Social Stress in Early Puberty Has Long-Term Impacts on Impulsive Action
In hamsters, individuals attacked by adults during puberty become aggressive adults. Perhaps, enhanced aggression observed as repeated attacks toward opponents is associated with a lack of impulse control. We examined impulsive action in male golden hamsters exposed daily to aggressive adults from postnatal Day 28 to 42. These animals were trained in conditioning chambers and tested during adulthood in a go–no-go task addressing action inhibition. Overall, previously stressed hamsters were less likely to inhibit a conditioned lever pressing response during no-go trials. Because this effect could be the result of an extinction impairment, additional animals were tested to evaluate their response to omission of reward associated with conditioned lever pressing. In this experiment, all animals were equally capable of inhibiting their conditioned response. The capacity to inhibit a conditioned response was further addressed by testing responses to a 60-s reward delay after lever pressing. In this case, previously stressed animals were faster to inhibit lever pressing and stopped showing a preference for the proximity of the lever. These studies show selective condition-dependent effects on lever pressing activity and support the possibility that stress in early puberty enhances impulsive action in adulthood. These experiments may be relevant to the study of mental disorders associated with early trauma in humans.