The motor nervous system transmits motion control information through nervous oscillations, which causes the synchronous oscillatory activity of the corresponding muscle to reflect the motion response information and give the cerebral cortex feedback, so that it can sense the state of the limbs. This synchronous oscillatory activity can reflect connectivity information of electroencephalography-electromyography (EEG-EMG) functional coupling. The strength of the coupling is determined by various factors including the strength of muscle contraction, attention, motion intention etc. It is very significant to study motor functional evaluation and control methods to analyze the changes of EEG-EMG synchronous coupling caused by different factors. This article mainly introduces and compares coherence and Granger causality of linear methods, the mutual information and transfer entropy of nonlinear methods in EEG-EMG synchronous coupling, and summarizes the application of each method, so that researchers in related fields can understand the current research progress on analysis methods of EEG-EMG synchronous systematically.
Electroencephalography ; Electromyography ; Humans ; Motor Cortex ; physiology ; Muscle, Skeletal ; physiology ; Research

In contrast to traditional representational perspectives in which the motor cortex is involved in motor control via neuronal preference for kinetics and kinematics, a dynamical system perspective emerging in the last decade views the motor cortex as a dynamical machine that generates motor commands by autonomous temporal evolution. In this review, we first look back at the history of the representational and dynamical perspectives and discuss their explanatory power and controversy from both empirical and computational points of view. Here, we aim to reconcile the above perspectives, and evaluate their theoretical impact, future direction, and potential applications in brain-machine interfaces.
Biomechanical Phenomena ; Brain-Computer Interfaces ; Motor Cortex/physiology* ; Neurons/physiology*

PURPOSE: To investigate the influence of 2 phases of short interval intracortical inhibition (SICI) on the cortical silent period (SP). MATERIALS AND METHODS: Single- and paired-pulse transcranial magnetic stimulations (TMSs) at 1 and 2.5ms interstimulus intervals (ISIs) were applied to the left motor cortex in 12 healthy subjects while their right hand muscles were moderately activated. Conditioning stimulation intensity was 90% of the active motor threshold (AMT). Test stimulation intensities were 120, 140, 160, 180, 200, 220, 240, 260% of the AMT and at 100% of the maximal stimulator output, the order of which was arranged randomly. The rectified electromyography area of motor evoked potential (MEP) and duration of the SP were measured off-line using a computerized program. RESULTS: At high-test stimulation intensities, MEP areas were saturated in both single- and paired-pulse stimulations, except that saturated MEPs were smaller for the paired-pulse TMS at 1ms ISI than for the other conditions. As the test stimulation intensity increased, SP was progressively prolonged in both single- and paired-pulse stimulations but was shorter in paired-pulse than single-pulse TMS. Overall, the ratio of SP duration/MEP area was comparable between single- and paired-pulse TMS except for the paired-pulse TMS at 1 ms ISI with a test stimulation intensity at 140-180% of the AMT, in which the ratio was significantly higher than in the single pulse TMS. CONCLUSION: These results suggest that 2 phases of SICI modulate MEP saturation and SP duration differently and provide additional evidence supporting the view that 2 phases of SICI are mediated by different inhibitory mechanisms.
Adult ; Evoked Potentials, Motor/*physiology ; Female ; Humans ; Male ; Motor Cortex/*physiology ; Transcranial Magnetic Stimulation

OBJECTIVEThe local field potential (LFP) is a summation of dendritic potentials. The main objective of the present work is to view the features of LFP in M1 during the experimental rat pushed a paddle with the right forelimb.

METHODSFour rats were trained to press a paddle with the right forelimb for water. Then Two bundle micro-electrode with four channels were implanted into the rat's left and right primary motor cortex (M1)(AP + 3.0 mm, ML +/- 1.6 mm, H-1.6 mm) with stereotaxic apparatus. After three days recovery, 8-channel Deep-EEG and the pulse signal of paddle pressed were recorded during the rats were in operant chamber, and at the same time, the behavior were also recorded with video recorder.

RESULTSThe LFP in left M1 were defined as the substance between two channel deep-EEG. It is found that low frequency, high amplitude signal appear aligned with the paddle pressed pulse signals. With threshold detect method, about 80% press-paddle behavior could be detected.

CONCLUSIONThe result indicates that LFPs in this position in M1 are relative to forelimb's movement, and a powerful brain-computer interface system maybe developed with the LFPs.

Animals ; Brain-Computer Interfaces ; Evoked Potentials, Motor ; physiology ; Male ; Microelectrodes ; Motor Cortex ; physiology ; Movement ; physiology ; Rats ; Rats, Sprague-Dawley

Full evidence and obvious reasons made it possible to arrive at the conclusion that the nature of transmission upon cerebrospinal neurons is overwhelmingly mechanical, not only in the periphery- between various receptors and afferent nerve terminals, and between surrounding tissues and free nerve endings- but also in the cerebral cortex. When viewed from the standpoint of the everchanging patterns of natural mechanical stimuli, the neurons in the conscious cerebral cortex and the pain endings in an acute inflammatory locus have the same situation very much in common. It is quite likely that natural mechanical stimuli dominate over cerebrospinal nervous phenomena and physiologists have been watching the missing mechanism at work in every experiment upon afferent nerve terminals and cerebral cortex that they have done. The terms "psychic tension" and "central excitatory state" comparable to muscular tonus are of interest because they involve the use of mathematical techniques in psychology and neurophysiology. They are capable of becoming weak or strong, and they serve as an inner stimulus to give impetus to behavior. Unfortunately, however, it is an elusive inner stimulus, and it defies a lucid definition. But natural mechanical stimuli embody the psychic tension and the central excitatory state ultimately. It seems now that we just found a place where constant complaints against neurophysiology and physiological psychology are ventilated. We may conclude that natural mechanical stimuli are the leading direct stimuli to cerebrospinal neurons in the human body, and the plastic and developmental nervous phenomena and mental phenomena can be explained objectively by a familliar datum of mechanical energy and that we can reasonably expect the day of regarding material world and spiritual world in the monistic conception of matter-energy system.
Animals ; Anura ; Cerebral Cortex/*physiology ; Human ; In Vitro ; Motor Neurons/physiology ; Nerve Endings/physiology ; Receptors, Sensory/*physiology ; Spinal Cord/*physiology

Intracortical microstimulation (ICMS) is a technique that was developed to derive movement representation of the motor cortex. Although rats are now commonly used in motor mapping studies, the precise characteristics of rat motor map, including symmetry and consistency across animals, and the possibility of repeated stimulation have not yet been established. We performed bilateral hindlimb mapping of motor cortex in six Sprague-Dawley rats using ICMS. ICMS was applied to the left and the right cerebral hemisphere at 0.3 mm intervals vertically and horizontally from the bregma, and any movement of the hindlimbs was noted. The majority (80%+/-11%) of responses were not restricted to a single joint, which occurred simultaneously at two or three hindlimb joints. The size and shape of hindlimb motor cortex was variable among rats, but existed on the convex side of the cerebral hemisphere in all rats. The results did not show symmetry according to specific joints in each rats. Conclusively, the hindlimb representation in the rat motor cortex was conveniently mapped using ICMS, but the characteristics and inter-individual variability suggest that precise individual mapping is needed to clarify motor distribution in rats.
Animals ; *Brain Mapping ; Electric Stimulation ; Electrodes ; Hindlimb/*physiology ; Male ; Motor Cortex/*physiology ; Rats ; Rats, Sprague-Dawley

The secondary motor cortex (M2) encodes choice-related information and plays an important role in cue-guided actions. M2 neurons innervate the dorsal striatum (DS), which also contributes to decision-making behavior, yet how M2 modulates signals in the DS to influence perceptual decision-making is unclear. Using mice performing a visual Go/No-Go task, we showed that inactivating M2 projections to the DS impaired performance by increasing the false alarm (FA) rate to the reward-irrelevant No-Go stimulus. The choice signal of M2 neurons correlated with behavioral performance, and the inactivation of M2 neurons projecting to the DS reduced the choice signal in the DS. By measuring and manipulating the responses of direct or indirect pathway striatal neurons defined by M2 inputs, we found that the indirect pathway neurons exhibited a shorter response latency to the No-Go stimulus, and inactivating their early responses increased the FA rate. These results demonstrate that the M2-to-DS pathway is crucial for suppressing inappropriate responses in perceptual decision behavior.
Mice ; Animals ; Motor Cortex ; Corpus Striatum/physiology* ; Neostriatum ; Neurons/physiology* ; Reaction Time

OBJECTIVES: To compare the effects of electroacupuncture (EA) with different time intervals on corticospinal excitability of the primary motor cortex (M1) and the upper limb motor function in healthy subjects and observe the after-effect rule of acupuncture. METHODS: Self-comparison before and after intervention design was adopted. Fifteen healthy subjects were included and all of them received three stages of trial observation, namely EA₀ group (received one session of EA), EA_6h group (received two sessions of EA within 1 day, with an interval of 6 h) and EA_48h group (received two sessions of EA within 3 days, with an interval of 48 h). The washout period among stages was 1 week. In each group, the needles were inserted perpendicularly at Hegu (LI 4) on the left side, 23 mm in depth and at a non-acupoint, 0.5 cm nearby to the left side of Hegu (LI 4), separately. Han's acupoint nerve stimulator (HANS-200A) was attached to these two needles, with continuous wave and the frequency of 2 Hz. The stimulation intensity was exerted higher than the exercise threshold (local muscle twitching was visible, and pain was tolerable by healthy subjects, 1-2 mA ). The needles were retained for 30 min. Using the single pulse mode of transcranial magnetic stimulation (TMS) technique, before the first session of EA (T0) and at the moment (T1), in 2 h (T2) and 24 h (T3) after the end of the last session of EA, on the left first dorsal interosseous muscle, the amplitude, latency (LAT), resting motor threshold (rMT) of motor evoked potentials (MEPs) and the completion time of grooved pegboard test (GPT) were detected. Besides, in the EA_6h group, TMS was adopted to detect the excitability of M1 (amplitude, LAT and rMT of MEPs) before the last session of EA (T0*). RESULTS: The amplitude of MEPs at T1 and T2 in the EA₀ group, at T0* in the EA_6h group and at T1, T2 and T3 in the EA_48h group was higher when compared with the value at T0 in each group separately (P<0.001). At T1, the amplitude of MEPs in the EA₀ group and the EA_48h group was higher than that in the EA_6h group (P<0.001, P<0.01); at T2, it was higher in the EA₀ group when compared with that in the EA_6h group (P<0.01); at T3, the amplitude in the EA₀ group and the EA_6h group was lower than that of the EA_48h group (P<0.001). The LAT at T1 was shorter than that at T0 in the three groups (P<0.05), and the changes were not obvious at the rest time points compared with that at T0 (P > 0.05). The GPT completion time of healthy subjects in the EA₀ group and the EA_48h group at T1, T2 and T3 was reduced in comparison with that at T0 (P<0.001). The completion time at T3 was shorter than that at T0 in the EA_6h group (P<0.05); at T2, it was reduced in the EA_48h group when compared with that of the EA_6h group (P<0.05). There were no significant differences in rMT among the three groups and within each group (P>0.05). CONCLUSIONS Under physiological conditions, EA has obvious after-effect on corticospinal excitability and upper limb motor function. The short-term interval protocol (6 h) blocks the after-effect of EA to a certain extent, while the long-term interval protocol (48 h) prolongs the after-effect of EA.
Humans ; Electroacupuncture ; Motor Cortex/physiology* ; Transcranial Magnetic Stimulation/methods* ; Upper Extremity ; Exercise ; Muscle, Skeletal/physiology*

It is the functional connectivity between motor cortex and muscle that directly relates to the rehabilitation of the dysfunction in upper limbs and neuromuscular activity status, which can be detected by electroencephalogram-electromyography (EEG-EMG) coherence analysis. In this study, based on coherence analysis method, we process the acquisition signals which consist of 9 channel EEG signal from motor cortex and 4 channel EMG signal from forearm, by using 4 groups of hand motions in the healthy subjects, including flexor digitorum, extensor digitorum, wrist flexion, and wrist extension. The results showed that in the β-band, the coherence coefficients between C3 and flexor digitorum (FD) was greater than extensor digitorum (ED) in the right hand flexor digitorum movement; the coherence coefficients between C3 and ED was greater than FD in the right hand extensor digitorum movement; the coherence coefficients between C3 and flexor carpi ulnaris (FCU) was greater than extensor carpi radialis (ECR) in the right hand wrist flexion movement; the coherence coefficients between C3 and ECR was greater than FCU in the right hand wrist extension movement. This analysis provides experimental basis to explore the information decoding of hand motion based on corticomuscular coherence (CMC).
Electroencephalography ; Electromyography ; Healthy Volunteers ; Humans ; Motor Cortex ; physiology ; Movement ; Muscle, Skeletal ; physiology ; Range of Motion, Articular ; Wrist ; physiology ; Wrist Joint ; physiology

OBJECTIVETo investigate the brain functional laterality in motor areas during motor execution systematically.

METHODSFunctional magnetic resonance imaging (fMRI) was employed combined with right hand sequential finger movement task to investigate brain activation pattern and laterality in 8 right-handed subjects. 3dDeconvolve program of AFNI was used to estimate the hemodynamic response function and to generate activation maps. Then the laterality index (LI) was calculated and tested statistically.

RESULTAll motor areas including the areas which were previously considered to be engage in movement preparation only were activated in movement execution. In the activation map, it appeared left lateralization in cerebra and right lateralization in cerebella. After further statistical test, it was found that in primary motor area (M1), supplementary motor area (SMA) and posterior parietal cortex (PPC), there were left lateralization. While in premotor cortex (PMC), cingulate gyrus and basal ganglia (BG), the lateralization tendency was not obvious. The activation in cerebella is characterized with right lateralization.

CONCLUSIONThough there are tiny differences among subjects, most of the motor areas appear lateralized activation. Past studies only observed laterality in several motor areas. It may be due to the difficulty of the task or the experimental design.

Adult ; Brain ; physiology ; Female ; Functional Laterality ; physiology ; Humans ; Image Processing, Computer-Assisted ; Magnetic Resonance Imaging ; Male ; Motor Cortex ; physiology