Designing stimulation patterns for an afferent BMI: Representation of kinetics in somatosensory cortex

In recent years, much attention has been focused on developing stimulating strategies for somatosensory prostheses. One application of such a somatosensory prosthesis is to supply proprioceptive feedback in a brain machine interface application. One strategy for the development of such a stimulation regime is to mimic the natural representation of limb state variables. In this paper, we demonstrate that end point force is represented in primary somatosensory cortex of the macaque and force, in addition to velocity, can be decoded from S1 neural recordings. Force is represented in S1 in both a movement and isometric tasks; however, models that predict force in one condition do not generalize to the other. Possible interpretations of these apparently contradictory results are discussed.