Auditory Working Memory in Individuals with Traumatic Brain Injury

Abstract

Thirteen adult survivors of traumatic brain injury (TBI) and 10 healthy controls completed three working memory (WM) tasks: an auditory verbal n-back task, a listening span task, and a digit span task. The n-back task required that participants manually respond to previously specified types of matches located within strings of letters. In the listening span task, participants listened to sets of sentences during which they made true/false judgments, while at the same time maintaining the final word from each sentence in their working memory. The digit span task involved the recall of increasingly longer strings of numbers in either forward or backward order. Analysis of variance (ANOVA) was used when there were both between- and within-group comparisons, whereas simple group comparisons were made in the absence of within-group variables. In all tasks, participants demonstrated lower working memory scores as the tasks increased in length or difficulty. Participants with TBI made more errors on the listening span task, but did not perform worse on the n-back or digit span tasks compared to controls. Strong correlations were obtained between the n-back task scores and digit span backward scores within the TBI group whereas a moderate correlation was determined between the listening span task and digit span backward. Strong correlations were also found between predicted verbal IQ scores, verbal fluency scores, and errors on the listening span task, suggesting that pre-injury vocabulary and post-injury word retrieval are related to this WM task, which involves language. The clinical significance of these results is discussed.