Distinct population code for movement kinematics and changes of ongoing movements in human subthalamic nucleus
The subthalamic nucleus (STN) is theorized to globally suppress movement through connections with downstream basal ganglia structures. Current theories are supported by increased STN activity when subjects withhold an uninitiated action plan, but a critical test of these theories requires studying STN responses when an ongoing action is replaced with an alternative. Here, we perform this test using an extended reaching task with instructions to switch movement trajectory mid-action. We show that STN activity decreases during action switches, contrary to prevalent theories. Further, beta oscillations in the local field potential in STN, which are associated with movement inhibition do not show increased power or entraining of neuronal firing during switches. We report an inhomogeneous population neural code in STN, with one sub-population encoding movement kinematics and direction and another encoding unexpected action switches. We suggest an elaborate neural code in STN that contributes to planning actions and changing the plans.