Activation of the ventral subiculum reinvigorates behavior after failure to achieve a goal: Implications for dopaminergic modulation of motivational processes.

Previous studies confirm that brief electrical stimulation of glutamatergic afferents from the ventral subiculum (vSub) can significantly enhance dopamine release in the ventral striatum for an extended duration (>20 min). However, the functional significance of this effect on motivated behavior remains to be specified. Here we tested the hypothesis that brief electrical stimulation of the ventral subiculum (20 Hz for 10 s) might increase effort expenditure for food rewards. Motivation was assessed by a progressive ratio lever pressing task, which requires continuous escalation of the numbers of lever presses to receive each subsequent sucrose pellet, eventually resulting in the failure to achieve the required ratio for a food reward. vSub stimulation at the start of a session did not affect the rate or total number of lever presses prior to reaching the "break point". In contrast, stimulation of the vSub with identical parameters on a post break point trial resulted in a significant increase in total responses. These findings demonstrate that activation of the vSub with parameters that modulate dopamine efflux in the nucleus accumbens can re-activate goal-directed behavior after failure to achieve a goal. Our data highlight a possible role for the vSub in the pathophysiology and potential treatment of motivational processes linked to psychiatric disease.