The nucleus accumbens is involved in the modulation of motivated behaviour by reward-associated sensory information. However, little is known about the specific nature of the nucleus accumbens' contribution to generating movement. We investigated motor encoding by nucleus accumbens neurons in rats performing a delayed response task that allowed us to dissociate the effects of sensory and motor events on firing. In a subset of neurons, firing in the delay period preceding movement was highly selective; this selectivity was tightly correlated with the direction of the subsequent movement, but not with the sensory properties of the instructive cue. Direction selectivity in this population of neurons developed over the course of the delay period, with the strongest selectivity apparent just prior to movement onset. Selectivity was also apparent in nucleus accumbens neurons during movement, such that firing showed a tight correlation with movement direction, but not the instructive cue presented nor the spatial destination of the movement. These results are consistent with the hypothesis that a subpopulation of nucleus accumbens neurons contributes to the selection and execution of specific motivated behaviours.
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