cortex increased mSI by~20% Conclusion: The inhibitory posterior parietal-motor network appears to contribute to the genesis of mSI.

show abstract

Re‐emergent Tremor in Parkinson's Disease: The Role of the Motor Cortex

et al. 2020

Self Cite

View full text Add to dashboard Cite

Background: Parkinson's disease patients may show a tremor that appears after a variable delay while the arms are kept outstretched (re-emergent tremor). The objectives of this study were to investigate re-emergent tremor pathophysiology by studying the role of the primary motor cortex in this tremor and making a comparison with rest tremor. Methods:We enrolled 10 Parkinson's disease patients with both re-emergent and rest tremor. Tremor was assessed by spectral analysis, corticomuscular coherence and tremor-resetting produced by transcranial magnetic stimulation over the primary motor cortex. We also recorded transcranial magnetic stimulation-evoked potentials generated by motor cortex stimulation during rest tremor, tremor suppression during wrist extension, and re-emergent tremor. Spectral analysis, corticomuscular coherence, and tremor resetting were compared between re-emergent tremor and rest tremor.Results: Re-emergent tremor showed significant corticomuscular coherence, causal relation between motor cortex activity and tremor muscle and tremor resetting. The P60 component of transcranial magnetic stimulation-evoked potentials reduced in amplitude during tremor suppression, recovered before re-emergent tremor, was facilitated at re-emergent tremor onset, and returned to values similar to those of rest tremor during re-emergent tremor. Compared with rest tremor, re-emergent tremor showed similar corticomuscular coherence and tremor resetting, but slightly higher frequency. Conclusions:Re-emergent tremor is causally related with the activity of the primary motor cortex, which is likely a convergence node in the network that generates re-emergent tremor.

show abstract

Intracortical Inhibition and Surround Inhibition in the Motor Cortex: A TMS-EEG Study

Cited by 34 publications

References 60 publications

MRI-based visualization of rTMS-induced cortical plasticity in the primary motor cortex

MRI-based visualization of rTMS-induced cortical plasticity in the primary motor cortex

Parietal conditioning enhances motor surround inhibition

Re‐emergent Tremor in Parkinson's Disease: The Role of the Motor Cortex

Contact Info

Product

Resources

About