Download or read book Effects of Early Vision Loss on Neural Coding of Tactile Stimuli in Primary Somatosensory Cortex written by Deepa Lakshmi Ramamurthy and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The developing brain is shaped by both genetic and activity-dependent mechanisms. Despite genetic constraints, the neocortex has the capacity to be constructed based on the particular sensory milieu experienced by an animal over the course of development. The ratios of incoming inputs from different sensory systems to the developing neocortex can be altered either by changes in the external environment of the animal or by modifications to its sensory receptor arrays. The large majority of studies that examine the role of sensory inputs in the development of the neocortex have focused on changes that occur within the sensory system in which inputs have been altered, removed or enhanced. Far less is known about the effects of such manipulations on the cortical function of the remaining, intact sensory systems. The overarching goal of the studies presented here is to investigate the effects of complete loss of vision early in life on the neural coding of stimuli in a spared sensory modality, specifically, touch. The short-tailed opossum (Monodelphis domestica) was used as the animal model in these studies because the highly immature state of its nervous system at birth allows for targeted extrauterine manipulations at specific time points relative to early developmental milestones. First, we characterized the responses of single neurons in primary somatosensory cortex (S1) of sighted opossums to simple tactile stimuli in the form of individual whisker deflections. We found that S1 neurons were selectively responsive to a small fraction of whiskers on the mystacial pad and receptive fields tended to have a horizontally elongated shape, similar to barrel cortex neurons in mice and rats. Next, we tested for differences in the representation of tactile stimuli in S1 of early blind opossums. Single neurons in early blind opossums were less sensitive, but more selective to whisker stimuli, in comparison to sighted opossums. As a result of this improved spatial resolution for whisker touch, the location of whisker stimuli could be decoded with better accuracy from the responses of neurons in early blind versus sighted animals, particularly along the horizontal axis, the primary axis of natural whisker movements. Finally, by rearing sighted and early blind opossums in a three-dimensionally enriched environment, we found evidence that alterations in receptive fields of S1 neurons following early blindness could be shaped by tactile experience, leading to an even greater enhancement of neuronal tuning along the horizontal axis.