Research
Overview
The primary motivation for research in my laboratory is to understand neural mechanisms of associative learning in the mammalian brain, and most of my efforts at Drew have focused on olfactory Pavlovian conditioning in rats. In Pavlovian conditioning paradigms, an initially neutral conditional stimulus (CS) is paired with a biologically meaningful unconditional stimulus (US). Subsequent re-exposure to the CS elicits a range of physiological and behavioral responses that reflect the strength of learning. Olfactory Pavlovian conditioning is robust, long-lasting, and stimulus specific, and given that learning and expression episodes can be isolated in time, we're able to study neural mechanisms of a range of mnemonic processes including acquisition, consolidation, retrieval, reconsolidation, extinction, latent inhibition, and context dependency.
Some of the research in our lab involves olfactory fear-potentiated startle (FPS) The acoustic startle response (ASR) is set of reflexive reactions in response to loud and sudden auditory stimulation (although similar responses can be elicited by visual or tactile stimulation). ASR is highly conserved across species, making it an ideal model for comparative research, and we have conducted both rodent and human ASR experiments. Studies dating back over 50 years have shown that the ASR is typically elevated during negative affective states, such as fear, and FPS is now a widely used behavioral model for studying the neural substrates of associative learning. Techniques for olfactory FPS were first developed by Richardson, Paxinos, & Lee (2000) and refined by Paschall & Davis (2002), and our initial efforts were to validate these procedures for use in our laboratory.
Anna Blumenthal (DSSI, Summer 2008 – Fall 2009) conducted a series of parametric experiments to show that rats conditioned to fear an olfactory CS across 6-10 conditioning trials exhibited elevated startle upon re-exposure to the conditioning chamber (contextual FPS) and upon odor re-exposure (olfactory FPS). Use the links to the left to read about her work and some of our more recent work examining how the nucleus accumbens and medial amygdala contribute to this form of olfactory learning.