Research.

Our main area of research interest involves the experimental analysis of memory. Because this is such a broad issue, we are able to explore it from a variety of perspectives.


From Baker et al., 2017

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.


From Kim et al., 2011

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.

 

From Baker et al., 2014

 

3. Adolescence

We explore fear expression and inhibition in adolescents, with a focus on understanding the different characterstics of the fear system during this period of development. In addition to exploring the effects of stress during adolescence, we also examine behavioural, pharmacological, and dietary effects on fear regulation in adolescents.

 

From Callaghan, Cowan, & Richardson (2016)

4. Early-life stress

Here we investigate the effects of early-life adversity on fear regulation in the developing rodent. As a part of this line of research we are exploring the possible beneficial effects of probiotics in regards to reducing, and perhaps eliminating, the adverse consequences of early-life stress.

 

 

From Kan, 2017

5. Transgenerational effects

The effects of early-life stress ripple through time and affect individuals not directly exposed to it. For example, the offspring of male rats that had been exposed to early-life stress as an infant exhibit a behavioural phenotype strikingly similar to their father (i.e., an accelerated maturation of fear expression). In addition, the subsequent offspring of an adult female that had been repeatedly separated from her previous litter behave in the same altered way, in regards to fear memory and extinction, as did their older siblings who had actually been directly exposed to the early-life stress. These two routes are referred to as “vertical” and “horizontal” transgeneration transmission.