Neural mechanisms of visual cortex development and plasticity in humans and animal models

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Development of the visual cortex plays an important role in controlling the maturation of vision. It is well-known that the mature adult male visual cortex is substantially larger than the female, but few studies have addressed whether there are sex differences in how the visual cortex develops. Although studies of sex differences in other areas of the brain have shown that the female brain is not merely a smaller version of the male, little is known about the neurobiological mechanisms that differentiate the female and male visual cortex. We know even less about experience-dependent biases that might lead to sex differences in the visual cortex. Vision is the dominant sense in humans, and the primary visual cortex is the first step in a dynamic hierarchy of more than 30 cortical areas that process visual information. Sex differences in the primary visual cortex can ripple through that system, affecting functions from acuity to reading. In my laboratory, our long-term goal is to understand how the visual cortex changes across the lifespan and the role that visual experience plays in altering cortical structure and visual function. For example, we now know that the development of the human visual cortex extends into the fourth decade of life. It seems likely that development and experience may have different effects on female and male visual cortex. The main objective of this application is to compare age, sex, and experience-dependent changes in the visual cortex to identify when sex differences emerge and if early experience affects those differences. Our approach includes animal models and studies of human brain development using a library of postmortem tissue samples that cover a range of ages from birth to old age. We are interested in following up on our pilot studies that found neurobiological and visual differences in male and female animals, with new studies to determine the precise features that control those sex differences. We will also use some new and exciting tools for analyzing big data to unpack the complex changes that occur during brain development. The aims of this research are to 1) Classify development of plasticity markers in visual cortex and test for sex differences; 2) Measure cortical neurosteroids and assess their influence on the development of visual cortex; 3) Assess the impact of early visual experience on sex differences in vision and visual cortex. We have designed studies to address these aims in humans and animal models and assess sex differences using modern data analytics. The results will address the influence of sex, age and experience on the neurobiological development of the visual cortex. The knowledge gained from these studies will advance fundamental NSE questions about sex differences in the developing brain. An important benefit of this work, and a priority for my laboratory, is creating a diverse and inclusive training environment to support the next generation of Canadian neuroscientists.