Anterior cingulate cortex and ventral tegmental area activity during cost-benefit decision-making following maternal immune activation

Schizophrenia is associated with deficits in memory, behavioural flexibility, and motivation, which can result in difficulties in decision-making. The anterior cingulate cortex (ACC) and ventral tegmental area (VTA) are two brain regions that are involved in decision-making, and display dysfunction in schizophrenia. We investigated ACC and VTA activity in the maternal immune activation (MIA) model of a schizophrenia risk factor. Control and MIA rats completed a cost-benefit decision-making task in a continuous T-maze, choosing between a high cost and high reward (HCHR), and a low cost and low reward (LCLR), option. A choice reversal occurred halfway through each session. Single unit activity in the ACC and local field potentials (LFPs) in the VTA were monitored. Overall, MIA and control rats made a similar proportion of HCHR and LCLR choices across the whole recording session, suggesting similar levels of motivation. However, MIA rats made different decisions than controls during periods of increased uncertainty. This appeared to reflect memory deficits and behavioural inflexibility. MIA animals displayed an increase in ACC activity associated with cost, an increase in synchrony of ACC neurons to the VTA theta oscillation, and a decrease in coherence in the delta frequency between the ACC and VTA. These changes suggest that MIA animals may be biased towards focussing on the cost rather than the benefits of the task, a change also seen in schizophrenia. Here, however, the MIA animals may be able to increase motivation to maintain behaviour despite this change.