Frontostriatal systems comprising connections between ventral medial prefrontal cortex and nucleus accumbens subregions differentially regulate motor impulse control in rats.

Abstract

Deficits in impulse control are prevalent in several neuropsychiatric disorders that are based on impaired frontostriatal communication. The ventral medial prefrontal cortex (vmPFC) and the nucleus accumbens (NAc) are key substrates of impulse control in rats. The NAc core and shell are considered to be differentially involved suggesting a functional distinction between the connections of the vmPFC and particular NAc subregions concerning impulse control. In the present study, simultaneous inactivation of the rats' vmPFC and NAc core or shell by contralateral microinfusion of the GABAA receptor agonist muscimol was used to investigate their relevance for impulse control in the five-choice serial reaction time task (5-CSRTT). Disconnection of the vmPFC and NAc shell produced specific impairments in inhibitory control, indicated by significantly increased premature responding and an enhanced number of time-out responses, closely resembling the effects of bilateral inactivation of either the vmPFC or NAc shell previously reported using the same task. In contrast, disconnection of the vmPFC and NAc core only slightly increased the rate of omissions and latency of reward collection indicating attentional and motivational deficits. Our results extend previous findings indicating the functional specialisation of frontostriatal networks and show a differential contribution of specific vmPFC-NAc connections to behavioural control depending on the NAc subregion. We conclude that the regulation of impulse control in rats requires an intact connection between the vmPFC and the NAc shell, while the vmPFC-NAc core projection seems to be of minor importance.