Poster Session A, Saturday, March 23, 1:30 pm - 3:30 pm, Pacific Concourse
Arousal Modulates the Temporal Structure of Episodic Memory
David Clewett1, Camille Gasser2, Lila Davachi2,3; 1New York University, 2Columbia University, 3Nathan Kline Institute
Although everyday life unfolds continuously, we tend to remember our experiences as being more discrete and episodic. But what creates an ‘episode’ in episodic memory? Research suggests that a stable context supports the ongoing integration of sequential information, compressing experience into memories of tight-knit events. By contrast, when the current context changes, a theoretical ‘event boundary’ disrupts sequential integration, instead separating experiences into more distinct memory representations. Although increasing evidence shows that boundaries influence episodic memory organization, little is known about the brain mechanisms that support these processes. Across three studies (N = 34; N = 35; N = 30), we found that event boundaries expanded estimates of temporal distance between item pairs, impaired order memory for recent item pairs, and enhanced item-source memory binding. Using eye tracking, we also found that boundaries elicited significantly greater pupil dilation, an index of physiological arousal, than other novel item presentations. A principle component analysis revealed distinct temporal profiles of this pupil response that were modulated by boundaries. Moreover, distinct pupil components also predicted different effects of boundaries on temporal memory, with parasympathetic inhibition being related to greater time dilation effects in memory and sympathetic activation being related to greater impairments in temporal order memory. In a fourth experiment, we are combining high-resolution fMRI of the medial temporal lobe/brainstem with eye tracking to see how neural memory representations are modulated by arousal at event boundaries. Taken together, these findings shed new light on how arousal mechanisms modulate memories of time and everyday events.
Topic Area: LONG-TERM MEMORY: Episodic