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

As is true in humans, no two rodents prefer precisely the same tastes, and no one rodent shows precisely the same taste preference pattern forever. Here, we make use of this between- and within-animal variability to generate and test novel insights about the stability and malleability of neural perceptual coding. We used a brief-access task (BAT) to reveal both between-rat 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, we demonstrated that gustatory cortical (GC) taste response dynamics, the late part of which have been shown to reflect palatability, match that individual rats BAT preferences (evaluated almost 2 weeks prior) better than canonical preference patterns, revealing that the individual differences reflect differences in neural taste processing; this enhanced correspondence, however, links neural taste processing only to the most recent BAT session--GC palatability processing does not reflect performance in earlier BAT sessions. The finding that rats perceptual preferences shift across BAT sessions carries with it the implication that any tasting experience might change these preferences. We tested this implication by performing a second session of GC taste-response recordings--sessions in which tastes were delivered by intra-oral cannula to passive rats--and found that palatability-epoch taste responses in this later session no longer matched the most recent pre-recording BAT session. Together, these data demonstrate that every tasting experience (regardless of the method of taste delivery) changes the rats perceptual/neural processing of those tastes.