Distinct mechanisms of visual and sound adaptation in the cat visual cortex

Sensory areas exhibit modular selectivity to stimuli, but they can also respond to features outside of their basic modality. Several studies have shown cross-modal plastic modifications between visual and auditory cortices; however, the exact mechanisms of these modifications are yet not completely known. To this aim, we investigated the effect of 12 minutes of visual vs. sound adaptation [forceful application of a non-optimal stimulus to a neuron(s) under observation] on the infra- and supra-granular primary visual neurons (V1) of the cat (Felis catus). Previous reports showed that both protocols induced orientation tuning shifts, but sound increased the bandwidths. Here, we compared visual vs. sound adaptation effects, specifically analysing the raw tuning curves by computing the area under the curve (AUC) on a trial-by-trial basis. We report that sound adaptation elicited broader tuning curves accompanied with increased variance in the supra- and infra-granular layers, compared with visual adaptation. These findings suggest unique modulation of dendritic structure by distinct adaptation protocols, resulting in disparate tunings. We suggest that broader tuning curves after sound adaptation may keep the visual cortex prepared across a spectrum of abstract representations that match with visual stimuli.