Philip Corlett - Delusions and the Brain: Learning about odd beliefs through Cognitive Neuroscience

This talk was given at the Athinoula A. Martinos Center for Biomedical Imaging in Charlestown, MA on June 26, 2013.
Philip Corlett, Ph.D.
Yale University
Delusions and the Brain: Learning about odd beliefs through Cognitive Neuroscience
I'll discuss the psychology and neurobiology of belief formation, how it can inform our understanding of one of the cardinal symptoms of mental illness; delusions; the bizarre and tenacious beliefs that attend serious mental illnesses like schizophrenia. By drawing on recent advances in the biological, computational and psychological processes of reinforcement learning, memory, and perception, I will argue that it may be feasible to account for delusions in terms of cognition and brain function. My explanation focuses on a particular parameter, prediction error--the mismatch between expectation and experience--that provides a computational mechanism common to many disparate brain systems. I'll suggest that delusions result from aberrations in how brain circuits specify hierarchical predictions, and how they compute and respond to prediction errors. Defects in these fundamental brain mechanisms can vitiate perception, memory, bodily agency and social learning such that individuals with delusions experience an internal and external world that healthy individuals would find difficult to comprehend. Finally, I'll describe recent work on the fixity of delusions; which may also be explained in terms of aberrant prediction error processing. Surprising events demand a change in our expectancies. This involves making what we have learned labile, updating and binding the memory anew: a process of memory reconsolidation. I will argue that, under the influence of excessive prediction error, delusional beliefs are repeatedly reconsolidated, strengthening them so that they persist, apparently impervious to contradiction.