Figure 4.

Summary of different types of nigral neurons. A, r values for the four types of neurons identified, showing high correlation between firing rate and either x- or y-coordinate. B, r values for the four types of neurons identified, showing much reduced correlation between firing rate and the alternative coordinate. For example, activity of X⁺ neurons is poorly correlated with the y-coordinate. C, Baseline firing rate during a 2 s period before trial onset. D, Timing of the neural activity (all four classes of neurons) in relation to movement. Cumulative probability distribution of the time it takes from reward delivery and the maximum or minimum value of the firing rates or position coordinates. For the position data, this is approximately the time it takes for the mouse to reach the farthest point from its resting position in either the x- or y-axis.