Visual context affects the perceived timing of tactile sensations elicited through intracortical microstimulation: a case study of two participants

Intracortical microstimulation (ICMS) is a technique to provide tactile sensations for a somatosensory brain-machine interface (BMI). A viable BMI must function within the rich, multisensory environment of the real world, but how ICMS is integrated with other sensory modalities is poorly understood. To investigate how ICMS percepts are integrated with visual information, ICMS and visual stimuli were delivered at varying times relative to one another. Both visual context and ICMS current amplitude were found to bias the qualitative experience of ICMS. In two tetraplegic participants, ICMS and visual stimuli were more likely to be experienced as occurring simultaneously in a realistic visual condition compared with an abstract one, demonstrating an effect of visual context on the temporal binding window. The peak of the temporal binding window varied but was consistently offset from zero, suggesting that multisensory integration with ICMS can suffer from temporal misalignment. Recordings from primary somatosensory cortex (S1) during catch trials where visual stimuli were delivered without ICMS demonstrated that S1 represents visual information related to ICMS across visual contexts. This study was a part of a clinical trial (NCT01964261).<b>NEW & NOTEWORTHY</b> Little is known about how the brain integrates tactile sensations elicited through intracortical microstimulation (ICMS) with visual information. This work investigates how visual cues affect the perception of tactile sensations from ICMS in two human participants. The results suggest that visual context can influence the perceived timing and the qualitative nature of artificial sensations, which is directly relevant to the implementation of a viable brain-machine interface (BMI) for individuals with tactile impairments.