Male spontaneously hypertensive rats demonstrate reduced goal-directed control and difficulty updating previous learning

Abstract

Habitual control of repeated behaviours is adaptive because it can allow routine behaviours to continue under conditions where cognitive capacity is limited or burdened. However, the impact that cognitive demand has on behavioural control has not been thoroughly studied in animal models of habits. This study used a strain of rats—spontaneously hypertensive rats (SHRs)—that have known cognitive deficits to investigate their ability to update their behaviour following changes to outcome value, instrumental contingency, and the predictions of stimuli across multiple tasks. An outcome devaluation task was used to test whether instrumental performance was sensitive to changes in outcome value. While SHRs reduced responding for the devalued outcome, this effect was dampened relative to Long Evans controls. An omission contingency was then introduced and SHRs were unable to adapt their responding when a once reinforced response now prevented the delivery of a free outcome. A Pavlovian devaluation task found that SHRs were insensitive to devaluation and entered the magazine upon presentation of a reward-predictive stimulus, regardless of whether the stimulus predicted a devalued or non-devalued outcome. Finally, SHRs were found to be slower than Long Evans to inhibit initial learning when a stimulus that initially predicted food pellets was no longer reinforced. Collectively, these tasks help better characterize the behavioural capabilities of SHRs and extends our understanding of how limited cognitive capacity relates to expression of habitual behaviour.