Figure 1. OFC neurons signal task context.

A) Task design in [24•]. Subjects made choices between pairs of presented pictures. On effort trials, they had to lift a lever and hold it for 1.5-s to earn the reward. On delay trials, they simply had to wait for a specific delay before they received the reward. The amount of reward they received, the force to lift the lever and the length of delay varied depending on the picture they chose. Effort and delay trials were intermingled in the same session. B) Percentage of neurons that were identified in OFC, the anterior cingulate cortex (ACC) and the cingulate motor area (CMA), using stepwise regression, as encoding specific variables during the first half of the choice epoch. For OFC, the 3 variables that were most frequently encoded are shown. The horizontal dotted line represents chance levels of neuronal selectivity. Red bars indicate that the proportion of selective neurons is significantly higher than the average proportion of selective neurons in the fixation period, assessed using a binomial test at p < 0.05, with a Bonferroni correction for multiple comparisons. C) Time course of activity encoding the type of decision for effort-preferring and delay-preferring neuronal populations. Each plot shows the mean firing rate relative to baseline ± S.E.M. The grey shading illustrates the 500-ms epoch used for analysis which is centered on the mean latency at which the information is encoded in each area. The blue numbers indicate the number of neurons included in each plot. OFC neurons were modulated primarily by delay- but not effort-based decisions. This is consistent with studies showing effects of OFC lesions on delay- but not effort-related decision making in situations where there is no bridging cue between the choice point and the delayed reward [63,64]. Adapted from [24•].