Figure 3.

(a) Exogenous BMIs: Decoding motor intent signals involves reducing the dimensionality of the sampled neural state space to a small number of control variables (Degrees of Freedom) in the task space. The converse is true in the encoding of sensory feedback where stimulation through a small number of channels likely activates a larger number of functionally heterogeneous cells. Stimulation is triggered based on the dynamics of the end effector state. The congruence between the artificial somatosensory feedback and other forms of feedback (e.g. visual) could facilitate BMI sensorimotor learning.

(b) Endogenous BMIs: Stimulation is triggered based on events in the neural state space independent of those in the task space. Neurons in the recording and stimulation sites are functionally distinct before conditioning, but become functionally similar after conditioning, as demonstrated in the behavioral task space. The time scale of the closed loop operation is critical to induce Hebbian-like plasticity that is consistent with strengthening synapses between the recording and stimulation sites.