New paper accepted at Nature Neuroscience, with Jake Stroud, Mason Porter and Tim P. Vogels
Motor primitives in space and time via targeted gain modulation in cortical networks
Congratulations Jake on a great PhD thesis, and a cool paper now in press at Nature Neuroscience!
Motor cortex (M1) exhibits a rich repertoire of activities to support the generation of complex movements. Although recent neuronal network models capture many qualitative aspects of M1 dynamics, they can generate only a few distinct movements. Additionally, it is unclear how M1 efficiently controls movements over a wide range of shapes and speeds. We demonstrate that simple modulation of neuronal input — output gains in recurrent neuronal network models with fixed connectivity can dramatically reorganize neuronal activity and consequently downstream muscle outputs. Consistent with the observation of diffuse neuromodulatory projections to M1, we show that a relatively small number of modulatory control units provide sufficient flexibility to adjust high-dimensional network activity using a simple reward-based learning rule. Furthermore, novel movements can be assembled from previously-learned primitives and we can separately change movement speed while preserving movement shape. Our results provide a new perspective on the role of modulatory systems in controlling recurrent cortical activity.