Grant: Doctoral Research Award: Canada Graduate Scholarships

Depression is a debilitating illness affecting 20% of the population that is characterized by depressed mood and disrupted cognition. Compared to males, females are twice as likely to develop depression and experience more severe cognitive symptoms. One such cognitive symptom is negative cognitive bias, the interpretation of neutral situations as negative. Depression is associated with changes in brain activation. We have found that following chronic stress, both male and female rats display depressive-like behaviours; however, the areas of the brain that are activated during negative cognitive bias are different. This suggests that negative cognitive bias may have different causes in females vs. males and might need to be treated differently between the sexes. Negative cognitive bias can be measured using a task developed in the Galea lab. Rats are trained to associate one environment with an electric shock and another with no shock. Rats are then tested in a neutral environment and their fear response is recorded. Increased fear behaviour indicates negative cognitive bias. To determine if altering activity in the brain areas that are most important for negative cognitive bias can be used as a treatment, we will block activation during testing and see if the fear response changes. We expect to see differences in fear responses between females and males, and between animals that had activation blocked during testing and untreated animals. There is enormous need for treatments that address both the mood and cognitive symptoms of depression. The proposed research will examine sex differences in brain areas activated during stress-induced negative cognitive bias and explore how stopping this activation can prevent negative cognitive bias. Our results will provide valuable information to help develop new treatments for depression in both females and males.