Speaker: Adam Stinchcombe
Abstract. The suprachiasmatic nucleus (SCN) has long been known as the site of the central circadian pacemaker in mammals. In this talk, I will present two of my approaches to and results from studying this brain region.In the first approach, I directly simulate the electrophysiology of all of the neurons in the SCN, their electrical connections, and the photic input they receive. Simulating every spike in all 20,000 neurons requires massively parallel hardware and carefully designed numerical methods. After incorporating recently acquired experimental data, we learned from the simulation that the SCN is able to process light information beyond that needed to regulate the clock. This form of sub-conscious vision interestingly depends on the electrical connections among neurons being a small-world network. In mammals, a genetic negative feedback loop allows individual neurons to keep track of time. These oscillators are noisy and must synchronize to function as an accurate clock. The oscillator population must also entrain to photic input. In my second approach to studying the SCN, I simulate these processes with a novel numerical method based on a particle discretization of a non-local partial differential equation. This simulation has given us insight into the significant differences between population and individual entrainment to light signals. This should benefit trans-meridian travelers and shift workers.