To understand the neural basis of cognition and behavior, we need to understand the mechanisms by which neurons gate and modify each other's actions. Recent work by Dr. Chance has introduced and characterized a cellular mechanism for gain modulation, a phenomenon in which one input acts as a "volume control", or gain control, of neuronal responses to static inputs. However, because the brain is inherently dynamic, it is crucial to describe the dynamical aspects of this mechanism of gain modulation. Dr. Chance and members of her laboratory will record the electrophysiological responses from neurons in slices of rat visual cortex to measure the temporal dynamics of gain modulation and describe how the temporal dynamics of neuronal responses are affected by such modulation. Once the temporal dynamics of the gain modulation mechanism are characterized, Dr. Chance's laboratory will construct detailed computational models of the circuitry of the primary visual cortex that incorporate the data characterizing the mechanism for gain modulation. The model will then be used to test the hypothesis that the gain control mechanism is responsible for some well-known non-linear response properties of visual cortical neurons, such as response normalization, that are observed in vivo but which cannot be explained by traditional feed forward models. Dr. Chance's research thus combines experimental and computational techniques to study how gain modulation arises at the cellular level and to explore its function at the level of neural circuits in primary visual cortex. This research will not only contribute to the knowledge of how visual processing works, but will lay the foundation for uncovering mechanisms underlying later stages of cortical processing and phenomena, such as attention. Dr. Chance is a young female investigator serving as a role model for young women to become, or stay, involved with computational approaches to neurobiology, including a female graduate student who will be mentored on this project.
