Compensatory Plasticity in the Lateral Extrastriate Visual Cortex Preserves Audiovisual Temporal Processing following Adult-Onset Hearing Loss

Figure 1

Pharmacological silencing of the V2L cortex disrupts audiovisual temporal acuity in rats. (a) An overview of both the TOJ task and the SJ task that were used to screen rats for their audiovisual temporal acuity. Across several stages, rats were trained to select the right or left feeder trough depending on the stimulus condition presented (i.e., TOJ task: auditory- trough and visual- trough; SJ task: trough and trough). (b) Schematic of the location of the drug infusion cannulae reconstructed from histological sections for each of the rats trained on the TOJ (blue squares) or the SJ task (green circles). (c) Behavioral performance on the TOJ task was plotted as the proportion of trials perceived as visual first for test sessions completed following the infusion of aCSF (black circles) and muscimol (blue squares). Overall, there was a rightward shift in the TOJ psychometric curve when muscimol was infused into the V2L cortex, with a significant decrease in trials perceived as visual first at SOAs of 40 and 200 ms (), as well as a modest decrease at an SOA of 0 ms (). (d) For the SJ task, behavioral performance was plotted as the proportion of trials perceived as synchronous for test sessions completed following an infusion of aCSF (black circles) or muscimol (blue squares). Following an infusion of muscimol, a greater proportion of SJ trials was perceived as synchronous at SOAs of 40 and 200 ms () and a trend towards an increase was observed at an SOA of 100 ms (). Results are displayed as for the rats trained to perform the TOJ () and SJ () tasks.

(a) Behavioral tasks

(b) V2L injection sites

(c) TOJ psychophysical curves

(d) SJ psychophysical curves