An important function of the brain is to supply the body energy to meet its metabolic demand. This critical responsibility ultimately gives rise to what we know as feelings of hunger and satiety. In a world where food is becoming more available our appetite no longer simply reflects our nutritional needs but has become associated with a number of psychological factors that strongly affect our desire to eat. Understanding how brain regions that regulate such processes are functional connected will shed light on how different psychological factors can affect our eating habits. On these lines, the lab is currently engaged in two avenues of research both focusing on the functional connectivity of brain circuits that regulate appetite.
The neural circuits linking appetite, arousal, and emotion
In this project we aim to understand how the neural circuits that control appetite and arousal (hypothalamus) interact with brain regions that are important for encoding emotional memories (amygdala). Disruptions of the hypothalamus can result in severe abnormalities in an animal’s feeding behaviour, such that some animals under-eat and become leaner, while others over-eat, become lethargic and eventually becoming obese. The amygdala is a structure that highlights the emotional significance of events by modulating activity in other brain regions. Interestingly, the hypothalamus and amygdala are reciprocally connected indicating that emotions may influence eating via direct connections between these regions. Using advanced genetic tools, such as optogenetics and designer drug systems in transgenic moue and rat lines, coupled with whole-cell recordings in vitro and behaviorally in vivo we aim to gain insight in the link between appetite and emotions by studying the functional connections between the amygdala and hypothalamus.
The cholinergic control of appetite
Using similar techniques the lab has recently begun investigating how endogenous acetylcholine regulates appetite. Nicotine, the major biologically active tobacco ingredient, is a highly addictive substance that is known to suppress feeding behaviour. The rewarding nature of nicotine can act as a potent driver of impulsive “chain smoking” behaviour often enough replacing the rewarding aspects of food. A significant body of evidence indicates that the anorectic affects of nicotine are exerted directly at the level of hypothalamus and possibly via interactions with reward systems such as the stratum. Despite this, the role of endogenous cholinergic circuits in controlling food intake has received relatively little attention. We are currently mapping out the cholinergic projections to the hypothalamus and looking at their synaptic impact on both specific hypothalamic and striatal circuits in vitro and behaviourally on appetite. Part of this work is the focus of an ongoing collaboration with the Department of Psychology.