Fig. 3.

Angular velocity effect on HD cells depends on the separation angle. A: color-coded scatterplot of spiking frequency plotted against head direction (x-axis) and angular velocity (y-axis) from a sample unit with a separation angle (SA) < 8°. Scatterplot on right represents the correlation between the angular velocity and the aligned head direction (centered to 180°) for the recorded spikes (red symbols). B: color-coded scatterplot of spiking frequency (left) and for aligned head direction (right) from a sample unit with a separation angle > 8°. The Pearson's correlation between angular velocity and head direction is shown. C: average firing frequency vs. angular velocity plot of all units with a separation angle < 8° (n = 56) against all units with a separation angle > 8° (n = 34) (means ± SE).