Figure 8.

Sensitivity of Type 2 neurons to reward variance. A, Experimental design. Four fractal CSs indicated four different levels of reward variance. Possible reward amounts are indicated with asterisks above each fractal. The large and small reward amounts occurred equally likely. The expected value was the same across the CSs. S.D, SD of reward amount. B, Average activity of 29 mBF Type 2 neurons (16 in Monkey H, 13 in Monkey P), shown separately for each of the four fractals. C, CS responses shown individually for the 29 neurons (normalized to the maximum CS response; from 0 to 1). D, Average CS responses of the same neurons. *p < 0.05 (paired sign-rank test). Error bars indicate SE.