Benign Taste Experience Enhances Cortical Response Reliability during Aversion Conditioning Towards a Novel Taste.

Learning depends on more than the association of paired stimuli in a vacuum. For example, benign experience with a taste stimulus weakens future conditioned taste aversions (CTA) to that taste-a phenomenon known as latent inhibition (Lubow and Moore, 1959). Our work has revealed a similar phenomenon in rodents whereby benign experience with tastes significantly enhances later CTA to a novel taste (Flores et al., 2016; Flores et al., 2018). This phenomenon suggests that taste experience broadly alters future taste processing in gustatory cortex (GC). To delve into this possibility, we previously have used in-vivo electrophysiology in female Long-Evans rats, recording GC activity during benign taste experience. These recordings revealed an increase in the discriminability of GC responses to both familiar and novel tastes following taste experience (Flores et al., 2022). Here, we build upon these earlier results to present a potential mechanism for this increased discriminability and salience-a reduction of cortical response variability of single-neuron responses, and enhanced coherence of ensemble responses, to the novel taste. We go on to demonstrate that the differences between pre- and post-CTA responses are greater following benign taste experience. These results suggest that benign taste experience impacts GC responses towards a novel taste pre-and post-CTA conditioning by increasing taste coding reliability at both the single-neuron and ensemble levels. Significance Statement: Animals and humans readily learn the consequences of consuming a specific taste and react by changing their behaviors. However, those changes often vary and can be influenced by previous experience. For example, our previous work has shown that inconsequential taste experiences increase the probability of a strong taste aversion. The work presented here evaluates how benign taste experience can impact cortical processing dynamics using in-vivo electrophysiology in freely behaving rats. We report that seemingly inconsequential taste experience impacts cortical plasticity. This unravels a new area of chemosensory research and may shed light on what differentiates the neural dynamics of strong and weak taste aversion learning.