Macroscopic Neural Oscillation during Skilled Reaching Movements in Humans

The neural mechanism of skilled movements, such as reaching, has been considered to differ from that of rhythmic movement such as locomotion. It is generally thought that skilled movements are consciously controlled by the brain, while rhythmic movements are usually controlled autonomously by the spinal cord and brain stem. However, several studies in recent decades have suggested that neural networks in the spinal cord may also be involved in the generation of skilled movements. Moreover, a recent study revealed that neural activities in the motor cortex exhibit rhythmic oscillations corresponding to movement frequency during reaching movements as rhythmic movements. However, whether the oscillations are generated in the spinal cord or the cortical circuit in the motor cortex causes the oscillations is unclear. If the spinal cord is involved in the skilled movements, then similar rhythmic oscillations with time delays should be found in macroscopic neural activity. We measured whole-brain MEG signals during reaching. The MEG signals were analyzed using a dynamical analysis method. We found that rhythmic oscillations with time delays occur in all subjects during reaching movements. The results suggest that the corticospinal system is involved in the generation and control of the skilled movements as rhythmic movements.

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SPIKE-TRIGGERED INTRASPINAL MICROSTIMULATION IMPROVES MOTOR PERFORANCE IN AN AMBULATORY RAT MODEL OF SPINAL CORD INJURY

10.1101/2021.06.21.449323 ◽

2021 ◽

Author(s):

Jordan A Borrell ◽

Domenico Gattozzi ◽

Dora Krizsan-Agbas ◽

Randolph J. Nudo ◽

SHAWN B FROST

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Motor Cortex ◽

Rat Model ◽

Kinematic Analysis ◽

Intraspinal Microstimulation ◽

Custom Made ◽

Cord Injury ◽

And Control ◽

Activity Dependent

The purpose of this study was to determine if spike-triggered intraspinal microstimulation (ISMS) results in improved motor performance in an ambulatory rat model of spinal cord injury (SCI). Experiments were carried out in adult male Sprague Dawley rats with 175 kdyn moderate T8 contusion injury. Rats were randomly assigned to one of two groups: Control or Activity Dependent Stimulation (ADS) therapy. Four weeks post-SCI, all rats were implanted with a recording electrode in the left hindlimb motor cortex and a fine-wire, custom-made stimulating electrode in the contralateral lumbar spinal cord. Intracortical and intraspinal microstimulation were used to find sites of similar hip representation areas, which were paired together for ADS therapy. In the ADS therapy group, spike-stimulus conditioning was administered for 4 hours/day, 4 days/week, for 4 weeks via a tethered cable in a testing chamber. During therapy sessions, single-unit spikes were discriminated in real time in the hindlimb motor cortex and used to trigger stimulation in the spinal cord ventral horn. The optimal stimulus intensity (50% ISMS movement threshold) and spike-stimulus delay (10ms) determined in preliminary anesthetized preparations were used during ADS. Control rats were similarly implanted with electrodes but did not receive stimulation therapy. Motor performances of each rat were evaluated before SCI contusion, once a week post-SCI for four weeks (prior to electrode implantation), and once a week post-conditioning for four weeks. Behavioral testing included BBB scoring, Ledged Beam walking, Horizontal Ladder walking, treadmill kinematics via the DigiGait and TreadScan system, and open field walking using OptiTrack kinematic analysis. BBB scores were significantly improved in ADS rats compared to Control rats after 1 week of therapy. In the ADS therapy rats, BBB scores were significantly improved after two weeks of ADS therapy when compared to pre-therapy. Foot fault scores on the Horizontal Ladder were significantly lower in ADS rats compared to pre-therapy ADS and Control rats after 1 week of therapy and returned to pre-injury measures after three weeks of ADS therapy. The Ledged Beam test and kinematic analysis using the DigiGait and TreadScan system showed deficits after SCI in both ADS and Control rats but there were no significant differences between groups after 4 weeks of ADS therapy. These results show that activity dependent stimulation after spinal cord injury using spike-triggered ISMS enhances behavioral recovery of locomotor function as measured by the BBB score and the Horizontal Ladder task.

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Intestinal pattern and control measures adopted by patients with spinal cord trauma

Revista Estima ◽

10.30886/estima.v16.468 ◽

2018 ◽

Cited By ~ 2

Author(s):

Daniela Machado ◽

Gisela Assis

Keyword(s):

Spinal Cord ◽

Control Measures ◽

Spinal Cord Trauma ◽

And Control

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Effect of Transcranial Magnetic Stimulation on Bimanual Movements

Journal of Neurophysiology ◽

10.1152/jn.01063.2003 ◽

2005 ◽

Vol 93 (1) ◽

pp. 53-63 ◽

Cited By ~ 19

Author(s):

Jen-Tse Chen ◽

Yung-Yang Lin ◽

Din-E Shan ◽

Zin-An Wu ◽

Mark Hallett ◽

...

Keyword(s):

Transcranial Magnetic Stimulation ◽

Motor Cortex ◽

Left Hemisphere ◽

Magnetic Stimulation ◽

Normal Subjects ◽

Left Index Finger ◽

Rhythmic Movements ◽

Bimanual Movements ◽

Ipsilateral Stimulation ◽

The Right

Transcranial magnetic stimulation (TMS) of the motor cortex can interrupt voluntary contralateral rhythmic limb movements. Using the method of “resetting index” (RI), our study investigated the TMS effect on different types of bimanual movements. Six normal subjects participated. For unimanual movement, each subject tapped either the right or left index finger at a comfortable rate. For bimanual movement, index fingers of both hands tapped in the same (in-phase) direction or in the opposite (antiphase) direction. TMS was applied to each hemisphere separately at various intensities from 0.5 to 1.5 times motor threshold (MT). TMS interruption of rhythm was quantified by RI. For the unimanual movements, TMS disrupted both contralateral and ipsilateral rhythmic hand movements, although the effect was much less in the ipsilateral hand. For the bimanual in-phase task, TMS could simultaneously reset the rhythmic movements of both hands, but the effect on the contralateral hand was less and the effect on the ipsilateral hand was more compared with the unimanual tasks. Similar effects were seen from right and left hemisphere stimulation. TMS had little effect on the bimanual antiphase task. The equal effect of right and left hemisphere stimulation indicates that neither motor cortex is dominant for simple bimanual in-phase movement. The smaller influence of contralateral stimulation and the greater effect of ipsilateral stimulation during bimanual in-phase movement compared with unimanual movement suggest hemispheric coupling. The antiphase movements were resistant to TMS disruption, and this suggests that control of rhythm differs in the 2 tasks. TMS produced a transient asynchrony of movements on the 2 sides, indicating that both motor cortices might be downstream of the clocking command or that the clocking is a consequence of the 2 hemispheres communicating equally with each other.

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Exercise Ameliorates Spinal Cord Injury by Changing DNA Methylation

Cells ◽

10.3390/cells10010143 ◽

2021 ◽

Vol 10 (1) ◽

pp. 143

Author(s):

Ganchimeg Davaa ◽

Jin Young Hong ◽

Tae Uk Kim ◽

Seong Jae Lee ◽

Seo Young Kim ◽

...

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Motor Cortex ◽

Functional Recovery ◽

Treadmill Exercise ◽

Exercise Group ◽

Control Group ◽

Epigenetic Changes ◽

Cord Injury ◽

The Brain

Exercise training is a traditional method to maximize remaining function in patients with spinal cord injury (SCI), but the exact mechanism by which exercise promotes recovery after SCI has not been identified; whether exercise truly has a beneficial effect on SCI also remains unclear. Previously, we showed that epigenetic changes in the brain motor cortex occur after SCI and that a treatment leading to epigenetic modulation effectively promotes functional recovery after SCI. We aimed to determine how exercise induces functional improvement in rats subjected to SCI and whether epigenetic changes are engaged in the effects of exercise. A spinal cord contusion model was established in rats, which were then subjected to treadmill exercise for 12 weeks. We found that the size of the lesion cavity and the number of macrophages were decreased more in the exercise group than in the control group after 12 weeks of injury. Immunofluorescence and DNA dot blot analysis revealed that levels of 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) in the brain motor cortex were increased after exercise. Accordingly, the expression of ten-eleven translocation (Tet) family members (Tet1, Tet2, and Tet3) in the brain motor cortex also elevated. However, no macrophage polarization was induced by exercise. Locomotor function, including Basso, Beattie, and Bresnahan (BBB) and ladder scores, also improved in the exercise group compared to the control group. We concluded that treadmill exercise facilitates functional recovery in rats with SCI, and mechanistically epigenetic changes in the brain motor cortex may contribute to exercise-induced improvements.

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Transcranial Magnetic Stimulation as a Tool to Investigate Motor Cortex Excitability in Sport

Brain Sciences ◽

10.3390/brainsci11040432 ◽

2021 ◽

Vol 11 (4) ◽

pp. 432

Author(s):

Fiorenzo Moscatelli ◽

Antonietta Messina ◽

Anna Valenzano ◽

Vincenzo Monda ◽

Monica Salerno ◽

...

Keyword(s):

Transcranial Magnetic Stimulation ◽

Motor Cortex ◽

Magnetic Stimulation ◽

Motor Coordination ◽

Cortical Excitability ◽

Non Invasive ◽

Motor Cortex Excitability ◽

Invasive Method ◽

And Control ◽

The Impact

Transcranial magnetic stimulation, since its introduction in 1985, has brought important innovations to the study of cortical excitability as it is a non-invasive method and, therefore, can be used both in healthy and sick subjects. Since the introduction of this cortical stimulation technique, it has been possible to deepen the neurophysiological aspects of motor activation and control. In this narrative review, we want to provide a brief overview regarding TMS as a tool to investigate changes in cortex excitability in athletes and highlight how this tool can be used to investigate the acute and chronic responses of the motor cortex in sport science. The parameters that could be used for the evaluation of cortical excitability and the relative relationship with motor coordination and muscle fatigue, will be also analyzed. Repetitive physical training is generally considered as a principal strategy for acquiring a motor skill, and this process can elicit cortical motor representational changes referred to as use-dependent plasticity. In training settings, physical practice combined with the observation of target movements can enhance cortical excitability and facilitate the process of learning. The data to date suggest that TMS is a valid technique to investigate the changes in motor cortex excitability in trained and untrained subjects. Recently, interest in the possible ergogenic effect of non-invasive brain stimulation in sport is growing and therefore in the future it could be useful to conduct new experiments to evaluate the impact on learning and motor performance of these techniques.

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