Figure 1. Illustration of the behavioral task and context changes.

(A) Experimental setup during manipulandum control and brain-machine interface (BMI) control experiments. The monkey individuates their index and middle-ring-small finger group, moving each in the manipulandum in order to acquire targets on the screen in front of them. During this task, neural activity and finger positions are both recorded. A model relating neural activity to intended finger movements can be trained and then used in real time to control the virtual hand in front of them. (B) Illustration of the possible finger movements. For 2-degree-of-freedom (2-DOF) movements, the index flexion is represented on the x-axis and MRS flexion is represented on the y-axis. In some tasks the monkeys also did a 1-DOF movement, which required flexing or extending all fingers together. (C) To alter the context of the task, the manipulandum could be rotated so that the wrist was flexed and torsion springs could be added to the underside of the finger doors. The torsion springs were at rest when the finger doors were at full extension and thus resisted flexion and assisted with extension.