Schedule of Events | Symposia

On a roll: Subjective recollection primes the brain to successfully retrieve unrelated memories via dopaminergic mechanisms

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

Matthew Dougherty¹ (matthew.dougherty@mail.utoronto.ca), Anuya Patil¹, Katherine Duncan¹; ¹University of Toronto

Which brain states prepare us to successfully retrieve memories? Animal models suggest that slowly changing concentrations of neuromodulators- specifically acetylcholine, dopamine, and norepinephrine- may shape retrieval. Inline with this possibility, our group previously found that novelty–a form of stimulus salience associated with neuromodulator release–decreased associative retrieval ability for multiple seconds (Patil & Duncan, 2018). Here, we test whether these novelty-evoked neuromodulators drove this finding by evaluating their relationship to neural reinstatement of memories. We used functional magnetic resonance imaging (fMRI, n=29) to test whether novelty-evoked neuromodulatory nuclei activity mediates neural reinstatement, indexed with encoding-retrieval similarity (ERS). Inline with previous research, participants recalled fewer places and faces associated with words when novel objects preceded these words (b=-0.2864, p<0.001). Compared to novel objects, preceding familiar objects also boosted ERS in regions throughout the ventral stream (all p<0.05). While the task only required participants to reinstate stimulus categories, preceding familiar objects specifically boosted trial-specific content reinstatement in the ventral stream. Contrary to expectations from prior literature, neuromodulatory centers did not signal novelty in this task. Surprisingly, we found that dopaminergic and cholinergic nuclei responded more to familiarity. The response in dopaminergic regions significantly predicted subsequent ERS in the lateral prefrontal cortex (b=0.007, p<0.01) and mediated the effect of preceding familiarity on subsequent ERS in the medial temporal lobe cortex (indirect effect (ab)=0.0004, p<0.05). Our findings point to dopamine’s lingering influence over retrieval, expanding the landscape of mechanisms that prepare us to remember.

Topic Area: LONG-TERM MEMORY: Episodic