Motor control: spinal and cortical mechanisms

2016 ◽  
Author(s):  
David Burke
Keyword(s):  
Motor Control ◽  
Motor Cortex ◽  
Voluntary Movement ◽  
Primary Motor Cortex ◽  
Lower Limbs ◽  
Spinal Reflex ◽  
Extensive Literature ◽  
Spinal Level ◽  
Corticospinal System ◽  
The Brain

There is extensive machinery at cerebral and spinal levels to support voluntary movement, but spinal mechanisms are often ignored by clinicians and researchers. For movements of the upper and lower limbs, what the brain commands can be modified or even suppressed completely at spinal level. The corticospinal system is the executive pathway for movement arising largely from primary motor cortex, but movement is not initiated there, and other pathways normally contribute to movement. Greater use of these pathways can allow movement to be restored when the corticospinal system is damaged by, e.g. stroke, but there can be unwanted consequences of this ‘plasticity’. There is an extensive literature on cerebral mechanisms in the control of movement, and an equally large literature on spinal reflex function and the changes that occur during movement, and when pathology results in weakness and/or spasticity.

Functional reorganization oF the primary motor cortex in a patient with a large arteriovenous malFormation involving the precentral gyrus

2013 ◽  
Vol 4 (2) ◽  
Author(s):  
Milan Radoš ◽  
Ines Nikić ◽  
Marko Radoš ◽  
Ivica Kostović ◽  
Patrick Hof ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Right Hemisphere ◽  
Motor Area ◽  
Lower Limbs ◽  
Motor Deficits ◽  
Precentral Gyrus ◽  
Functional Reorganization ◽  
The Right ◽  
The Brain

AbstractIt is known that the brain can compensate for deficits induced by acquired and developmental lesions through functional reorganization of the remaining parenchyma. Arteriovenous malformations (AVM) usually appear prenatally before a functional regional organization of the brain is fully established and patients generally do not present with motor deficits even when the AVM is located in the primary motor area indicating the redistribution of functions in cortical areas that are not pathologically altered. Here we present reorganization of the motor cortex in a patient with a large AVM involving most of the left parietal lobe and the paramedian part of the left precentral gyrus that is responsible for controlling the muscles of the lower limbs. Functional MRI showed that movements of both the right and left feet activated only the primary motor cortex in the right hemisphere, while there was no activation in the left motor cortex. This suggests that complete ipsilateral control over the movements of the right foot had been established in this patient. A reconstruction of the corticospinal tract using diffusion tensor imaging showed a near-complete absence of corticospinal fibers from the part of the left precentral gyrus affected by the AVM. From this clinical presentation it can be concluded that full compensation of motor deficits had occurred by redistributing function to the corresponding motor area of the contralateral

Long range high-gamma (60-90 Hz) coupling between primary motor cortex and SMA during motor control revealed by MEG source imaging

NeuroImage ◽  
2009 ◽  
Vol 47 ◽  
pp. S173
Author(s):  
K Jerbi ◽  
H Hui ◽  
D Pantazis ◽  
J-P Lachaux ◽  
O Bertrand ◽  
...  
Keyword(s):  
Motor Control ◽  
Motor Cortex ◽  
Long Range ◽  
Primary Motor Cortex ◽  
Source Imaging ◽  
High Gamma

scholarly journals Role of the Ipsilateral Motor Cortex in Voluntary Movement

1997 ◽  
Vol 24 (04) ◽  
pp. 284-291 ◽  
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.

Functional Properties of Human Primary Motor Cortex Gamma Oscillations

2010 ◽  
Vol 104 (5) ◽  
pp. 2873-2885 ◽  
Author(s):  
Suresh D. Muthukumaraswamy
Keyword(s):  
Motor Control ◽  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Gamma Oscillations ◽  
Finger Movement ◽  
Sensorimotor System ◽  
Repetitive Movement ◽  
Somatosensory Feedback ◽  
Muscle Shortening ◽  
Kinematic Properties

Gamma oscillations in human primary motor cortex (M1) have been described in human electrocorticographic and noninvasive magnetoencephalographic (MEG)/electroencephalographic recordings, yet their functional significance within the sensorimotor system remains unknown. In a set of four MEG experiments described here a number of properties of these oscillations are elucidated. First, gamma oscillations were reliably localized by MEG in M1 and reached peak amplitude 137 ms after electromyographic onset and were not affected by whether movements were cued or self-paced. Gamma oscillations were found to be stronger for larger movements but were absent during the sustained part of isometric movements, with no finger movement or muscle shortening. During repetitive movement sequences gamma oscillations were greater for the first movement of a sequence. Finally, gamma oscillations were absent during passive shortening of the finger compared with active contractions sharing similar kinematic properties demonstrating that M1 oscillations are not simply related to somatosensory feedback. This combined pattern of results is consistent with gamma oscillations playing a role in a relatively late stage of motor control, encoding information related to limb movement rather than to muscle contraction.

Effects on Muscle Activity From Microstimuli Applied to Somatosensory and Motor Cortex During Voluntary Movement in the Monkey

1997 ◽  
Vol 77 (5) ◽  
pp. 2446-2465 ◽  
Author(s):  
Gail L. Widener ◽  
Paul D. Cheney
Keyword(s):  
Motor Cortex ◽  
Muscle Activity ◽  
Voluntary Movement ◽  
Primary Motor Cortex ◽  
Large Fraction ◽  
Single Pulse ◽  
Motor Output ◽  
Emg Activity ◽  
Spike Triggered Averaging ◽  
Area 3A

Widener, Gail L. and Paul D. Cheney. Effects on muscle activity from microstimuli applied to somatosensory and motor cortex during voluntary movement in the monkey. J. Neurophysiol. 77: 2446–2465, 1997. It is well known that electrical stimulation of primary somatosensory cortex (SI) evokes movements that resemble those evoked from primary motor cortex. These findings have led to the concept that SI may possess motor capabilities paralleling those of motor cortex and speculation that SI could function as a robust relay mediating motor responses from central and peripheral inputs. The purpose of this study was to rigorously examine the motor output capabilities of SI areas with the use of the techniques of spike- and stimulus-triggered averaging of electromyographic (EMG) activity in awake monkeys. Unit recordings were obtained from primary motor cortex and SI areas 3a, 3b, 1, and 2 in three rhesus monkeys. Spike-triggered averaging was used to assess the output linkage between individual cells and motoneurons of the recorded muscles. Cells in motor cortex producing postspike facilitation (PSpF) in spike-triggered averages of rectified EMG activity were designated corticomotoneuronal (CM) cells. Motor output efficacy was also assessed by applying stimuli through the microelectrode and computing stimulus-triggered averages of rectified EMG activity. One hundred seventy-one sites in motor cortex and 68 sites in SI were characterized functionally and tested for motor output effects on muscle activity. The incidence, character, and magnitude of motor output effects from SI areas were in sharp contrast to effects from CM cell sites in primary motor cortex. Of 68 SI cells tested with spike-triggered averaging, only one area 3a cell produced significant PSpF in spike-triggered averages of EMG activity. In comparison, 20 of 171 (12%) motor cortex cells tested produced significant postspike effects. Single-pulse intracortical microstimulation produced effects at all CM cell sites in motor cortex but at only 14% of SI sites. The large fraction of SI effects that was inhibitory represented yet another marked difference between CM cell sites in motor cortex and SI sites (25% vs 93%). The fact that motor output effects from SI were frequently absent or very weak and predominantly inhibitory emphasizes the differing motor capabilities of SI compared with primary motor cortex.

scholarly journals Electrode Placement in Transcranial Direct Current Stimulation—How Reliable Is the Determination of C3/C4?

2019 ◽  
Vol 9 (3) ◽  
pp. 69 ◽  
Author(s):  
Tonya Rich ◽  
Bernadette Gillick
Keyword(s):  
Motor Cortex ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Primary Motor Cortex ◽  
Electrode Placement ◽  
Rater Reliability ◽  
Direct Current Stimulation ◽  
Adult Participants ◽  
The Brain ◽  
Absolute Reliability

The 10/20 electroencephalogram (EEG) measurements system often guides electrode placement for transcranial direct current stimulation (tDCS), a form of non-invasive brain stimulation. One targeted region of the brain is the primary motor cortex (M1) for motor recovery after stroke, among other clinical indications. M1 is identified by C3 and C4 of the 10/20 EEG system yet the reliability of 10/20 EEG measurements by novice research raters is unknown. We investigated the reliability of the 10/20 EEG measurements for C3 and C4 in 25 adult participants. Two novice raters were assessed for inter-rater reliability. Both raters received two hours of instruction from a registered neurodiagnostic technician. One of the raters completed the measurements across two testing days for intra-rater reliability. Relative reliability was determined using the intraclass coefficient (ICC) and absolute reliability. We observed a low to fair inter and intra-rater ICC for motor cortex measurements. The absolute reliability was <1.0 cm by different novice raters and on different days. Although a low error was observed, consideration of the integrity of the targeted region of the brain is critical when designing tDCS interventions in clinical populations who may have compromised brain structure, due to a lesion or altered anatomy.

Improvement of spasticity following intermittent theta burst stimulation in multiple sclerosis is associated with modulation of resting-state functional connectivity of the primary motor cortices

2016 ◽  
Vol 23 (6) ◽  
pp. 855-863 ◽  
Author(s):  
Clémence Boutière ◽  
Caroline Rey ◽  
Wafaa Zaaraoui ◽  
Arnaud Le Troter ◽  
Audrey Rico ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Motor Cortex ◽  
Resting State ◽  
Primary Motor Cortex ◽  
Rehabilitation Programme ◽  
Lower Limbs ◽  
Theta Burst Stimulation ◽  
Burst Stimulation ◽  
Functional Reorganization ◽  
Theta Burst

Background: Intermittent theta burst stimulation (iTBS) of the primary motor cortex improves transiently lower limbs spasticity in multiple sclerosis (MS). However, the cerebral mechanisms underlying this effect have never been investigated. Objective: To assess whether modulation of spasticity induced by iTBS is underlined by functional reorganization of the primary motor cortices. Methods: A total of 17 patients with MS suffering from lower limbs spasticity were randomized to receive real iTBS or sham iTBS during the first half of a 5-week indoor rehabilitation programme. Spasticity was assessed using the Modified Ashworth Scale and the Visual Analogue Scale at baseline, after the stimulation session and at the end of the rehabilitation programme. Resting-state functional magnetic resonance imaging (fMRI) was performed at the three time points, and brain functional networks topology was analysed using graph-theoretical approach. Results: At the end of stimulation, improvement of spasticity was greater in real iTBS group than in sham iTBS group ( p = 0.026). iTBS had a significant effect on the balance of the connectivity degree between the stimulated and the homologous primary motor cortex ( p = 0.005). Changes in inter-hemispheric balance were correlated with improvement of spasticity (rho = 0.56, p = 0.015). Conclusion: This longitudinal resting-state fMRI study evidences that functional reorganization of the primary motor cortices may underlie the effect of iTBS on spasticity in MS.

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