Posture-dependent modulation of marmoset cortical motor maps detected via rapid multichannel epidural stimulation

In this study, rapid topographical changes were detected in the forelimb motor maps in the primary motor cortex (M1) of awake marmoset monkeys using our previously developed accurate short-time stimulation mapping procedure ([Takemi et al. 2017][1]; [Kosugi et al. 2018][2]). The results revealed that although the hotspot (the location in M1 that elicited a forelimb muscle twitch with the lowest stimulus intensity) remained constant across postures, the stimulus intensity required to elicit the forelimb muscle twitch in the perihotspot region and the size of motor representations were posture-dependent. Hindlimb posture was particularly effective in inducing these modulations. The angle of the body axis relative to the gravitational vertical line did not alter the motor maps. These results provide a proof of concept that a rapid stimulation mapping system with chronically implanted cortical electrodes can capture the dynamic regulation of forelimb motor maps in natural conditions. The flexible nature of the motor maps necessitates the reconsideration of the results of motor control and neuroplasticity studies. Neural mechanisms regulating forelimb muscle representations in M1 by the hindlimb sensorimotor state warrant further exploration. ### Competing Interest Statement JU is a founder and CEO of the University Startup Company, LIFESCAPES Inc. for the research, development, and sales of rehabilitation devices including brain-computer interface. He receives a salary from LIFESCAPES Inc., and holds shares in LIFESCAPES Inc. This company does not have any relationship with the device or setup used in the present study. Other authors declare that the research was conducted in the absence of any commercial or financial relationship that could be construed as a potential conflict of interest. [1]: #ref-50 [2]: #ref-29