Figure 4.

Simulink model of the VOR and anticipatory eye movement circuit. The black triangles represent synaptic weights used to optimize the simulated response. In the guinea pig simulations, K1=0.73, K2=K3=0.25; K5=0.5 and K4=0.75. The green boxes to the left represent inputs to the model. Head speed in space is an actual data segment of recorded head velocity. In the model, this input is low pass filtered to simulate a single pole semicircular canal transfer function (time constant = 4 seconds). The active head command is assumed to be a data segment of active head velocity. This signal is also low pass filtered to simulate an internal model of the semicircular canal (4 second time constant). The active head command is also used as an efference copy of the gaze command when the model simulates an anticipatory response. The blue summing junctions represent VO or ES vestibular neurons; the red summing junction represents a flocculus Purkinje cell and the gray box represents a “gaze” cell that could be located in cerebral cortex or in the cerebellum. The simulated output of the model is eye velocity. Note that eye velocity is also fed back via K5 to the P-cell.