The relationship between mnemonic discrimination and relational memory impairments in Traumatic Brain Injury

Poster Session B - Sunday, April 14, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Michael Dulas¹ (mdulas@binghamton.edu), Hillary Schwarb², Emily Morrow³, Nirav Patel³, Neal Cohen⁴, Melissa Duff³; ¹Binghamton University, ²University of Nebraska, ³Vanderbilt University, ⁴University of Illinois

Memory complaints are common after Traumatic Brain Injury (TBI), with recent work suggesting such deficits may be greatest for relational memory. Relational memory, the ability to bind together and retrieve relational representations, is critically mediated by the hippocampus, suggesting that TBI may result in hippocampal dysfunction. However, the hippocampus also subserves mnemonic discrimination, the ability to distinguish between highly similar, but distinct information in memory. Currently, it is unknown whether TBI impairs both hippocampal functions and, if so, whether such deficits are related. In the present study, 50 individuals with moderate-severe TBI and 50 neurotypical comparison (NC) participants completed relational memory and mnemonic discrimination tasks. In the relational memory task, participants studied triplets of abstract items and were asked to remember a target piece of information about them: either item identity, spatial arrangement, temporal order, or group membership. In the Mnemonic Similarity Task (MST), participants studied a series of nameable objects and, at test, determined which objects were Old (exactly the same as study), New (unstudied), or Similar (similar to a studied object but unique). Relative to NC’s, individuals with TBI were impaired on all domains of relational memory, but only showed deficits on similarity discrimination on the MST, with intact item memory. Similarity discrimination was also significantly correlated with performance on all of the relational memory domains in TBI. Taken together, results show that relational memory and mnemonic discrimination are both impaired in TBI, and that such impairments may be tied to a shared underlying deficit in hippocampal function.

Topic Area: LONG-TERM MEMORY: Episodic