My research programme aims to understand the brain basis of complex human behavior, with a particular focus on frontal-executive functions and decision-making. I take a component process approach, identifying simpler building blocks of complex behaviours, and relating these simpler processes to their underlying neural substrates, primarily through behavioural studies of human subjects who have suffered focal brain injury.
This work has led me to focus on prefrontal cortex in general, and medial and orbitofrontal cortex in particular. Ventral and medial prefrontal cortex are poorly-understood regions of the brain which appear to play important roles in tracking the value of potential choices, and optimizing on-going performance, particularly in cognitively-demanding or rapidly changing contexts. These brain areas have also been implicated in social, emotional, and autonomic functions; work on the component processes of decision-making is relevant to an integrative understanding of the roles of these brain regions in these seemingly disparate aspects of behavior, something my lab is actively studying, again in human subjects with prefrontal damage.
This core basic research program sheds light on the neural systems important for decision-making, motivation, and self-control, all poorly-understood aspects of behaviour that are commonly disrupted in many neurological and psychiatric illnesses. Because this work is carried out in human subjects, it has particularly immediate translational potential. My lab works in several translational research areas, including stroke, multiple sclerosis, HIV, addiction and obesity.
Decision-making research is relevant to understanding a wide range of human behaviour, such as self-control, impulsivity, economic choice, and social interactions including bargaining, voting, and solving ethical dilemmas. The lab has collaborations at McGill in Psychology, Management, Kinesiology, and Political Science to pursue some of these directions.
Lesley Fellows, MD CM, DPhil
We make many decisions, large and small, every day, yet know very little about the brain processes that underlie these decisions. What brain mechanisms allow us to calculate the value of possible options, and to weigh that value against the costs (such as time and effort) of a particular course of action? This research will help to answer these questions, by examining how specific regions within the brain's frontal lobes are involved in the basic building blocks of decision making. This work is done with the help of patients who have suffered injury to specific parts of the frontal lobes, and so also provides a better understanding of why such patients have problems with motivation, judgment, and decision making in their everyday lives. In addition, this research has implications for understanding the brain basis of common psychiatric conditions that are characterized by poor decisions, such as drug addiction.
The brain basis of political choice
This inter-disciplinary research aims to understand the brain basis of political choice: such as decisions about policy, political leadership, voting. We ask whether the same brain systems important for economic choice are also engaged in the political context. In collaboration with Elisabeth Gidengil, Dietland Stolle, Centre for the Study of Democratic Citizenship, Dept. of Political Science, McGill
Executive functions are amongst the most complex processes supported by the brain. Often linked to the frontal lobes, these functions likely rely on extensive network interactions. This likely explains why these processes are so frequently affected by medical conditions that degrade brain function, such as in multiple sclerosis, Parkinson’s disease, or longstanding HIV infection. On-going research in these populations aims to improve how cognition and executive function is measured, and to deepen our understanding of the mechanisms that underlie impairments. Research in collaboration with Positive Brain Health Now: Understanding and improving brain health in HIV and The Brain Health Outcomes Platform (BHOP).
Action control and decision-making
When controlling the movement of our bodies, we make adjustments in response to errors, successes, and rewards. This research aims at understanding the brain mechanisms underlying our ability to guide and refine actions based on reward and error feedback. These questions are tested in patients with focal injury to specific parts of the frontal lobes and basal ganglia.