Loss of proprioception is known to severely impair motor control, but the neural mechanisms by which proprioception aids in the planning and execution of visually guided movements are not well understood. We investigated the impact of providing proprioceptive feedback to a human subject with tetraplegia and intact sensation who was implanted with two 100-channel micro- electrode arrays in primary motor cortex (M1).

Proprioceptive feedback induced low-rank fluctuations in M1 neural activity that masked the tuning of motor neurons. In other words, when unaccounted for, sensory feedback actually disrupted the decoding performance of the subject's brain-machine interface. I developed an improved statistical model of M1 encoding that accounts for the latent shared fluctuations induced by proprioceptive signals.