Experience-induced drift in the neural coding of individual differences in perception

Abstract

As is true in humans, no two rodents prefer precisely the same tastes. Furthermore, no one rodent keeps precisely the same taste preferences forever. Here, we have made use of this between- and within-animal variability to generate and test novel hypotheses about the stability and malleability of neural perceptual coding. We used a brief-access task (BAT) to reveal both individual differences in taste preferences and shifting preferences within individual rats (quantified in terms of lick bout lengths). We moved on to show that these phenomena are not simply random variation: first, by demonstrating that gustatory cortical (GC) taste response dynamics, the late part of which reflect palatability, match that individual rat's BAT preferences (evaluated almost 2 weeks prior) better than canonical preference patterns; that is, individual differences in preferences reflect differences in neural taste processing. This match, however, links neural taste processing only to the most recent BAT session--GC palatability processing does not reflect performance in earlier BAT sessions. We hypothesized that any tasting experience might impact taste processing (i.e., not just BAT licking), and tested this hypothesis by adding a second session of GC taste-response recordings; palatability-epoch taste responses in this later session no longer matched the most recent pre-recording BAT session, demonstrating that responses following the first electrophysiology session had changed. Together, these data demonstrate that every tasting experience (regardless of the method of taste delivery) changes the rat's processing of those tastes.