Aging alters the role of basolateral amygdala in intertemporal choice

Abstract

27Aging is associated with an increased ability to delay gratification. Moreover, even when matched for 28 performance, young and aged subjects recruit distinct brain circuitry to complete complex cognitive tasks. 29Experiments herein used an optogenetic approach to test whether altered recruitment of the basolateral 30 amygdala (BLA), a brain region implicated in valuation of reward-cost contingencies, contributes to age-31 dependent changes in intertemporal decision making. BLA inactivation while rats deliberated prior to choices 32 between options that yielded either small, immediate or large, delayed rewards rendered both young and aged 33 rats less impulsive. In contrast, BLA inactivation after choices were made (during evaluation of choice outcomes) 34 rendered young rats more impulsive but had no effect in aged rats. These data define multiple, temporally-35 discrete roles for BLA circuits in intertemporal decision making and implicate altered recruitment of BLA in the 36 elevated preference for delayed rewards that is characteristic of advanced age. 37 38 39 Keywords 40 aging, basolateral amygdala, optogenetics, decision making, delay discounting, impulsive choice 41 42 Abbreviations 43 basolateral amygdala (BLA); Fischer 344 x Brown Norway hybrid (FBN); intertrial interval (ITI) 44 45 Impact Statement 46 Basolateral amygdala (BLA) performs multiple, temporally-discrete functions during intertemporal decision 47 making. Differential engagement of BLA contributes to the enhanced ability to delay gratification that is 48 characteristic of advanced ages. 49 50