Reduced Interhemispheric Coherence in Cerebellar Kainic Acid-Induced Lateralized Dystonia

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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Low frequency (0.5Hz) rTMS over the right (non-dominant) motor cortex does not affect ipsilateral hand performance in healthy humans

Arquivos de Neuro-Psiquiatria ◽

10.1590/s0004-282x2008000500006 ◽

2008 ◽

Vol 66 (3b) ◽

pp. 636-640 ◽

Cited By ~ 5

Author(s):

Fernanda Weiler ◽

Pedro Brandão ◽

Jairo de Barros-Filho ◽

Carlos Enrique Uribe ◽

Valdir Filgueiras Pessoa ◽

...

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Repetitive Transcranial Magnetic Stimulation ◽

Hand Function ◽

Motor Task ◽

Low Frequency ◽

Left Hand ◽

Healthy Humans ◽

Hand Performance ◽

The Right

Reduction of excitability of the dominant primary motor cortex (M1) improves ipsilateral hand function in healthy subjects. In analogy, inhibition of non-dominant M1 should also improve ipsilateral performance. In order to investigate this hypothesis, we have used slow repetitive transcranial magnetic stimulation (rTMS) and the Purdue Pegboard test. Twenty-eight volunteers underwent 10 minutes of either 0.5Hz rTMS over right M1 or sham rTMS (coil perpendicular to scalp). The motor task was performed before, immediately after, and 20 minutes after rTMS. In both groups, motor performance improved significantly throughout the sessions. rTMS inhibition of the non-dominant M1 had no significant influence over ipsilateral or contralateral manual dexterity, even though the results were limited by unequal performance between groups at baseline. This is in contrast to an improvement in left hand function previously described following slow rTMS over left M1, and suggests a less prominent physiological transcallosal inhibition from right to left M1.

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Comparison of repeated transcranial stimulation and transcranial direct-current stimulation on primary motor cortex excitability and inhibition: A pilot study

Movement & Sport Sciences - Science & Motricité ◽

10.1051/sm/2018001 ◽

2018 ◽

pp. 59-67 ◽

Cited By ~ 1

Author(s):

Vincent Cabibel ◽

Makii Muthalib ◽

Jérôme Froger ◽

Stéphane Perrey

Keyword(s):

Pilot Study ◽

Motor Cortex ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Primary Motor Cortex ◽

Motor Evoked Potentials ◽

High Definition ◽

Direct Current Stimulation ◽

Motor Cortex Excitability ◽

The Right

Repeated transcranial magnetic stimulation (rTMS) is a well-known clinical neuromodulation technique, but transcranial direct-current stimulation (tDCS) is rapidly growing interest for neurorehabilitation applications. Both methods (contralesional hemisphere inhibitory low-frequency: LF-rTMS or lesional hemisphere excitatory anodal: a-tDCS) have been employed to modify the interhemispheric imbalance following stroke. The aim of this pilot study was to compare aHD-tDCS (anodal high-definition tDCS) of the left M1 (2 mA, 20 min) and LF-rTMS of the right M1 (1 Hz, 20 min) to enhance excitability and reduce inhibition of the left primary motor cortex (M1) in five healthy subjects. Single-pulse TMS was used to elicit resting and active (low level muscle contraction, 5% of maximal electromyographic signal) motor-evoked potentials (MEPs) and cortical silent periods (CSPs) from the right and left extensor carpi radialis muscles at Baseline, immediately and 20 min (Post-Stim-20) after the end of each stimulation protocol. LF-rTMS or aHD-tDCS significantly increased right M1 resting and active MEP amplitude at Post-Stim-20 without any CSP modulation and with no difference between methods. In conclusion, this pilot study reported unexpected M1 excitability changes, which most likely stems from variability, which is a major concern in the field to consider.

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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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Role of the Ipsilateral Motor Cortex in Voluntary Movement

Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques ◽

10.1017/s0317167100032947 ◽

1997 ◽

Vol 24 (04) ◽

pp. 284-291 ◽

Cited By ~ 92

Author(s):

Robert Chen ◽

Leonardo G. Cohen ◽

Mark Hallett

Keyword(s):

Motor Cortex ◽

Functional Recovery ◽

Voluntary Movement ◽

Primary Motor Cortex ◽

Repetitive Transcranial Magnetic Stimulation ◽

Normal Subjects ◽

Older Children ◽

Focal Brain Injury ◽

Complex Sequences ◽

The Right

ABSTRACT:The ipsilateral primary motor cortex (M1) plays a role in voluntary movement. In our studies, we used repetitive transcranial magnetic stimulation (rTMS) to study the effects of transient disruption of the ipsilateral M1 on the performance of finger sequences in right-handed normal subjects. Stimulation of the M1 ipsilateral to the movement induced timing errors in both simple and complex sequences performed with either hand, but with complex sequences, the effects were more pronounced with the left-sided stimulation. Recent studies in both animals and humans have confirmed the traditional view that ipsilateral projections from M1 to the upper limb are mainly directed to truncal and proximal muscles, with little evidence for direct connections to distal muscles. The ipsilateral motor pathway appears to be an important mechanism for functional recovery after focal brain injury during infancy, but its role in functional recovery for older children and adults has not yet been clearly demonstrated. There is increasing evidence from studies using different methodologies such as rTMS, functional imaging and movement-related cortical potentials, that M1 is involved in ipsilateral hand movements, with greater involvement in more complex tasks and the left hemisphere playing a greater role than the right.

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Low-Frequency Oscillations Are a Biomarker of Injury and Recovery After Stroke

Stroke ◽

10.1161/strokeaha.120.028932 ◽

2020 ◽

Vol 51 (5) ◽

pp. 1442-1450 ◽

Cited By ~ 5

Author(s):

Jessica M. Cassidy ◽

Anirudh Wodeyar ◽

Jennifer Wu ◽

Kiranjot Kaur ◽

Ashley K. Masuda ◽

...

Keyword(s):

Primary Motor Cortex ◽

Low Frequency ◽

Inpatient Rehabilitation ◽

Motor Recovery ◽

Rehabilitation Facility ◽

Low Frequency Oscillations ◽

Band Power ◽

Interhemispheric Coherence ◽

Delta Band ◽

Inpatient Rehabilitation Facility

Background and Purpose— Low-frequency oscillations reflect brain injury but also contribute to normal behaviors. We examined hypotheses relating electroencephalography measures, including low-frequency oscillations, to injury and motor recovery poststroke. Methods— Patients with stroke completed structural neuroimaging, a resting-state electroencephalography recording and clinical testing. A subset admitted to an inpatient rehabilitation facility also underwent serial electroencephalography recordings. The relationship that electroencephalography measures (power and coherence with leads overlying ipsilesional primary motor cortex [iM1]) had with injury and motor status was assessed, focusing on delta (1–3 Hz) and high-beta (20–30 Hz) bands. Results— Across all patients (n=62), larger infarct volume was related to higher delta band power in bilateral hemispheres and to higher delta band coherence between iM1 and bilateral regions. In chronic stroke, higher delta power bilaterally correlated with better motor status. In subacute stroke, higher delta coherence between iM1 and bilateral areas correlated with poorer motor status. These coherence findings were confirmed in serial recordings from 18 patients in an inpatient rehabilitation facility. Here, interhemispheric coherence between leads overlying iM1 and contralesional M1 was elevated at inpatient rehabilitation facility admission compared with healthy controls (n=22), declining to control levels over time. Decreases in interhemispheric coherence between iM1 and contralesional M1 correlated with better motor recovery. Conclusions— Delta band coherence with iM1 related to greater injury and poorer motor status subacutely, while delta band power related to greater injury and better motor status chronically. Low-frequency oscillations reflect both injury and recovery after stroke and may be useful biomarkers in stroke recovery and rehabilitation.

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

Brain Stimulation ◽

10.1016/j.brs.2017.01.096 ◽

2017 ◽

Vol 10 (2) ◽

pp. 372 ◽

Cited By ~ 1

Author(s):

F. Jin ◽

J. Jin ◽

Y. Li ◽

X. Wang ◽

Z. Liu ◽

...

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Low Frequency ◽

Inhibitory Effects ◽

Low Frequency Rtms

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Inhibition of the primary motor cortex can alter one's “sense of effort”: Effects of low-frequency rTMS

Neuroscience Research ◽

10.1016/j.neures.2014.09.005 ◽

2014 ◽

Vol 89 ◽

pp. 54-60 ◽

Cited By ~ 20

Author(s):

Yudai Takarada ◽

Tatsuya Mima ◽

Mitsunari Abe ◽

Masahiro Nakatsuka ◽

Masato Taira

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Low Frequency ◽

Sense Of Effort ◽

Low Frequency Rtms

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Cognitive control affects motor learning through local variations in GABA within the primary motor cortex

Scientific Reports ◽

10.1038/s41598-021-97974-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Shuki Maruyama ◽

Masaki Fukunaga ◽

Sho K. Sugawara ◽

Yuki H. Hamano ◽

Tetsuya Yamamoto ◽

...

Keyword(s):

Magnetic Resonance ◽

Motor Cortex ◽

Motor Learning ◽

Cognitive Control ◽

Primary Motor Cortex ◽

Resonance Spectroscopy ◽

Motor Sequence ◽

Sensorimotor Network ◽

Preparatory Activity ◽

The Right

AbstractThe primary motor cortex (M1) is crucial for motor learning; however, its interaction with other brain areas during motor learning remains unclear. We hypothesized that the fronto-parietal execution network (FPN) provides learning-related information critical for the flexible cognitive control that is required for practice. We assessed network-level changes during sequential finger tapping learning under speed pressure by combining magnetic resonance spectroscopy and task and resting-state functional magnetic resonance imaging. There was a motor learning-related increase in preparatory activity in the fronto-parietal regions, including the right M1, overlapping the FPN and sensorimotor network (SMN). Learning-related increases in M1-seeded functional connectivity with the FPN, but not the SMN, were associated with decreased GABA/glutamate ratio in the M1, which were more prominent in the parietal than the frontal region. A decrease in the GABA/glutamate ratio in the right M1 was positively correlated with improvements in task performance (p = 0.042). Our findings indicate that motor learning driven by cognitive control is associated with local variations in the GABA/glutamate ratio in the M1 that reflects remote connectivity with the FPN, representing network-level motor sequence learning formations.

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Cortical Representations of Transversus Abdominis and Multifidus Muscles Were Discrete in Patients with Chronic Low Back Pain: Evidence Elicited by TMS

Neural Plasticity ◽

10.1155/2021/6666024 ◽

2021 ◽

Vol 2021 ◽

pp. 1-9

Author(s):

Xin Li ◽

Howe Liu ◽

Le Ge ◽

Yifeng Yan ◽

Wai Leung Ambrose Lo ◽

...

Keyword(s):

Back Pain ◽

Motor Cortex ◽

Primary Motor Cortex ◽

Strong Support ◽

Transversus Abdominis ◽

Chronic Lower Back Pain ◽

Healthy Individuals ◽

Neural Basis ◽

Healthy Group ◽

The Right

Introduction. The transversus abdominis (TVA) and multifidus (MF) muscles are the main segmental spinal stabilizers that are controlled by the primary motor cortex of the brain. However, relocations of the muscle representation in the motor cortex may occur after chronic lower back pain (cLBP); it still needs more evidence to be proven. The current study was aimed at applying transcranial magnetic stimulation (TMS) to investigate the changes of representation of TVA and MF muscles at the cortical network in individuals with cLBP. Methods. Twenty-four patients with cLBP and 12 age-matched healthy individuals were recruited. Responses of TVA and MF to TMS during muscle contraction were monitored and mapped over the contralateral cortex using a standardized grid cap. Maps of the center of gravity (CoG), area, volume, and latency were analyzed, and the asymmetry index was also computed and compared. Results. The locations of MF CoG in cLBP individuals were posterior and lateral to the CoG locations in healthy individuals. In the healthy group, the locations of TVA and MF CoG were closed to each other in both the left and right hemispheres. In the cLBP group, these two locations were next to each other in the right hemisphere but discrete in the left hemisphere. In the cLBP group, the cortical motor map of TVA and MF were mutually symmetric in five out of eleven (45.5%) subjects and leftward asymmetric in four out of ten (40.0%) subjects. Conclusions. Neural representations of TVA and MF muscles were closely organized in both the right and left motor cortices in the healthy group but were discretely organized in the left motor cortex in the cLBP group. This provides strong support for the neural basis of pathokinesiology and clinical treatment of cLBP.

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Cutaneous Inputs Can Activate the Ipsilateral Primary Motor Cortex During Bimanual Sensory-Driven Movements in Humans

Journal of Neurophysiology ◽

10.1152/jn.00937.2003 ◽

2004 ◽

Vol 92 (6) ◽

pp. 3200-3209 ◽

Cited By ~ 7

Author(s):

Satoshi Shibuya ◽

Yukari Ohki

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Cortical Excitability ◽

Human Subjects ◽

Random Sequence ◽

Virtual Object ◽

Active Motor ◽

Finger Forces ◽

The Right ◽

Transient Force

Using transcranial magnetic stimulation (TMS), we examined whether sensory input from a finger affects activity of the ipsilateral primary motor cortex (M1) when human subjects hold a virtual object bimanually and whether this ipsilateral activation varies under different contexts. Subjects used both index fingers to hold two plates, which were subjected to unpredictable pulling loads from torque motors. Loads were delivered in a random sequence to either plate or concurrently to both, although the latter occurred most frequently. Finger forces vertical to the plates and surface electromyographs from the first dorsal interosseous muscles were recorded bilaterally during the task. TMS was sometimes applied over the finger area of the left M1 at variable times relative to load onset to examine cortical excitability. Strength of TMS was set around the active motor threshold of the right finger muscle while subjects waited for loading to the handheld plates. When one plate was singly loaded, the M1 contralateral to the loaded finger was activated, causing automatic force increases in the finger. In addition, the ipsilateral M1 was activated during such loading, associated with transient force increases in the contralateral nonloaded finger. Activations in the ipsilateral M1 were also observed during concurrent loading, when activations were stronger than those following single loading of the contralateral plate. Ipsilateral activations weakened when concurrent loading was less frequent. These results suggest interactions between bilateral sensorimotor cortices during bimanual coordinated movements, with strength varying by context.

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