The time course of signals related to the sum and difference in the temporally discounted values for the left and right targets emerged immediately and nearly simultaneously in the CD and VS. This was true regardless of whether the results from these two areas were compared using the fraction of neurons showing significant effects of each variable (Figure 6A) or the proportion of the variance in neural activity attributed to a given variable (coefficient of partial determination,

find more CPD; Figure 6B). Average CPD for the difference in the temporally discounted values reached their maximum values 200 and 175 ms from the cue onset for the CD and VS, whereas the values for the sum reached their maximum 225 ms and 250 ms from the cue onset for the CD and VS, respectively (Figure 6B). In contrast, signals related to the difference in temporally discounted values for the chosen and unchosen Selleck KU57788 targets and the animal’s choice arose more slowly and gradually during the cue period (Figure 6). In both CD and VS, the latencies of the signals related to the sum and difference in the temporally discounted value for the left and right targets were both shorter than those related to the animal’s choice (Kolmogorov-Smirnov tests, p < 0.05; Figures S1A and S1B). The latencies

of the signals related to the difference in the discounted values for the chosen and unchosen targets and the animal’s choice Aconitate Delta-isomerase were not statistically different in either CD (p > 0.3) or VS (p > 0.2), and none of the signals related to the values or choice showed significant differences in their latencies between the CD and VS (p > 0.1). It has been shown that the signals related to the value of chosen option arise in the primate orbitofrontal

cortex immediately after the stimulus onset (Padoa-Schioppa and Assad, 2006), whereas other studies found that similar signals might develop more gradually in the striatum (Lau and Glimcher, 2008 and Kim et al., 2009b) as well as in the rodent frontal cortex (Sul et al., 2010). We found that the time course of these so-called chosen value signals might change depending on whether the sum of the temporally discounted values for the two targets was included in the regression model or not. In particular, when the sum of the temporally discounted values was omitted from the model, activity changes related to the temporally discounted values of the chosen target appeared much earlier (see Figures S1C and S1D). Therefore, it is important to distinguish the neural activity related to the value of the chosen target from those related to the sum of the values for alternative targets.