Single and Multi-Site Cortical Stimulation Related to Human Sensorimotor Function

Somatosensory feedback is crucial for precise control of our body and thereby affects various sensorimotor-related brain areas for movement control. Electrical stimulation on the primary somatosensory cortex (S1) elicits various artificial somatosensations. However, replicating the spatiotemporal dynamics of somatosensory feedback and fine control of elicited somatosensation are still challenging. Furthermore, how and where the somatosensory feedback interacts with neural activity for sensorimotor processing is unclear. Here, we replicate the spatiotemporal dynamics of somatosensory feedback and control the quality of elicited somatosensation using multi-site direct cortical stimulation (DCS). We also investigate how and where the neural feedback activity interacts with neural activity for motor processing by stimulating the downstream areas of the S1. We found that multi-site DCS on the S1 elicits different sensations simultaneously. Using the artificial feedback, blindfolded patients could efficiently perform a DCS-guided reach-and-grasp task successfully. Interestingly, we also found that multi-site DCS close to each other elicits different qualities of somatosensation in the same body part. Additionally, we found that DCS on the ventral premotor area (vPM) can affect hand grasping with eliciting artificial sensation of the hand. Throughout this study, we showed that semi-invasive, macro-level, and multi-site DCS can precisely elicit/modulate somatosensations in human. We suggest that activation of multiple cortical areas elicits simultaneous and independent somatosensations and that interplay among the stimulated sites can change the somatosensation quality. Finally, the results of vPM stimulation indicate that vPM has a critical role in function-specific sensorimotor interactions, such as hand grasping.