Gregory Shakhnarovich, Sung-phil Kim, Michael Black
Neural motor prostheses (NMPs) require the accurate decoding of motor cortical population activity for the control of an artiﬁcial motor system. Previous work on cortical decoding for NMPs has focused on the recovery of hand kinematics. Human NMPs however may require the control of computer cursors or robotic devices with very different physical and dynamical properties. Here we show that the ﬁring rates of cells in the primary motor cortex of non-human primates can be used to control the parameters of an artiﬁcial physical system exhibiting realistic dynamics. The model represents 2D hand motion in terms of a point mass connected to a system of idealized springs. The nonlinear spring coefﬁcients are estimated from the ﬁring rates of neurons in the motor cortex. We evaluate linear and a nonlinear decoding algorithms using neural recordings from two monkeys performing two different tasks. We found that the decoded spring coefﬁcients produced accurate hand trajectories compared with state-of-the-art methods for direct decoding of hand kinematics. Furthermore, using a physically-based system produced decoded movements that were more “natural” in that their frequency spectrum more closely matched that of natural hand movements.