The Dorsomedial Striatum Mediates Pavlovian Appetitive Conditioning and Food Consumption

The dorsomedial striatum (DMS) is an important sensorimotor region mediating the acquisition of goal-directed instrumental reward learning and behavioral flexibility. However, whether the DMS also regulates Pavlovian cue-food learning is less clear. The current study used excitotoxic lesions to determine whether the DMS is critical in Pavlovian appetitive learning and behavior, using discriminative conditioning and reversal paradigms. The results showed that DMS lesions transiently retarded cue-food learning and subsequent reversal of this learning. Rats with DMS lesions selectively attenuated responding to a food cue but not a control cue, early in training, suggesting the DMS is involved when initial associations are formed. Similarly, initial reversal learning was attenuated in rats with DMS lesions, which suggests impaired flexibility to adjust behavior when the cue meaning is reversed. We also examined the effect of DMS lesions on food intake during tests with access to a highly palatable food along with standard chow diet. Rats with DMS lesions showed an altered pattern of intake, with an initial reduction in high-fat diet followed by an increase in chow consumption. These results demonstrate that the DMS has a role in mediating cue-food learning and its subsequent reversal, as well as changes in food intake when a choice is provided. Together, these results demonstrate the DMS is involved in reward associative learning and reward consumption, when behavioral flexibility is needed to adjust responding or consumption to match the current value.