Fig. 1

Fig. 1

Functional characterization of DS SINs. (A) Diagram showing dorsal view of the retinotectal projection in zebrafish larvae. Retinal ganglion cells (in yellow) send projections contralaterally from the retina to the neuropil of the optic tectum where they arborize. Periventricular neurons (PVNs, in pink) project dendrites into the tectal neuropil. Unlike PVNs, Superficial inhibitory interneurons (SINs) (cyan) have cell bodies located in the most superficial tectal neuropil and extend broad monostratified arbors into the retinorecipient layers. (B) Responses of a single SIN expressing GCaMP5G to a drifting grating stimulus. Red arrows indicate direction of grating motion, yellow arrow indicates SIN cell body and blue arrow indicates SIN arbor. White dashed line indicates skin covering the tectum. (C) Example response of a single SIN tuned to 140° directed motion. Directions of motion eliciting significant responses are indicated by arrows. Inset shows response as a polar plot. (D) Cumulative histogram of preferred directions of all DS SINs. Fitting von-Mises curves (red lines, R² = 0.8) to the population histogram reveals three normally distributed, non-overlapping populations with population peaks centered at 9°, 157°, and 264°. Each population is color-coded according to preferred direction. (E) Normalized responses of direction selective SINs, color-coded according to subtype. Responses of individual cells are shown as colored lines, mean responses shown in black. (F) Polar plots showing normalized responses of each population; mean (solid line) and dashed (±1 SD). Mean DSI, tuning bandwidth (full width half max) and preferred direction of each population relative to the body axis of the fish are shown below each polar plot.