General semantic, personal semantic and episodic details when thinking about the past and the future in moderate-to-severe traumatic brain injury

Relational memory supports the binding of the arbitrary relations between elements of experience to create durable representations of our lives over time, an ability that is disrupted following traumatic brain injury (TBI). Much of the work on relational memory in TBI comes from studies on the recall of specific events from one's personal past, that is, episodic memory. Recent work suggests relational memory may also be recruited in support of representations of general semantics (i.e., knowledge of the world) and personal semantics (i.e., knowledge about the self and one's life). In the present study, we assessed whether the repercussions of TBI on relational memory extend beyond episodic memory to include aspects of general and personal semantics using similar tasks focused on elaboration. Thirty individuals with moderate-severe TBI and 30 non-injured participants (NCs) generated narratives across four life chapters (adolescence, remote past, recent past, future) and three memory types (general semantics, personal semantics, and episodic memory). A mixed effects model revealed a significant effect of Group, without any interaction, consistent with the TBI group having generated fewer details than the NC group across all chapters and memory types. The provision of specific probes reduced the differences between groups, except for the autobiographical facts of the future chapter. The study assessed a uniquely large spectrum of memory types and showed that relational memory dysfunction in TBI extends beyond episodic memory to include aspects of general and personal semantics, for both the past and future.