A simple model of the eye muscles

Motorneuron firing rate is proportional to two factors:

• the eye's position (e) from center because the muscle must act against the spring like elasticity (k) of the muscles and globe's attachments and
• the eye's velocity (é) because the muscle must act against the viscosity (r) of the muscle and globe's attachments.

Thus in this circuit mn = ré + ke.

A step increase in motorneuron firing rate will produce an exponential change in eye position (e).