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Abstract

The importance of sensation in motor control is often under-appreciated despite the severe deficits that occur when that signal is lost. Thus, restoring sensation in bionic limbs is a crucial step in the advancement of prosthetic design. In patients with spinal cord injuries, this is accomplished by implanting arrays into primary somatosensory cortex (S1) through which the sense of touch can be restored with the use of intracortical microstimulation (ICMS). When evoking artificial sensations, the location of contact with an object is one crucial piece of information that is necessary for proper object manipulation. First, I demonstrate that the use of ICMS in Brodmann’s Area 1 of S1 is a viable way of communicating contact location in a bionic limb as the sensations evoked through ICMS are stable over time and demonstrate the feasibility of this in a digit discrimination task. Second, I investigate the connectivity between S1 and primary motor cortex (M1) using ICMS and establish that there are connections between these regions through causal activation of M1 via ICMS of S1. Furthermore, I demonstrate that this connectivity is somatotopic with single digit resolution. I then considered the functional consequences of these connections on the performance of bionic hands in motor tasks and found that the use of linear stimulation impaired the decoding of motor intent and disrupted performance while biomimetic stimulation allowed us to provide sensory feedback without disrupting performance. Finally, I discuss the importance of these findings for the design of better prosthetics and our understanding of sensorimotor interactions.

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