Control of response selection by reinforcer value requires interaction of amygdala and orbital prefrontal cortex

Goal-directed actions are guided by expected outcomes of those actions. Hum ans with bilateral damage to ventromedial prefrontal cortex, or the amygdal a, are deficient in their ability to use information about positive and neg ative outcomes to guide their choice behavior. Similarly, rats and monkeys with orbital prefrontal or amygdala damage have been found to be impaired i n their responses to changing values of outcomes. In the present study, we tested whether direct, functional interaction between the amygdala and the orbital prefrontal cortex is necessary for guiding behavior based on expect ed outcomes. Unlike control monkeys, rhesus monkeys with surgical disconnec tion of these two structures, achieved by crossed unilateral lesions of the amygdala in one hemisphere and orbital prefrontal cortex in the other, com bined with forebrain commissurotomy, were unable to adjust their choice beh avior after a change in the outcome (here, a reduction in the value of a pa rticular reinforcer). The lesions did not affect motivation to work for a f ood reinforcer, or food preferences, per se. Hence, the amygdala and orbita l prefrontal cortex act as part of an integrated neural system guiding deci sion-making and adaptive response selection.