Analysis of the frequency response of the saccadic circuit: numerical simulations.

Fundamental mechanisms of a brain circuit's operation can be revealed by quantitative analysis of the system's dynamic behavior. This approach is particularly useful for investigation of motor circuits, which generate machine-like outputs and where systems control techniques can be applied to reveal the circuit behavior outside the dynamic range of volitional activation. As an extension of our previous study of the step response of the saccadic motor system, this paper presents analytical and numerical considerations for the frequency response of the saccadic circuit-the system response to a steady-state sinusoidal input. Consideration of these responses provides mechanistic explanation for several aspects of the biological circuit and formalizes constraints for viable models of the saccadic circuit. Most importantly, these studies provide quantitative predictions for comparison with experimental data in vivo and make explicit hypotheses about biological mechanisms for experimental verification.