Chronic social stress induces isolated deficits in reward anticipation on a neuroeconomic foraging task

Abstract

Measuring reward anticipation distinct from other aspects of reward value, including costs required to obtain a reward or the intrinsic hedonic value of consuming the reward itself, can be difficult to disentangle. Here, we show that mice trained on a self-paced neuroeconomic foraging task convey reward anticipation via differentially invigorated travel times between uniquely flavored feeding sites separate from willingness to wait, consummatory behaviors, or place preferences measured within the same trial. Following exposure to chronic social defeat stress, we found that only stress-susceptible but not stress-resilient mice revealed deficits in this metric after consuming but not after rejecting a reward on the previous trial, indicating that blunted anticipation in these animals is state-dependent, or punctuated by recent reward receipt. After increasing economic pressure and task demands, locomotion was globally invigorated and, in turn, masked stress-related deficits in reward anticipation. These findings suggest that the ability to detect changes in specific aspects of motivational deficits associated with depression and other stress-related disorders depends on an interaction between the state of an individual and environmental circumstances.