Premature vision drives aberrant development of response properties in primary visual cortex
Creators: name: Griswold, Sophie
Publisher: name: Brandeis University
Year: 2024
Subjects: cortical visual impairment
development
temporal frequency tuning
Vision

description: Over the past 60 years of neuroscience research, a vast body of work has explored the impact of impoverished or abnormal visual experience on the development of the visual circuit. As a result, we have gained a broad understanding of the parameters of visual experience that are necessary for normal development to proceed, and how this process can go wrong. Although the vast majority of this research has focused on the period following natural eye opening, very little work has examined how altering the parameters of visual experience in the time before eye opening influences development. This is not altogether surprising as these developmental periods have canonically been conceptualized as subject to very different mechanistic forces, with the period before natural eye opening being governed by spontaneous, endogenously generated activity, and period following eye opening by exogenous visual input. Much recent work has complicated this picture however, revealing that visual cortex is driven by external visual inputs prior to natural eye opening, but that this visual stimulation may play a role in driving normal development of the visual circuit. Visual stimuli have even been shown to drive the retinal waves observed across altricial mammals in the period before the onset of vision, which are known to drive development of the visual circuit. It is in this context that I wish to introduce the present study, that I hope further complicates our historically black and white conception of mutually exclusive presensory and sensory periods of development. The first section of this work presents an overview of and problematizes this paradigm, providing a review of our current knowledge of endogenously generated, experience-independent development, exogenously generated, experience-dependent development, and recent work that suggests synergy between these supposedly mutually exclusive processes. The second section provides a broad overview of the developmental of response properties in the visual circuit, from the thalamus to the higher visual areas. Finally, the third section lays out my thesis research exploring the impact of premature vision on the development of response properties in primary visual cortex.
description: The third section of this thesis demonstrates that abnormally early, patterned visual input drives aberrant development of cortical response properties. Ferret kits that had their eyes prematurely opened demonstrate significant differences across a number of receptive field and neuronal firing properties. Cells recorded in animals that had both eyes prematurely opened demonstrated increases in preferred spatial and temporal frequency, temporal frequency tuning bandwith, and baseline and maximum firing rate in comparison with controls. Cells recorded in monocular cortex contralateral to a single prematurely opened eye showed increases in preferred temporal frequency, temporal frequency tuning bandwidth, and maximum and background firing rate, in addition to the degree of suppression in response to a stimulus of a non-preferred temporal frequency. Interestingly, cells recorded in monocular cortex ipsilateral to a single prematurely opened eye also demonstrated differences in receptive field and firing properties in comparison with controls.
description: These findings suggest that exploratory neuroscience research focused on manipulating visual experience to the end of better understanding development has neglected what has been deemed the presensory period. I hope that the present study provides a springboard for further work exploring the interaction between endogenous and exogenously driven developmental processes in visual cortex.