EEG under TMS-induced SP reveals inhibitory effects of low-frequency rTMS on the primary motor cortex

The role of primary motor cortex (M1) in the control of voluntary movements is still unclear. In brain functional imaging studies of unilateral hand performance, bilateral M1 activation is inconsistently observed, and disruptions of M1 using repetitive transcranial magnetic stimulation (rTMS) lead to variable results in the hand motor performance. As the motor tasks differed qualitatively in these studies, it is conceivable that M1 contribution differs depending on the level of skillfulness. The objective of the present study was to determine whether M1 contribution to hand motor performance differed depending on the level of precision of the motor task. Here, we used low-frequency rTMS of left M1 to determine its effect on the performance of a pointing task that allows the parametric increase of the level of precision and thereby increase the level of required precision quantitatively. We found that low-frequency rTMS improved performance in both hands for the task with the highest demand on precision, whereas performance remained unchanged for the tasks with lower demands. These results suggest that the functional relevance of M1 activity for motor performance changes as a function of motor demand. The bilateral effect of rTMS to left M1 would also support the notion of M1 functions at a higher level in motor control by integrating afferent input from nonprimary motor areas.

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Slowing fastest finger movements of the dominant hand with low-frequency rTMS of the hand area of the primary motor cortex

Experimental Brain Research ◽

10.1007/s00221-003-1719-7 ◽

2004 ◽

Vol 155 (2) ◽

pp. 196-203 ◽

Cited By ~ 64

Author(s):

U. Ziemann ◽

L. J�ncke ◽

H. Steinmetz ◽

S. Benilow

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Low Frequency ◽

Dominant Hand ◽

Finger Movements ◽

Hand Area ◽

Low Frequency Rtms

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Bilateral low frequency rTMS of the primary motor cortex may not be a suitable treatment for levodopa-induced dyskinesias in late stage Parkinson's disease

Parkinsonism & Related Disorders ◽

10.1016/j.parkreldis.2015.11.009 ◽

2016 ◽

Vol 22 ◽

pp. 62-67 ◽

Cited By ~ 15

Author(s):

Anja Flamez ◽

Ann Cordenier ◽

Sylvie De Raedt ◽

Véronique Michiels ◽

Sara Smetcoren ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Motor Cortex ◽

Late Stage ◽

Primary Motor Cortex ◽

Low Frequency ◽

Suitable Treatment ◽

Low Frequency Rtms

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Preconditioning with low frequency rTMS over right motor cortex (M1) influences the effect of intermittent Theta Burst Stimulation on excitability over left M1

Klinische Neurophysiologie ◽

10.1055/s-2008-1072843 ◽

2008 ◽

Vol 39 (01) ◽

Author(s):

P Ragert ◽

M Camus ◽

Y Vandermeeren ◽

LG Cohen

Keyword(s):

Motor Cortex ◽

Low Frequency ◽

Theta Burst Stimulation ◽

Burst Stimulation ◽

Theta Burst ◽

Low Frequency Rtms

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Reduced Interhemispheric Coherence in Cerebellar Kainic Acid-Induced Lateralized Dystonia

Frontiers in Neurology ◽

10.3389/fneur.2020.580540 ◽

2020 ◽

Vol 11 ◽

Author(s):

Elena Laura Georgescu Margarint ◽

Ioana Antoaneta Georgescu ◽

Carmen Denise Mihaela Zahiu ◽

Stefan-Alexandru Tirlea ◽

Alexandru Rǎzvan Şteopoaie ◽

...

Keyword(s):

Motor Cortex ◽

Kainic Acid ◽

Primary Motor Cortex ◽

Low Frequency ◽

Muscular Activity ◽

Cerebellar Hemisphere ◽

Interhemispheric Coherence ◽

General Locomotor Activity ◽

Complex Circuits ◽

The Right

The execution of voluntary muscular activity is controlled by the primary motor cortex, together with the cerebellum and basal ganglia. The synchronization of neural activity in the intracortical network is crucial for the regulation of movements. In certain motor diseases, such as dystonia, this synchrony can be altered in any node of the cerebello-cortical network. Questions remain about how the cerebellum influences the motor cortex and interhemispheric communication. This research aims to study the interhemispheric cortical communication between the motor cortices during dystonia, a neurological movement syndrome consisting of sustained or repetitive involuntary muscle contractions. We pharmacologically induced lateralized dystonia to adult male albino mice by administering low doses of kainic acid on the left cerebellar hemisphere. Using electrocorticography and electromyography, we investigated the power spectral densities, cortico-muscular, and interhemispheric coherence between the right and left motor cortices, before and during dystonia, for five consecutive days. Mice displayed lateralized abnormal motor signs, a reduced general locomotor activity, and a high score of dystonia. The results showed a progressive interhemispheric coherence decrease in low-frequency bands (delta, theta, beta) during the first 3 days. The cortico-muscular coherence of the affected side had a significant increase in gamma bands on days 3 and 4. In conclusion, lateralized cerebellar dysfunction during dystonia was associated with a loss of connectivity in the motor cortices, suggesting a possible cortical compensation to the initial disturbances induced by cerebellar left hemisphere kainate activation by blocking the propagation of abnormal oscillations to the healthy hemisphere. However, the cerebellum is part of several overly complex circuits, therefore other mechanisms can still be involved in this phenomenon.

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Chronic low-frequency rTMS of primary motor cortex diminishes exercise training-induced gains in maximal voluntary force in humans

Journal of Applied Physiology ◽

10.1152/japplphysiol.90701.2008 ◽

2009 ◽

Vol 106 (2) ◽

pp. 403-411 ◽

Cited By ~ 20

Author(s):

Tibor Hortobágyi ◽

Sarah Pirio Richardson ◽

Mikhael Lomarev ◽

Ejaz Shamim ◽

Sabine Meunier ◽

...

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Repetitive Transcranial Magnetic Stimulation ◽

Low Frequency ◽

Motor Evoked Potential ◽

Single Pulse ◽

Compound Action Potential ◽

Voluntary Contraction ◽

Maximal Voluntary Force ◽

Resting Motor Threshold

Although there is consensus that the central nervous system mediates the increases in maximal voluntary force (maximal voluntary contraction, MVC) produced by resistance exercise, the involvement of the primary motor cortex (M1) in these processes remains controversial. We hypothesized that 1-Hz repetitive transcranial magnetic stimulation (rTMS) of M1 during resistance training would diminish strength gains. Forty subjects were divided equally into five groups. Subjects voluntarily (Vol) abducted the first dorsal interosseus (FDI) (5 bouts × 10 repetitions, 10 sessions, 4 wk) at 70–80% MVC. Another group also exercised but in the 1-min-long interbout rest intervals they received rTMS [Vol+rTMS, 1 Hz, FDI motor area, 300 pulses/session, 120% of the resting motor threshold (rMT)]. The third group also exercised and received sham rTMS (Vol+Sham). The fourth group received only rTMS (rTMS_only). The 37.5% and 33.3% gains in MVC in Vol and Vol+Sham groups, respectively, were greater ( P = 0.001) than the 18.9% gain in Vol+rTMS, 1.9% in rTMS_only, and 2.6% in unexercised control subjects who received no stimulation. Acutely, within sessions 5 and 10, single-pulse TMS revealed that motor-evoked potential size and recruitment curve slopes were reduced in Vol+rTMS and rTMS_only groups and accumulated to chronic reductions by session 10. There were no changes in rMT, maximum compound action potential amplitude (Mmax), and peripherally evoked twitch forces in the trained FDI and the untrained abductor digiti minimi. Although contributions from spinal sources cannot be excluded, the data suggest that M1 may play a role in mediating neural adaptations to strength training.

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