Figure 1. The conceptual model used in this paper.

On the left are the biological mechanisms that support the model: (1) SMA is illustrated by the muscle contraction (large arrows), (2) the spinal reflex circuits, which mediate afferent (green) and efferent (red) connections, and (3) the descending signals from supraspinal circuits (blue), which modulate the activity of reflex circuits. Unfilled and filled circles illustrate the presence of excitatory and inhibitory reflex circuits, respectively. On the right, is the general model with the abstracted biological mechanisms as well as the processes that link them together, i.e. self-organization and modulation.