Research
Understanding the mechanisms of neuroplasticity as related to learning and memory is fundamental to our understanding of the causes of a variety of cognitive disorders. Our laboratory addresses these issues by using a rodent model of spatial navigation to investigate the dynamic responses of single neurons in the brain, as well as the complex interactions between cells located in different memory-related structures. These studies employ techniques involving recording extracellular signals from many cells simultaneously as animals perform memory tasks. Our studies have examined many processes that contribute to successful and adaptive navigation including the evaluation of sensory input during active locomotion (e.g. Mizumori & Williams, 1993; Cooper et al., 1998), the integration of current sensory information with past knowledge about an environment (e.g. see Mizumori et al., 1999a,b, Cooper et al., 2001) and with internal state information (e.g. Leutgeb & Mizumori, 1999, 2002), and the behavioral implementation of highly processed spatial information (e.g. Mizumori et al., 1999b, in press). More recently, we consider these processes in terms of the flexibility of underlying neural representational systems during shifts in cognitive strategy or task demands (Smith & Mizumori, 2006; Eschenko & Mizumori, 2007). Based on this work, we currently focus much of our research effort on understanding how contextual features of a learning situation modify properties of neural representations, and how neuromodulators such as dopamine come to bias the efficiency of different information processing systems such as the frontal cortex, hippocampus, and striatum (e.g. Mizumori et al., 2004; Smith & Mizumori, 2006, 2007; Mizumori, 2007; Gill et al., 2007; Gill & Mizumori, 2006; 2007).
Recent Collaborations
Our efforts to understand the role of dopamine in memory has recently been extended to include behavioral and neurophysiological analyses in genetically engineered mice in collaboration with Dr. Richard Palmiter (palmiter@u.washington.edu; Robinson et al., 2004).
A neural systems analysis of learning and memory has recently been applied to a very different form of learning, conditioned taste aversion. Together with Dr. Ilene Bernstein (ileneb@u.washington.edu), we study plasticity of neural representations within an established neural circuit that mediates conditioned taste aversions.
The Mizumori and Bernstein laboratories also work together to extend investigations of learning and memory from the single cell level to the examination of neural activity across large populations of cells. This has been accomplished by incorporating immediate early gene analyses in our behavioral and neurophysiological research program (e.g. Gill et al., 2007).