Figure 4
From: Viral-mediated transduction of auditory neurons with opsins for optical and hybrid activation
Cochleotopic multi-unit responses. (A) Optical fibre with bonded platinum wire. (B) Spatial response image to 1 ms optical pulses from a round-window positioned optical fibre in a neonatally AAV-injected C57BL/6 mouse. Low threshold multi-unit activity was recorded at ventral recording sites of the recording array in the inferior colliculus. Expression of ChR2-H134R-EYFP was observed in approximately 15–44% of total SGNs in the basal-mid region of the cochlea in this example, with the basal turn shown in (C). (D) Responses to apical optical stimuli were recorded in the more dorsal electrodes of the recording array in the inferior colliculus. Approximately 69% of total apical SGNs displayed ChR2-H134R-EYFP expression in this example (E). Each response image shows the spatial extent and normalised rate of multi-unit activity across the recording array which corresponds to depth in the inferior colliculus. Intensities were smoothed and normalized between spontaneous (black) and maximum rate (yellow). The white line represents the spatial tuning curve with threshold set to 30% of maximum activity. The dotted lines compare the width of activation at an equivalent level above threshold (d’ = 1 above threshold). Colour map in A applies to both response images. Minor image processing (brightness, contrast) was applied to images for representation purposes.
