Verbal memory impairment in severe closed head injury: The role of encoding and consolidation

Abstract

We applied the item-specific deficit approach (ISDA) to California Verbal Learning Test data obtained from 56 severe, acceleration–deceleration closed head injury (CHI) participants and 62 controls. The CHI group demonstrated deficits on all ISDA indices in comparison to controls. Regression analyses indicated that encoding deficits, followed by consolidation deficits, accounted for most of the variance in delayed recall. Additionally, level of acquisition played a partial role in CHI-associated consolidation difficulties. Finally, CHI encoding deficits were largely driven by low semantic clustering during list learning. These results suggest that encoding (primary) and consolidation (secondary) deficits account for CHI-associated verbal memory impairment.

Keywords:

• Traumatic brain injury
• Memory
• Neuropsychology
• Encoding
• Consolidation

Special thanks to Anna Curren for her assistance in data collection and coding. This research was supported in part by a Marchionne Memorial Doctoral Fellowship awarded by Washington State University, an American Psychological Association Dissertation Research Award, a Van Vleet Memorial Doctoral Fellowship, a Vidulich Research Fellowship awarded by The University of Memphis, National Institute of Child Health and Human Development (NICHD) Grant HD35838, National Institute of Neurological Disorders and Stroke (NINDS) Grant NS47690, and National Institute of Mental Health (NIMH) Grant MH19535.