UCL Division of Biosciences


NPP Seminar - Associate Professor Mazen Kheirbek, UCSF University of California, San Francisco

14 December 2023, 1:00 pm–2:00 pm

Mazen Kheirbek

Title: 'Representing rewarding and aversive experiences in ventral hippocampal circuits'

This event is free.

Event Information

Open to







Charlette Bent-Gayle – UCL, Neuroscience, Physiology, Pharmacology


131 A V Hill LT
Medical Sciences and Anatomy, Medical Sciences
Gower Street
United Kingdom

Abstract: In this talk I will discuss our recent efforts to understand how meaningful stimuli are represented in hippocampal circuits. First, I will discuss experiments using two-photon calcium imaging to track the same dCA1 and vCA1 neurons across days to determine how responses evolve across phases of odor–outcome learning. We found that odors elicited robust responses in dCA1, whereas, in vCA1, odor responses primarily emerged after learning and embedded information about the paired outcome. Population activity in both regions rapidly reorganized with learning and then stabilized, storing learned odor representations for days, even after extinction or pairing with a different outcome. Then we examined how unconditioned stimuli are represented in the hippocampus. We demonstrate that ensembles of vCA1 neurons represent the identity, sensory features, and intensity of conditioned and unconditioned salient stimuli, but not their overall valence. Stimulus representations within a sensory modality are more similar to one another than across modalities, and within the taste modality, we find vCA1 groups together stimuli that recruit the same taste pathway. Finally, I will discuss recent work using high-density electrophysiology to investigate how ventral hippocampal-amygdala interactions may modulate reward seeking after chronic stress.  These results will show how the hippocampus encodes, stores and updates information and illuminates the unique contributions of the ventral hippocampus.

Academic Host: Andrew Macaskill

About the Speaker

Mazen Kheirbek

Associate Professor in the Department of Psychiatry and Behavioral Sciences, the Graduate Program in Neuroscience, Kavli Institute for Fundamental Neuroscience at UCSF at University of California

Mazen Kheirbek, PhD is an Associate Professor in the Department of Psychiatry and Behavioral Sciences, the Graduate Program in Neuroscience, Kavli Institute for Fundamental Neuroscience at UCSF. He performed his undergraduate work at Washington University in St. Louis, received his PhD in neurobiology from the University of Chicago and completed his postdoctoral work at Columbia University. Since 2016 he has led a systems neuroscience research group housed in the Center for Integrative Neuroscience at UCSF. His group uses behavioral analysis, optogenetic tools, anatomical tools, computational methods, electrophysiological and imaging techniques to identify circuits that generate emotional behavior. In recent years, his group and collaborators have made a number of important contributions including: discovering circuits by which the hippocampus modulates emotional behavior, a role for adult generated hippocampal neurons in behavior, the encoding properties of the hippocampal dentate gyrus and a role for white matter plasticity in recall of fear memories. Dr. Kheirbek’s group have won numerous awards for their work, including The Freedman Prize Honorable Mention from BBRF, the One Mind Institute Rising Star Award, an HFSP Young Investigator Award, a Pew Biomedical Scholar Award, a Klingenstein-Simons Fellowship and a McKnight Foundation Memory and Cognitive Disorders Award.

More about Mazen Kheirbek