Figure 11.

Right⁺ (X⁻) neuron increases firing during rightward movement and decreases firing during leftward movement. A, Detailed illustration of the correlation between firing rate and x-coordinates on a trial-by-trial basis. Neural activity and x-coordinates from 10 consecutive trials are shown. Each row represents a single trial. B, Neural and position data from a single trial are selected and compared. x-axis position changes during each movement are reflected in the firing rate of this neuron. C, Average firing rate changes and changes in different movement parameters. The plots on the right show velocity and acceleration data for the same movements. D, Using an egocentric reference frame, the direction of firing rate changes corresponds to the direction of movement. There was therefore a negative correlation between firing rate and raw x-coordinate value but a positive correlation between firing rate and distance in the rightward direction (p < 0.001). The correlation with the nonpreferred Cartesian axis is also shown. The diagram on the right shows the gradient of firing rate in relation to position coordinates.