Spatial relational memory in individuals with traumatic brain injury

Introduction: Relational memory is the ability to bind arbitrary relations between elements of experience into durable representations and the flexible expression of these representations. It is well known that individuals with traumatic brain injury (TBI) have declarative memory impairments, but less is known about how TBI affects relational memory binding, the deficit at the heart of declarative, or relational, memory impairment. The aim of the current study is to examine such deficits.Method: We used a spatial reconstruction task (SRT) with 29 individuals with TBI and 23 normal comparison (NC) participants to investigate four different types of spatial relations: (A) identity-location relations, i.e., the relationship between a specific item and its known location; (B) item-item relations, or the relationship between one item and another; (C) item-display relations, or the relationship between an item and its position in the display; and (D) compound-item relations, i.e., relations that involve combinations of A, B, and C.Results: Our data revealed that individuals with TBI showed impairments in learning identity-location relations and increased compound errors compared to NCs. We also found evidence that when item identity is disregarded, individuals with TBI do not perform differently from NCs. An exploratory analysis revealed that while relational memory performance was significantly correlated with scores on the California Verbal Learning Test (CVLT), more participants with TBI exhibited impairment on the SRT than of the CVLT.Conclusions: Our findings show that relational memory is impaired following TBI, and provide preliminary evidence for an easy-to-administer task with increased sensitivity to memory impairment.