BIELAJEW, Kate
Research Activities:
The phenomenon of brain stimulation reward has been documented in a wide range of species - from goldfish to humans. Its relationship to natural reinforcers and interaction with dependence-inducing drugs has attracted neuroscientists interested in the biological basis of motivation for more than 50 years. One goal of my work, based on an anatomical framework, is to identify and quantify the relationships between different structures that support brain stimulation reward in order to understand the reward process and its implications for the impaired organism. This work exploits both histochemical (cytochrome oxidase) and behavioural adaptations of classical physiological tests (for example, refractory period) to achieve this goal.The response to rewarding brain stimulation in animals represents one among several measures used to investigate aspects of depression and is based on the idea that a major symptom of depression is a reduced capacity to experience pleasure; thus, interventions that relieve these symptoms in humans, such as antidepressant drugs, will boost reward transmission. In our laboratory, we have been refining an established animal model of depression that relies on chronic exposure to a variety of mild stressors, the result of which is believed to emulate certain features of depression in humans.
In rodents, this is indexed by measuring the thresholds for rewarding brain stimulation as well as evaluating the levels of various stress hormones. Our difficulty in obtaining reliable results led us to consider genetic differences, such as strain and gender, as explanations for our data, in addition to examining the ethological appropriateness of the behavioural measures currently in use. For example, while the most common stressors used in animal research are physical ones (for example, restraint), they may have less validity than stressors of a more social nature (for example, housing). While it is recognized that there are significant gender differences in the prevalence of neuropsychiatric disorders, animal models designed to investigate the affective states that characterize depression, for example, have relied almost exclusively on responses from male animals. A major preoccupation of this laboratory is to address this bias.
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