title: Pivotal role of anterior cingulate cortex in working memory after traumatic brain injury in youth.
abstract: In this fMRI study, the functions of the anterior cingulate cortex (ACC) were studied in a group of adolescents who had sustained a moderate to severe traumatic brain injury (TBI). A spatial working memory task with varying working memory loads, representing experimental conditions of increasing difficulty, was administered. In a cross-sectional comparison between the patients and a matched control group, patients performed worse than Controls, showing longer reaction times and lower response accuracy on the spatial working memory task. Brain imaging findings suggest a possible double-dissociation: activity of the ACC in the TBI group, but not in the Control group, was associated with task difficulty; conversely, activity of the left sensorimotor cortex (lSMC) in the Control group, but not in the TBI group, was correlated with task difficulty. In addition to the main cross-sectional study, a longitudinal study of a group of adolescent patients with moderate to severe TBI was done using fMRI and the same spatial working memory task. The patient group was studied at two time-points: one time-point during the post-acute phase and one time-point 12 months later, during the chronic phase. Results indicated that patients' behavioral performance improved over time, suggesting cognitive recovery. Brain imaging findings suggest that, over this 12-month period, patients recruited less of the ACC and more of the lSMC in response to increasing task difficulty. The role of ACC in executive functions following a moderate to severe brain injury in adolescence is discussed within the context of conflicting models of the ACC functions in the existing literature.
authors.affiliation: Psychiatry and Biobehavioral Sciences, University of California Los Angeles David Geffen School of Medicine Los Angeles, CA, USA.
authors.forename: Fabienne
authors.initials: F
authors.lastname: Cazalis
authors.forename: Talin
authors.initials: T
authors.lastname: Babikian
authors.forename: Christopher
authors.initials: C
authors.lastname: Giza
authors.forename: Sarah
authors.initials: S
authors.lastname: Copeland
authors.forename: David
authors.initials: D
authors.lastname: Hovda
authors.forename: Robert F
authors.initials: RF
authors.lastname: Asarnow