Grant: Discovery Grants Program - Individual

Behaviours that are oriented towards attaining a specific target (goal-oriented behaviours) are strongly influenced by changes in the organism's internal state, such as those induced by deprivation conditions. For example, it is well known that food intake is controlled both by an internal drive for "energy homeostasis" and by the innate stimulus properties of food (e.g., taste, texture). In line with these findings, my team has demonstrated a robust augmentation of drug seeking in chronically food restricted, abstinent, rats with a history of heroin or cocaine self-administration. These latter findings highlight the capacity of environmental challenges to interact and affect brain system that are involved in both natural- (for example, food) and drug-rewards-directed behaviours. Using psychoactive drugs as reward to study neuronal circuits that control reward seeking has several important advantages. It avoids long- and short-term changes due to the consumption of natural rewards (e.g., satiety), and it largely bypasses the peripheral sensory pathways. The latter allows for a more direct investigation of reward-related circuits. Surprisingly, although a caloric restriction diet is clearly a stressful condition, our studies indicate that the effect of chronic food restriction on drug seeking is not mediated by activation of stress-related brain systems. The long-term goal of my research is to determine how deprivation-induced adaptations in the relevant neuronal systems can modulate motivation and behaviour. The focus of the current proposal is on two powerful incentives, drugs of abuse and food. To that end, I plan to study the neuronal systems and pathways that are known to be involved in natural and drug reward seeking in rats (for example, dopaminergic and glutamatergic pathways), and investigate less obvious pathways that have recently been identified as critical components in the control of goal-directed behaviours. My research involves the use of sophisticated behavioural procedures, such as palatable food and drug self-administration under various conditions, as well as state-of-the-art techniques that allow us to measure neurochemical and electrical changes in behaving subjects, administer pharmacological agents into specific brain targets, or specifically manipulate neuronal pathways using targeted viral vectors infections. Our findings will enhance our knowledge of the neuronal systems that are involved in the way motivated behaviours are guided by rewards and environmental challenges. Consequently, this work will contribute to the understanding of the mechanisms underlying human behaviour.