Week-old chicks quickly learn to peck colored beads when reinforced by food rewards. In binary choice tests, the trained chicks made choices based on anticipated values of foraging efficiency. Two forebrain regions proved to be involved in the anticipation, i.e., ventral striatum ⁄ nucleus accumbens complex (basal ganglia) and arcopallium (an association area of lateral forebrain). Localized lesions of the basal ganglia caused an impulsive choice away from a long waiting time. On the other hand, lesions of the association area caused an impulsive choice away from a long consumption time. These results suggest that 1) chicks make choices based on foraging efficiency, in which sum of the waiting time (or time-to-reward) and the consumption time (or work cost) serve significant denominator, and 2) these two time domains have distinct neural substrates, thus are assumed to be neuro-ecologically distinct factors.
