Reduced cortical excitability in depression

1999 ◽  
Vol 174 (5) ◽  
pp. 449-454 ◽  
Author(s):  
P. M. Shajahan ◽  
M. F. Glabus ◽  
P. A. Gooding ◽  
P. J. Shah ◽  
K. P. Ebmeier
Keyword(s):  
Magnetic Stimulation ◽  
Evoked Potential ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potential ◽  
Abductor Pollicis Brevis ◽  
Post Exercise ◽  
Significant Difference ◽  
Dsm Iv ◽  
The Mean

BackgroundIn healthy controls, preactivation of muscles by exercise results in enhanced motor-evoked potential (MEP) responses to transcranial magnetic stimulation (TMS).AimsWe tested the hypothesis that medicated, depressed patients would show reduced post-exercise MEP facilitation compared with controls.MethodTen patients with DSM-IV depression (two male, eight female) and ten controls (three male, seven female) participated. MEPs were elicited at rest, then after exercising the contralateral abductor pollicis brevis muscle, using TMS of the primary motor cortex.ResultsThe mean MEP amplitude recorded after exercise (expressed as a percentage of baseline) was 210% in controls and 130% in patients. There was a significant difference in post-exercise MEP between patients and controls (P=0.03).ConclusionsPost-exercise MEP facilitation was demonstrated in controls but not in patients. This supports the hypothesis that the modulation of cortical excitability may be impaired in depression.

Direct corticospinal pathways contribute to neuromuscular control of perturbed stance

2006 ◽  
Vol 101 (2) ◽  
pp. 420-429 ◽  
Author(s):  
Wolfgang Taube ◽  
Martin Schubert ◽  
Markus Gruber ◽  
Sandra Beck ◽  
Michael Faist ◽  
...  
Keyword(s):  
Magnetic Stimulation ◽  
Evoked Potential ◽  
Cortical Excitability ◽  
Motor Evoked Potential ◽  
Neuromuscular Control ◽  
H Reflex ◽  
Compensatory Response ◽  
Long Latency Responses ◽  
Long Latency ◽  
Posterior Translation

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.

Cortical Excitability of Psychiatric Disorders: Reduced Post-Exercise Facilitation in Depression Compared to Schizophrenia and Controls

2002 ◽  
Vol 36 (5) ◽  
pp. 669-673 ◽  
Author(s):  
Philip D. Reid ◽  
Brett Daniels ◽  
Marzena Rybak ◽  
Yvonne Turnier-Shea ◽  
Saxby Pridmore
Keyword(s):  
Motor Cortex ◽  
Depressive Episode ◽  
Major Depressive Episode ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Control Group ◽  
Major Depressive ◽  
Abductor Pollicis Brevis ◽  
Post Exercise

Objective: In normal subjects, motor evoked potentials (MEPs) produced by transcranial magnetic stimulation (TMS) from the motor cortex are increased after non-fatiguing exercise of hand muscles. This phenomenon is called post-exercise facilitation. This study aims to test the hypothesis that psychiatric syndromes (major depressive episode, schizophrenia) have different levels of post-exercise facilitation compared to controls. Methods: Patients with DSM-IV major depressive episode (six female, four male), schizophrenia (two female, nine male) and a control group (nine female, four male) participated. MEPs were elicited pre- and post-exercise from the contralateral abductor pollicis brevis by TMS over the primary motor cortex. Results: Post-exercise facilitation expressed as a percentage of baseline was 510% in controls, 110% in depression and 190% in schizophrenia. There were significant differences in patients with depression and schizophrenia compared to controls (p = 0.0001, p = 0.0008). Conclusions: Post-exercise facilitation was reduced in depression and schizophrenia, suggesting impaired cortical excitability in these disorders. Further studies may discriminate between the two groups.

scholarly journals Effects of transcranial static magnetic stimulation over the primary motor cortex on local and network spontaneous electroencephalogram oscillations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sumiya Shibata ◽  
Tatsunori Watanabe ◽  
Yoshihiro Yukawa ◽  
Masatoshi Minakuchi ◽  
Ryota Shimomura ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Power Spectrum ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Controlled Study ◽  
Functional Coupling ◽  
Phase Lag ◽  
Theta Band ◽  
Double Blind

AbstractTranscranial static magnetic stimulation (tSMS) is a novel non-invasive brain stimulation technique that reduces cortical excitability at the stimulation site. We investigated the effects of tSMS over the left primary motor cortex (M1) for 20 min on the local electroencephalogram (EEG) power spectrum and interregional EEG coupling. Twelve right-handed healthy subjects participated in this crossover, double-blind, sham-controlled study. Resting-state EEG data were recorded for 3 min before the intervention and 17 min after the beginning of the intervention. The power spectrum at the left central electrode (C3) and the weighted phase lag index (wPLI) between C3 and the other electrodes was calculated for theta (4–8 Hz), alpha (8–12 Hz), and beta (12–30 Hz) frequencies. The tSMS significantly increased theta power at C3 and the functional coupling in the theta band between C3 and the parietal midline electrodes. The tSMS over the left M1 for 20 min exhibited modulatory effects on local cortical activity and interregional functional coupling in the theta band. The neural oscillations in the theta band may have an important role in the neurophysiological effects induced by tSMS over the frontal cortex.

scholarly journals Demand on skillfulness modulates interhemispheric inhibition of motor cortices

2016 ◽  
Vol 115 (6) ◽  
pp. 2803-2813 ◽  
Author(s):  
Miles Wischnewski ◽  
Greg M. Kowalski ◽  
Farrah Rink ◽  
Samir R. Belagaje ◽  
Marc W. Haut ◽  
...  
Keyword(s):  
Primary Motor Cortex ◽  
Motor Task ◽  
Conditioning Stimulus ◽  
Motor Evoked Potential ◽  
Inhibitory Effect ◽  
Left Hand ◽  
The Mean ◽  
Small Targets ◽  
Healthy Participants

The role of primary motor cortex (M1) in the control of hand movements is still unclear. Functional magnetic resonance imaging (fMRI) studies of unimanual performance reported a relationship between level of precision of a motor task and additional ipsilateral M1 (iM1) activation. In the present study, we determined whether the demand on accuracy of a movement influences the magnitude of the inhibitory effect between primary motor cortices (IHI). We used transcranial magnetic stimulation (TMS) to measure active IHI (aIHI) of the iM1 on the contralateral M1 (cM1) in the premovement period of a left-hand motor task. Ten healthy participants manipulated a joystick to point to targets of two different sizes. For aIHI, the conditioning stimulus (CS) was applied to iM1, and the test stimulus (TS) to cM1, with an interstimulus interval of 10 ms. The amount of the inhibitory effect of the CS on the motor-evoked potential (MEP) of the subsequent TS was expressed as percentage of the mean MEP amplitude evoked by the single TS. Across different time points of aIHI measurements in the premovement period, there was a significant effect for target size on aIHI. Preparing to point to small targets was associated with weaker aIHI compared with pointing to large targets. The present findings suggest that, during the premovement period, aIHI from iM1 on cM1 is modulated by the demand on accuracy of the motor task. This is consistent with task fMRI findings showing bilateral M1 activation during high-precision movements but only unilateral M1 activity during low-precision movements.

scholarly journals Modulation of the Corticomotor Excitability by Repetitive Peripheral Magnetic Stimulation on the Median Nerve in Healthy Subjects

2021 ◽  
Vol 15 ◽  
Author(s):  
Yanbing Jia ◽  
Xiaoyan Liu ◽  
Jing Wei ◽  
Duo Li ◽  
Chun Wang ◽  
...  
Keyword(s):  
Peripheral Nerve ◽  
Healthy Subjects ◽  
Magnetic Stimulation ◽  
Evoked Potential ◽  
Sham Group ◽  
Motor Evoked Potential ◽  
Dominant Hand ◽  
Corticomotor Excitability ◽  
Hand Dexterity ◽  
Stimulation Group

Objective: We aimed to examine the effects of repetitive peripheral nerve magnetic stimulation (rPNMS) on the excitability of the contralateral motor cortex and motor function of the upper limb in healthy subjects.Methods: Forty-six healthy subjects were randomly assigned to either a repetitive peripheral nerve magnetic stimulation group (n = 23) or a sham group (n = 23). The repetitive peripheral nerve magnetic stimulation group received stimulation using magnetic pulses at 20 Hz, which were applied on the median nerve of the non-dominant hand, whereas the sham group underwent the same protocol without the stimulation output. The primary outcome was contralateral transcranial magnetic stimulation (TMS)-induced corticomotor excitability for the abductor pollicis brevis of the stimulated hand in terms of resting motor threshold (rMT), the slope of recruitment curve, and peak amplitude of motor evoked potential (MEP), which were measured at baseline and immediately after each session. The secondary outcomes were motor hand function including dexterity and grip strength of the non-dominant hand assessed at baseline, immediately after stimulation, and 24 h post-stimulation.Results: Compared with the sham stimulation, repetitive peripheral nerve magnetic stimulation increased the peak motor evoked potential amplitude immediately after the intervention. The repetitive peripheral nerve magnetic stimulation also increased the slope of the recruitment curve immediately after intervention and enhanced hand dexterity after 24 h. However, the between-group difference for the changes was not significant. The significant changes in hand dexterity and peak amplitude of motor evoked potential after repetitive peripheral nerve magnetic stimulation were associated with their baseline value.Conclusions: Repetitive peripheral nerve magnetic stimulation may modulate the corticomotor excitability together with a possible lasting improvement in hand dexterity, indicating that it might be helpful for clinical rehabilitation.

Low-Threshold Monopolar Motor Mapping for Resection of Primary Motor Cortex Tumors

2012 ◽  
Vol 71 (suppl_1) ◽  
pp. ons104-ons115 ◽  
Author(s):  
Kathleen Seidel ◽  
Jürgen Beck ◽  
Lennart Stieglitz ◽  
Philippe Schucht ◽  
Andreas Raabe
Keyword(s):  
Motor Neurons ◽  
Evoked Potential ◽  
Primary Motor Cortex ◽  
Motor Evoked Potential ◽  
National Institutes Of Health ◽  
Motor Deficit ◽  
Motor Threshold ◽  
Motor Mapping ◽  
Low Threshold ◽  
A Minor

Abstract BACKGROUND: Microsurgery within eloquent cortex is a controversial approach because of the high risk of permanent neurological deficit. Few data exist showing the relationship between the mapping stimulation intensity required for eliciting a muscle motor evoked potential and the distance to the motor neurons; furthermore, the motor threshold at which no deficit occurs remains to be defined. OBJECTIVE: To evaluate the safety of low threshold motor evoked potential mapping for tumor resection close to the primary motor cortex. METHODS: Fourteen patients undergoing tumor surgery were included. Motor threshold was defined as the stimulation intensity that elicited motor evoked potentials from target muscles (amplitude &gt; 30 μV). Monopolar high-frequency motor mapping with train-of-5 stimuli (HF-TOF; pulse duration = 500 microseconds; interstimulus interval = 4.0 milliseconds; frequency = 250 Hz) was used to determine motor response--negative sites where incision and dissection could be performed. At sites negative to 3-mA HF-TOF stimulation, the tumor was resected. RESULTS: HF-TOF mapping localized the motor neurons within the precentral gyrus by using variable, low-stimulation intensities. The lowest motor thresholds after final resection ranged from 3 to 6 mA, indicating close proximity of motor neurons. Postoperatively, 12 patients had no new motor deficit, 1 patient had a minor new temporary deficit (M4+, National Institutes of Health Stroke Scale 1), and another patient had a minor new permanent deficit (M4+, National Institutes of Health Stroke Scale 2). Thirteen patients had complete or gross total resection. CONCLUSION: These preliminary data demonstrate that a monopolar HF-TOF threshold &gt; 3 mA was not associated with a significant new motor deficit.

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