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Presidential Professor of Zoology
Phone: (405)325-5653
Fax: (405)325-6202RM/Lab:RH410
Sullivan Lab web page
Current Research Interests and Subject Areas Available for Graduate Research
My research explores behavioral and neural plasticity during development. I have two research lines, one involving basic research in rats and the other more clinically directed in humans. In both research lines, I use sensory stimuli (olfactory and somatosensory) within the context of the mother-infant dyad to assess behavioral and neural plasticity.
The basic research has focused on how infant rats learn about their mother. The central nervous system of altricial infants is specialized for optimizing attachments to their caregiver. This heightened learning is expressed behaviorally as an enhanced ability to acquire learned odor preferences and a decreased ability to acquire learned odor aversions (Moriceau, Wilson, & Sullivan, in prep; Sullivan, Landers, Yeaman & Wilson, 2000; Sullivan, Stackenwalt, Nasr, Lemon & Wilson, 2000). It appears as though there are at least two brain structures underlying the neonatal rat's sensitive period for heightened odor learning; the noradrenergic locus coeruleus and the amygdala.
Locus coeruleus - Association of an odor with Locus Coeruleus stimulation is sufficient to produce early odor preference learning, while lesions of the Locus Coeruleus prevent this learning (Sullivan et al., 1992; Sullivan et al., 2000). Furthermore, maturation of the Locus Coeruleus physiologically around postnatal day 10 (PN10; Nakamura, Kimura, Sakaguchi, 1987; Nakamura & Sakaguchi, 1990) coincides with the termination of the learning sensitive period (Sullivan et al., 1995). Finally, and perhaps most interestingly, preliminary results suggest that pharmacological manipulations of the mature locus coeruleus that re-instate immature locus coeruleus function restore sensitive period behavioral learning (Moriceau et al., in prep). Given these observations, we hypothesize that the Locus Coeruleus is responsible for enhanced odor preference learning and that maturation of the Locus Coeruleus signals the termination of the sensitive period for this behavioral phenomenon.
Amygdala - Our more recent data suggest that the lack of amygdala participation in odor-shock conditioning underlies the infant's difficulty in learning neonatal odor aversions (Sullivan et al, 2000). In adults, the amygdala is strongly implicated in emotional memories, particularly fear (Davis, 1997; Fanselow & LeDoux, 1999; Fendt & Fanselow, 1999; McGaugh, Cahill & Roozendall, 1999). However, the infant rat shows some unique learning characteristics. For example, a very broad spectrum of stimuli can function as reward in infants to produce a learned odor preference: specifically milk but even painful stimuli such as tail pinch or moderate shock (Camp & Rudy, 1988; Johanson & Hall 1979; Rudy & Cheatle, 1979; Sullivan, Brake, Hofer & Williams 1986a; Sullivan, Hofer & Brake, 1986b). After the sensitive period (around PN10), the range of stimuli effective in odor preference conditioning is greatly narrowed and a more typical relation appears - e.g., milk retains its ability to produce an odor preference, while shock now produces a learned odor aversion. Our recent work has demonstrated that the appearance of learned odor aversions coincides with amygdala participation in odor-shock conditioning. Specifically, odor-shock (0.5mA) association prior to PN10 fails to activate the amygdala (14C-2-DG uptake) and results in learned odor preferences, while odor-shock association after PN10 activates the amygdala and results in learned odor aversions. Additionally, previous work from our lab suggests that amygdala lesions during the sensitive period have very little influence on behavior (Sullivan & Wilson, 1993). Interestingly, fear to naturally fearful odors also emerges around PN10 (Takahashi 1994a; Takahashi & Rubin, 1993; Wiedenmayer & Barr, 1998).
Our human research has shown that newborn infants learn about odors and maternal odors modulate infant behavior. We are currently assessing whether odors can be used as a clinical tool.
Graduate student projects' include the role of opiates in neonatal learning (Tania Roth), the role of corticosterone in neonatal learning (Stephanie Moriceau) and the role of NE in neonatal odor-shock conditioning (Geoff Stackenwalt).
To learn more about this research, visit the Sullivan lab web page.
B.S., City University of New York - Brooklyn College
Presidential Professor, 2003
Member, Oklahoma Center for Neuroscience
Selected publications:
Sullivan, R.M., Landers, M., Yeaman, B. and Wilson, D.A. (2000) Good memories of bad events in infancy: Ontogeny of conditioned fear and the amygdala. Nature, 407:38-39.
Sullivan, R.M., Stackenwalt, G. Nasr, F., Lemon, C. and Wilson, D.A. (2000) Association of an odor with activation of olfactory bulb noradrenergic B-receptors or Locus Coeruleus stimulation is sufficient to produce learned approach response to that odor in neonatal rats. Behavioral Neuroscience, 114:957-962.
Hofer, M.A. and Sullivan, R.M. (2001) Towards a neurobiology of attachment. In: C.A. Nelson and M. Luciana (Eds.) Developmental Cognitive Neuroscience, pp599-616.
Sullivan, R.M. (2001) Unique characteristics of neonatal classical conditioning: The role of the amygdala and locus coeruleus. Integrative Physiological and Behavioral Science, 36:293-30.
Sullivan, R.M. and Wilson, D.A. (2003) Perspective: Molecular biology of behaviorally relevant memory. Learning and Memory, 10:1-4.
Sullivan, R.M., Landers, M., Fleming, J., Young, T. and Polan, J. (2003) Characterizing the functional significance of neonatal rat vibrissae. Somatosensory and Motor Research, 20:157-162.
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