Director's Seminar Series - Professor Pankaj Sah, The University of Queensland

Fear learning and extinction: Neural circuits and engrams

Host: Prof. John Bekkers

Abstract

Fear conditioning is a simple Pavlovian learning paradigm during which a sensory stimulus, the conditioned stimulus (CS), such as a tone is contingently paired with aversive stimulus. This pairing leads to an association such that the sensory stimulus is predictive of an aversive event. This association is stored as a memory in a network of neurons called the engram. On encountering the CS at a later time the memory is recalled, and the subject responds with defensive responses, a protective behaviour. This memory is long lasting. However, repeated presentations of the CS alone uncouples the two events and subjects learn that the CS is no longer dangerous, forming a new memory. I will discuss circuit mechanisms that underpin fear learning and its extinction, and describe experiments to understand the nature of the memory engram.

Biography

Professor Pankaj Sah is Director of the Queensland Brain Institute at The University of Queensland. He is renowned for his work in understanding the neural circuitry of the amygdala, an area of the brain that plays a central role in learning and memory formation. Dysfunction of the amygdala leads to a host of anxiety-related disorders. His laboratory uses a combination of molecular tools, electrophysiology, anatomical reconstruction, calcium imaging and behavioural studies to examine the electrophysiological signatures of different brain regions and their impact on disease. More recently his lab has been working with patients undergoing electrode implantation for deep brain stimulation, used to treat disorders such as Parkinson's disease, Tourette's, OCD and essential tremor. He is also the Editor-in-Chief of the Nature Partner Journal npj Science of Learning.