Molecular Underpinnings of Human Brain Evolution and Cognition at Cellular Resolution

Molecular and functional characterization of the human brain is challenging due to its experimental inaccessibility. Most of our understanding about human brain function relies on the assumption that biological processes uncovered in model organisms are conserved in humans. Comparisons of the humanii brain with non-human primate brains offer to both uncover the novelties in human brain evolution and better evaluate the insights obtained from model organisms about human brain function. To achieve this, highthroughput sequencing methods on post-mortem brain tissues provide a rewarding readout to understand human brain evolution at the molecular level. In addition to their use in comparative studies, these technologies were also utilized with a hope to understand molecular underpinnings of measurable human brain activity metrics. During my dissertation, I read relevant literature extensively (Chapter 1) and sought to understand human-specific epigenomic and transcriptomic changes at cellular resolution in the cortical brain (Chapter 2). Additionally, after in-depth analysis of many human brain single-nuclei RNA-seq datasets, I found a pervasive ambient RNA contamination problem, and devised in silico solutions to tackle this problem. My efforts improved the analytical approach in the field as well as in my research (Chapter 3). I have also been involved in efforts to identify transcriptomic correlates of brain activity in human subjects (Chapters 4-5). After detailing these efforts, I discuss the implications of these findings, weigh their impact on our understanding of human brain function and offer ideas for further research (Chapter 6).