The Role of Perineuronal Nets in Regulating Barrel Cortex Physiology

The Role of Perineuronal Nets in Regulating Barrel Cortex Physiology by Philip Chu Advisor: Joshua C. Brumberg, Ph.D. The ability of the brain to adapt to changing environmental conditions is regulated by genetic and environmental factors. One component of the brain extracellular matrix, a scaffold of proteins and proteoglycans, tightly ensheaths the soma and proximal processes of neurons. These Perineuronal nets (PNNs) play protective and structural roles in the brain, but also regulate plasticity and behavior. Their developmental expression is highly attenuated following sensory deprivation, or pharmacological silencing of neuronal activity. Thus, PNNs contribute to the activity dependent regulation of plasticity in the brain. Although PNNs are relatively ubiquitous in the neocortex, little is known about the degree to which they impact the physiology of the diverse neuronal phenotypes that exist there. This research focused on determining the experience dependent maturation of PNNs in different cortical layers and whether the alterations to neuronal intrinsic properties following sensory deprivation could be explained by PNN reductions. Finally, we sought to determine what aspects of intrinsic and synaptic physiology are regulated by PNNs in the hope of providing future direction for understanding their fundamental role in the neocortex. This research produced a number of key findings: 1) PNN development in the granular and supragranular layers depend more on sensory input than the infragranular layers