LIP External Colloquium: Dave Clewett, University of California, Los Angeles, USA - "Neuromodulatory signals shape the organization of episodic memory"

Dave Clewett, University of California, Los Angeles, USA will present:
"Neuromodulatory signals shape the organization of episodic memory"

Abstract: Our lives unfold continuously, yet we remember the past as a series of distinct events. What determines where one event ends and another begins in memory? In this talk, I will present evidence that fluctuations in arousal-related neuromodulation, including the locus coeruleus-norepinephrine (LC-NE) and dopamine systems, play a key role in structuring episodic memory. Using an encoding paradigm combined with high-resolution fMRI, eye tracking, and neuromelanin MRI, we show that moments of change in experience trigger bursts of pupil-linked arousal and LC activation that help separate adjacent memories and reshape hippocampal event representations. We further show that contextual shifts expand the remembered time between events, and that these distortions relate to increases in ventral tegmental area (VTA) activation and blinking, two markers of dopaminergic processing. Together, these findings suggest that neuromodulatory systems help structure the temporal organization of memory by signaling meaningful changes in experience. I will conclude by discussing ongoing work testing whether disruptions in these arousal mechanisms contribute to fragmented or disorganized memories in post-traumatic stress disorder and Alzheimer’s disease.