UNSW
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| RESEARCH |
The main areas of research activity in our lab are listed below. |
1. Developmental analysis of memory
The past, and current, emphasis of our research has been on the developmental analysis of attention, learning, and memory in the rat. One issue that is of particular interest concerns the question of whether rats express learned fear in a manner appropriate to their age of training or their age of testing. That is, past research has documented that learned fear emerges in a response-specific sequence (eg., rats express fear to an aversive CS via freezing at a younger age than they express that fear via fear potentiation of startle). Our current work focuses on what happens when rats are trained at an age where they express learned fear by freezing but not by potentiated startle, and are then tested at an age where they can express learned fear with both responses. This research has direct implications not only for our understanding of how memory develops, but also for current models of the neural bases of learned fear.
Another developmental issue that we are currently investigating involves the analysis of infantile amnesia. In one part of this work we are exploring the physiological bases for the pervasive finding of more rapid rates of forgetting in young compared to adult animals. In another part of this work we are exploring various issues related to memory reactivation (ie., the apparent alleviation of forgetting produced by presenting a reminder prior to test).
We also are actively exploring developmental differences in how learned fear is inhibited. For example, in a number of recent papers we have demonstrated a marked developmental difference in the process(es) underlying extinction of learned fear in rats. This work offers unique insights into current models of extinction, as well as having substantial clinical relevance.
2. Neural analysis of memory
In this part of our research we make use of various procedures (eg., ICV infusions of CRH; temporary inactivation of specific neural structures at training or test; immunohistochemistry) to explore issues relevant to the neural bases of learned and unlearned fear. One issue that is currently receiving considerable attention concerns the effects of temporarily inactivating structures downstream from the amygdala (eg., the PnC) during fear conditioning. The question of interest here is whether these structures are involved in some way in the neural plasticity that occurs during conditioning. Another issue of current focus concerns the facilitation of extinction of learned fear by pharmacological interventions (eg., the partial NMDA agonist DCS). Advances in this particular area may have considerable application to the clinical treatment of anxiety disorders.
3. Affective modulation of the startle response
We use the startle probe procedure to explore some of the issues briefly mentioned above. We also are involved in various studies designed to expand the use of this procedure (eg., conditioned odour potentiation of startle; conditioned pleasure attenuation of startle). One reason for this strand of our research is that the startle probe procedure can be used in a variety of species (eg., mice, rats, monkeys, humans) to assess emotion. Indeed, we have recently obtained two human startle systems (Coulbourn Instruments) to expand our work on the startle probe procedure into various human populations.
4. Human conditioning studies.
We are also actively exploring similar issues in human participants. In this work, participants are first conditioned (e.g., they learn that a particular face predicts a mild shock), and then subsequently have this learned fear extinguished. In addition to various self-report measures we also record SCRs and eye gaze in these studies. One long-term goal of this work is to develop effective measures of “evaluative” conditioning. That is, even though the participant realises that the face no longer predicts the shock after the extinction session, they may still have negative feelings towards that particular face.
5. Human studies of ostracism.
Another area of interest in the lab has to do with the effects of social exclusion. In this research we explore the emotional and cognitive effects of being ostracised. A particular area of interest has to do with various post-event processes that influence the negative effects of this common type of social interaction.
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