Abstract
Learning associations between environmental cues and rewards is a fundamental adaptive function. Via such learning, reward-predictive cues come to activate approach to locations where reward is available. The nucleus accumbens (NAc) is essential for cued approach behavior in trained subjects, and cue-evoked excitations in NAc neurons are critical for the expression of this behavior. Excitatory synapses within the NAc undergo synaptic plasticity that presumably contributes to cued approach acquisition, but a direct link between synaptic plasticity within the NAc and the development of cue-evoked neural activity during learning has not been established. Here we show that, with repeated cue-reward pairings, cue-evoked excitations in the NAc emerge and grow in the trials prior to the detectable expression of cued approach behavior. We demonstrate that the growth of these signals requires NMDA receptor-dependent plasticity within the NAc, revealing a neural mechanism by which the NAc participates in learning of conditioned reward-seeking behaviors.
Highlights
Learning associations between environmental cues and rewards is a fundamental adaptive function
By blocking NMDA receptor (NMDAR) within the nucleus accumbens (NAc) while monitoring the firing rate of NAc neurons, we reveal the dynamic contribution of NMDARs to both NAc activity and cued approach behavior at different stages of learning
During the first 2–3 days of training, animals showed a high rate of receptacle entries during the S+, S−, and the 10 s window at the end of inter-trial intervals (ITIs; Fig. 1b, left)
Summary
Learning associations between environmental cues and rewards is a fundamental adaptive function. Unexpected reward-predictive stimuli signal animals to interrupt ongoing behavior and move towards the predicted location of reward In this form of adaptive behavior, cue-reward associations invigorate approach responses. This function requires the integration of motivational and motor neural systems, which has long been thought to depend on the nucleus accumbens (NAc)[1]. High rates of exploratory behavior facilitate learning, they obscure the extent to which responses are motivated by reward-predictive cues We overcame these challenges by devising a novel individualized analysis, based on prior theoretical work[20], that allowed us to detect the first trial after which each animal showed consistent cued approach behavior. Our results identify and characterize a likely physiological substrate for the natural acquisition of cued approach behavior
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
