Pattern Reorganization of Corticomuscular Connection with the Tactile Stimulation

Sensitivity to tactile stimuli is an indispensable feedback in human motion control. However, previous studies on tactile stimulation mainly focused on the effects of superficial tactile stimulation on the motor cortex, but the role of deep tactile feedback stimulation in motor tasks is not clear. Corticomuscular coherence (CMC) is an effective method for studying dynamic motion tasks. Recent evidence suggests that CMC is enhanced by tactile stimulation in the beta-band. But, the mechanism of tactile stimulation in dynamic motor tasks is still undetermined. In order to explore the role of tactile stimulation in dynamic motion tasks, we examined the correlation between EEG/EMG in a motor task with tactile stimulus input, including the corticomuscular coherence and the causal connections (convergent cross mapping, CCM). In this study, seventeen subjects were recruited to complete stimuli and non-stimuli motor tasks. After the experiment, the time–frequency analysis of CMC showed that the somatosensory association cortex was clearly involved in the dynamic motor tasks. During the contraction of hand muscles, the activity of CMC was concentrated in gamma band, while in the maintenance process, it was concentrated in beta-band. After eliminating the distractors of attention, we did not find a similar result as previous studies had found—tactile stimuli lead to increased CMC activity in gamma band. On the contrary, CCM causality analysis showed that tactile stimulation could significantly enhance the connection between the cerebral cortex and a muscle. We speculate that tactile stimulation can enhance the corticomuscular causal relationship, and that the effect of tactile stimulation on corticomuscular coherence may have more complex mechanisms. This study provides new insights into neural mechanism of tactile feedback and provides more information about the causality of brain networks in tactile feedback task.