Schedule of Events | Symposia

Hippocampal neural timescales during movie watching are related to gist memory and to age

Poster Session C - Sunday, March 30, 2025, 5:00 – 7:00 pm EDT, Back Bay Ballroom/Republic Ballroom

Nichole R. Bouffard¹, Angelique I. Delarazan¹, Jeffrey M. Zacks¹, Zachariah M. Reagh¹; ¹Washington University in Saint Louis

Older adults’ memories are more gist-like, with fewer fine-grained details, compared to those of younger adults’. It has been proposed that neural signal gradients in the hippocampus support coarse-to-fine representations in memory. However, it is unknown whether this neural gradient changes with age, and how it might relate to the shift towards gist-like memory. Here, we applied a new fMRI analytic technique that measured the neural timescale of single voxels in the hippocampus. We computed the temporal autocorrelation window–the area under the autocorrelation function curve–to measure length of the neural timescales in the hippocampus while younger and older adults watched a movie. After movie-watching, participants recalled the entire movie, and their recall was scored for gist and detail memory. We found that older adults had more gist-like recall compared to younger adults. In both younger and older adults, longer neural timescales in the hippocampus during movie watching were related to more gist-like recall of the movie. In line with prior studies, younger adults had a gradient of neural timescales from anterior-medial (longer) to posterior-lateral (shorter) hippocampus. However, this gradient was absent in older adults, suggesting a dedifferentiation of signals throughout the hippocampus. These findings reveal gradients in neural timescales to be a novel means of studying age-related differences in hippocampal function. Furthermore, these hippocampal timescales might underlie gist-biases in older adults’ memories.

Topic Area: LONG-TERM MEMORY: Episodic