Figure 5.

Changes in the firing rate of a typical vestibular-only (VO) neuron that codes the yaw component of velocity storage during head rotation at 60°/s (A), 90°/s (B), and 120°/s (C). (A–C) In each section, after being in darkness for 5 s, the animal was rotated to the left (counterclockwise) and then stopped while in darkness (primate position, tooth-like, and constant levels, respectively). Then rotation was repeated in the opposite (clockwise) direction. This sequence induces per-rotatory nystagmus to the right (Negative Eye Velocity) which gradually declined to 0. When rotation was stopped, it induces post-rotatory nystagmus in the opposite direction (positive eye velocity). This sequence of per- and post-rotatory nystagmus was repeated in the opposite directions. The experiment animal was extremely drowsy, and there was a sudden decline of slow phase eye velocities to 0. Drowsiness, however, did not the affect firing rate of this VO neuron. (D) Relationship between the time constants of velocity storage determined from slow the phase eye velocity (ordinate) and from the neuronal firing rate (abscissa). Each data point on this graph represents a time constant measured for the oculomotor response and corresponding neuronal response. This is shown in the two responses in graphs (A–C). The black line is the linear regression of the data.