Activity memory in traumatic brain injury: The role of encoding and retrieval

Under incidental learning conditions, traumatic brain injury (TBI) survivors exhibit worse recall and recognition for completed activities relative to healthy participants, but both groups demonstrate equivalent temporal order memory (TOM) for performed activities. We evaluated the role of encoding, consolidation, and retrieval in the activity memory (AM) in TBI.

25 TBI survivors and 24 healthy participants were compared. A battery of neuropsychological tests served as the "activities." Activity ratings were completed after each test, to promote incidental learning. Following the last rating, AM trials were administered. Encoding, consolidation, and retrieval were assessed via Item Specific Deficit Approach.

Age correcting ANCOVAs revealed worse AM recall in TBI participants, but equivalent TOM for activities. Hierarchical regressions showed that encoding predicted AM recall, but both encoding and retrieval predicted TOM for activities in the TBI group.

TBI-related memory deficits for AM recall are related to encoding, like observations of verbal memory deficits in TBI. TOM performances were predicted by both encoding and retrieval, suggesting that temporal order for activities, may be partially encoded by nondeclarative memory processes. This finding is partially consistent with previous work, showing that enhancing encoding improves recall for activities, but not TOM for activities.