Table 5.

Number of cells that showed significant dependence on presentation frequency of individual stimuli among those that showed significant reward dependence

	100–500 ms	500–900 ms	900–1300 ms	Total 1	Total 2
PRh	4/16	2/15	1/22	7/53	3/36
TE	0/8	0/8	0/11	0/27	0/23

The denominator indicates the number of cells that showed significant (p < 0.05/3) reward dependence in each pre-reward window. The numerator indicates the number of cells, among those that showed significant reward dependence, in which a significant (p < 0.05, one-tailed) correlation was found between the firing rate to each stimulus and the presentation frequency of the stimulus in the direction consistent with that of reward dependence of the cell (for cells that showed larger activities in rewarded trials, the tendency to show larger activities to stimuli presented less frequently was tested, and for cells that showed larger activities in unrewarded trials, the tendency to show larger activities to stimuli presented more frequently was tested). The mean responses and mean presentation frequency in each motor–reward condition were subtracted from individual responses and frequencies before the regression analysis. Total 1 provides simple sums of the numbers in the three time windows. The denominator of Total 2 provides the number of cells that showed significant reward dependence in one or more time windows, and the numerator indicates the number of cells that showed significant dependence on stimulus-presentation frequency in all of the windows in which it showed significant reward dependence. In a majority of the cells with reward dependence, the firing was not correlated with the presentation frequency of individual stimuli.