"Consolidation of Prosthetic Motor Skill in Primates."

Research in Brain-Machine Interfaces (BMIs) has led to demonstrations of rodents, non-human primates and humans controlling prosthetic devices in real-time through modulation of neural signals. In particular, cortical BMI studies have shown that improvements in performance require learning and are associated with changes in neuronal tuning properties. As these studies incorporated variable ensembles of neurons from day to day, and required daily modifications to the transform of cortical activity into motor output, little is known about long-term consolidation of prosthetic motor skill. Here we demonstrate consolidation, defined as motor skill that is retained, readily recalled and resistant to interference, in two macaque monkeys performing a center-out reaching task using a brain-controlled computer cursor under visual feedback. When a fixed transform was applied to stable recordings from an ensemble of primary motor cortex (M1) neurons across days, there was dramatic long-term consolidation of prosthetic motor skill. This process created a directional tuning map for prosthetic function that was stable across days. Surprisingly the same set of neurons could encode a second motor map without interference with the first map. In contrast, daily modification of the transform, in a manner similar to past studies, resulted in variable performance and an unstable motor map. Taken together, our results demonstrate that the primate brain can achieve skilled control of a neuroprosthetic device through consolidation of a motor memory.