1). We also found that the number of neurons significantly modulating their activity according to various types of temporally discounted values was largely unaffected when the reaction time and peak

velocity of the saccade were included in the regression model (see Table S1 available online). These results suggest that the signals related to the temporally discounted values for the two targets are combined differently in the caudate Kinase Inhibitor Library nucleus and ventral striatum. In the caudate nucleus, neurons often encoded the difference between the temporally discounted values of the two alternative targets, suggesting that the activity might increase with the value of one target and decrease with the value of the other target. In contrast, neurons in the ventral striatum largely encoded the sum of temporally discounted value of the two targets, suggesting that their activity might be influenced similarly by the temporally discounted values of both targets. To test these predictions Selleck A-1210477 more directly, we applied a regression model that includes the temporally discounted values of the leftward and rightward targets (model 2; see Experimental Procedures). For the CD neuron

illustrated in Figure 2, this analysis found that the regression coefficient for the temporally discounted value of the left target was significantly negative (t test, p < 10−15), whereas the regression coefficient

for the right target was significantly positive (p < 0.05). We found that the number of neurons showing the significant effects of temporally discounted values for both targets was nine for both CD and VS (Figure 4A). In both areas, this was significantly more than expected when the activity of each neuron was influenced by the temporally next discounted values of the two targets independently (χ2 test, p < 0.05). Furthermore, among the neurons that significantly modulated their activity according to both variables, six neurons in the CD but only one neuron in the VS showed opposite signs in the corresponding regression coefficients. This difference was statistically significant (χ2 test, p < 0.05), confirming the results described above that the neurons in the CD tended to encode the difference in the temporally discounted values of the two alternative targets more frequently than the VS neurons. We also found that the regression coefficients associated with the temporally discounted values of the left and right targets were significantly more positive than the values obtained from the permutation test (see Experimental Procedures) in the VS (p < 10−4), but not in the CD (p = 0.58; Figure 4A).