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

Figure 6

A decrease in audiovisual-evoked CSD amplitudes was generally observed within the auditory zone of the V2L cortex in noise-exposed rats. Averaged CSD waveforms from the (a) supragranular, (b) granular, (c) infragranular upper, and (d) infragranular lower layers within the auditory zone of the V2L cortex in response to audiovisual stimuli presented at SOAs of 0, 30, and 50 ms. The black horizontal bar denotes the presentation of the visual stimulus, and the grey horizontal bar shows the timing of the auditory stimulus. The dark lines represent the group mean, and the shading represents the SEM for the noise-exposed rats (blue; ) and the age-matched controls (light grey; ). Unlike the V2L-Mz cortex, which showed an extensive increase in the audiovisual-evoked sink amplitudes across the majority of its layers following noise-induced hearing loss (Figure 4), the auditory zone of V2L (V2L-Az) showed only a modest decrease in audiovisual responsiveness which was mostly restricted to the upper-infragranular layer (). Values are displayed as .

(a) Supragranular layer

(b) Granular layer

(c) Infragranular (upper) layer

(d) Infragranular (lower) layer