Allison Murphy¹, Kristina Nielsen¹; ¹Johns Hopkins University

Binocular disparity, the difference in position of an image on each retina, is an important cue the brain uses to generate perception of depth. Several areas of the brain, including primary visual cortex (V1), contain neurons tuned for binocular disparity. While the encoding of disparity in V1 has been studied in adults, less is known about how it develops in younger animals. However, this is important for understanding the development of stereoscopic vision as well as how it may be disrupted in disorders such as amblyopia. The ferret is a highly visual animal and undergoes much of its development postnatally, making it an ideal model for studying the development of the structure and function of the visual brain. Despite the prevalence of the ferret as a model of visual system development, little is known about its capacity for stereoscopic vision compared to other animal models. To address this, we performed electrophysiological recordings in primary visual cortex (V1) in ferrets aged postnatal day 30 to adult. Utilizing a mirror stereoscope, we presented binocular and monocular stimuli and systematically varied the direction and binocular disparity of drifting gratings. We analyzed single-unit responses to assess the joint development of ocular dominance, direction tuning, and binocular disparity tuning across several developmental timepoints. We find that disparity-tuned neurons are present in V1 as early as postnatal day 30, although the proportion of tuned neurons and quality of tuning varies over time. These results are a first step in establishing the ferret as a developmental model for stereoscopic vision.

Acknowledgements: 1R01EY035807