Using behavior to interrogate neural circuit function
We are interested in how neural circuits control behavior and the psychological processes underlying behavior. Our research draws on molecular genetics and experimental psychology. Molecular genetic tools are used to selectively manipulate neural circuits in mice. Experimental psychology is used to understand how and why these manipulations alter behavior. We are using these approaches to investigate several research questions.
Adult hippocampal neurogenesis
Adult hippocampal neurogenesis is conserved across many, if not all, mammalian species. And adult-born neurons appear to have important functional effects. Changes in the rate of adult neurogenesis correlate with clinically important variables. For instance, psychosocial stress potently suppresses hippocampal neurogenesis, while exercise, environmental enrichment, and virtually all antidepressant treatments stimulate adult hippocampal neurogenesis. Using targeted, inducible genetic manipulations in mice, combined with behavioral analysis, we are answering questions such as: Which aspects of hippocampus-dependent memory and behavior require adult neurogenesis? Are adult-born neurons functionally differentiated from developmentally-generated neurons? If so, what properties of adult-born neurons confer this unique function? Do the functions of adult-born neurons differ across the dorsal-ventral axis of the hippocampus?
Hippocampus and emotional memory
Context memories are multimodal memories of time and place that can be used for different purposes. A context can acquire emotional valence, such as in contextual fear conditioning, where a context acquires the ability to elicit fear. Or a context can help disambiguate the meaning of other stimuli, while remaining neutral itself. For instance, if one is driving down the highway at 80 mph, the sound of a siren may induce fear or anxiety; but if one is sitting in the living room, the siren is not likely to elicit an emotional response. The context (highway versus living room) determines how the siren is interpreted. We are interested in how these different uses of context memory are represented in the brain. Can they be localized to different subregions or longitudinal segments of the hippocampus? How do the neural representations change over time?