Fig. 8.
Individual VO neurons display velocity detection thresholds that are greater than or equal to those of afferents. A: table velocity (upper) and time-dependent firing rate (lower) during sinusoidal stimulation. A comparison was made between the distribution of the instantaneous firing rate when the table velocity is equal to a given value (Vi) and that obtained when the table velocity is equal to 0. B: plot of the instantaneous firing rate as a function of table velocity for an example VO neuron. Also shown are schematic representations of the instantaneous firing rate distributions for Vi = 20 and 40°/s. C: neurometric function obtained using receiver operating characteristic (ROC) analysis of the firing-rate distributions for different values of Vi. The detection threshold corresponds to 76% probability of correct detection (dashed lines). D: population-averaged detection threshold values for VO neurons and afferents as a function of the sinusoidal stimulus frequency. Error bars indicate 1 SE. E: velocity thresholds of VO neurons and afferents for discriminating between 8- and 16-Hz sinusoidal head rotations.