Time-of-day effect on a food-induced conditioned place preference task in monkeys

摘要: Time can be an important contextual cue for cognitive performance, with implications reward-associated learned behaviors such as (drug and food) addiction. So, we analyzed: (1) if marmoset monkeys develop a place preference that is conditioned to previous pairings highly-palatable food reward; (2) the response strongest when training testing times match - time stamp effect; (3) there optimal of day (morning vs. afternoon) this occurs time-of-day effect. Subjects were first habituated two-compartment conditioned-place-preference (CPP) box. Then, during six sessions held either in morning or afternoon, mixture jellybeans live mealworms was made available specific compartment. Marmosets subsequently tested preferring food-paired context at circadian matched different from training. Compared baseline levels, only subjects trained afternoon significantly longer more frequent visits shorter latency entry. Thus, rewards induced CPP response. This behavior exhibited overlapped restricted timeframe (afternoon), consistent time-stamp effect, respectively. In case, may have been internal cue. Whether due circadian-mediated oscillations memory and/or reward processes, findings applied addiction other behaviors.