Positive Experience Shifts Fear Memories Away from Basolateral Amygdala
Dr Melissa Sharpe
Tuesday, 08 July 2025, 1pm to 2pm
Sherrington Library, Sherrington Building Parks Road, Oxford OX1 3PT
Hosted by Professor Mark Walton
ABSTRACT:
The basolateral amygdala (BLA) is at the centre of all biological models that detail how we form fear memories across species. However, we have recently shown that GABAergic neurons in the lateral hypothalamus (LH GABA) become critical for formation of fear memories if subjects have recently had a positive experience. In this talk, I will present data on how the recruitment of LH GABA neurons to encode fear memories impacts the role of the BLA in encoding fear memories. Using both optogenetic and lesion manipulations of BLA activity, we first replicated findings that BLA activity is required for formation of fear memories in experimentally-naïve rats. However, we found that if rats have recently had a distinct, positively-valenced experience, the BLA was no longer necessary for the formation of the fear memory. This shows that recruitment of LH GABA neurons to encode fear memories shifts the encoding of fear memories away from the BLA. As one of the most replicable findings in the behavioural neuroscience literature is that BLA inactivation or damage produces deficits in the formation of fear memories, these data require a reconsideration of biological models of fear memories. More generally, this work shows that brain regions can be recruited to encode information outside their traditional specialization and suggest a more fluid approach to conceptualizing memory formation, which considers diversity of experience.
ABOUT THE SPEAKER:
Professor Melissa Sharpe is an Associate Professor of Psychology at the University of Sydney whose research investigates how the brain learns, predicts outcomes, and makes decisions. She focuses on the neural circuits underlying motivation and reinforcement learning, using techniques such as optogenetics, chemogenetics, and in vivo calcium imaging in rodent models.
She previously held a faculty position at UCLA and completed postdoctoral training at Princeton and the U.S. National Institute on Drug Abuse. Her work has been recognised with several honours, including the NSF CAREER Award.