While estradiol, a kind of estrogen, is often considered a ""female"" hormone, it is fundamentally important for both female and male brain function. It is a hormone with a wide range of effects on the brain and human behaviour. In early life, estradiol plays an important role in the growth of brain cells and in the establishment of differences between male and female brains. In adulthood, estradiol activates both male and female reproductive behaviour. Studies also implicate estradiol in the regulation of aggression, learning and memory, muscle control and the perception of pain. Furthermore, estradiol has been shown to influence depression, recovery from stroke and brain injury, Parkinson's disease and Alzheimer's disease. Because estradiol is involved in a vast array of brain functions, many of which are critical to human health, it is important to understand how estradiol affects brain cells. Dr. Sarah Heimovics' research explores the degree to which there is plasticity in how estradiol affects the brain and behaviour. Specifically, she is investigating the effect of environmental factors, such as photoperiod, on estradiol signalling mechanisms the brain. Traditionally, estradiol has been understood to influence brain and behaviour genomically, via changes in gene expression over a relatively long timescale (days to weeks). However, a growing body of research suggestes that estradiol also has rapid (within 30 minutes), non-genomic effects. Dr. Heimovics will compare the role of genomic and non-genomic estradiol signalling mechanisms in the neural regulation of aggressive behaviour on short and long photoperiods. She is testing the hypothesis that non-genomic estradiol signalling is more pronounced on short photoperiod (as during the winter in BC), which may have implications relative to depression. The results of this research will contribute to the greater understanding of how estradiol acts on the brain, which is a critical issue for the health of British Columbians.