Jessica Tollkuhn

The Tollkuhn Lab seeks to understand how transient events during brain development exert lasting effects on gene expression, circuit function and, ultimately, behavior. We study how sex-specific neural circuits in rodents are established and modulated by the gonadal hormones estrogen and testosterone. The cognate receptors for these hormones are nuclear receptor transcription factors, which orchestrate modification of local chromatin environment and thus exert long-term effects on gene expression. However, the genes regulated by these receptors, as well as the specific mechanisms they utilize, remain poorly understood in the brain. This is in part because the extraordinary cellular heterogeneity of the brain complicates analysis of the small subpopulations of neurons that mediate sex-specific behaviors.

Having recently identified sex differences in both gene expression and chromatin in brain regions known to regulate sex-specific behaviors, my lab is now working to understand how hormones generate these molecular sex differences during development, through the use of biochemical, genomic, and behavioral analyses. We have developed a method that permits genome-wide analysis of histone modifications or DNA methylation in genetically defined populations of neurons. We hypothesize that these epigenetic data, combined with gene expression profiling, define the molecular signature of the critical period for sexual differentiation of the brain. Our goal is to provide a mechanistic link between the transcriptional effects of hormone signaling during development and the consequent social behaviors displayed in adulthood.