Restoring functional D2- to D1-neuron correspondence enables goal-directed action control in long-lived striatal circuits

Multidisciplinary evidence suggests that instrumental performance is governed by two major forms of behavioural control: goal-directed and autonomous processes. Brain-state abnormalities affecting the striatum, such as ageing, often shift control towards autonomous--habit-like--behaviour, although the neural mechanisms responsible for this shift remain unknown. Here, combining instrumental conditioning with cell-specific functional mapping and manipulation in striatal neurons, we explored strategies that invigorate goal-directed action capacity in aged mice. In animals performing instrumental actions, D2- and D1-neurons of the aged striatum were engaged in a characteristically counterbalanced manner, something that related to the propensity to express autonomous behaviour. Long-lasting, cell-specific desensitisation of D2-neurons in aged transgenic mice recapitulated the uneven D2-to D1-neuron functional correspondence observed in young mice, an effect that enabled successful goal-directed action. Our findings contribute to the understanding of the neural bases of behavioural control and propose neural system interventions that enhance cognitive functioning in habit-prone brains.