Neural correlates of visual memory in patients with diffuse axonal injury

ABSTRACT

Primary objective: To investigate the neural substrates of visual memory in a sample of patients with traumatic brain injury (TBI). We hypothesized that patients with decreased grey and white matter volume in frontal and parietal cortices as well as medial temporal and occipital lobes would perform poorly on the tests of visual memory analysed.

Methods and procedures: 39 patients and 53 controls were assessed on tests of visual memory and learning from the Cambridge Neuropsychological Test Automated Battery (CANTAB). Patients with TBI were scanned with magnetic resonance imaging (MRI). Partial correlations and multiple regression analyses were used to examine relationships between cognitive variables and MRI volumetric findings. This study complements and extends previous studies by performing volumetric comparisons on a variety of resolution levels, from whole brain to voxel-based level analysis.

Main outcomes and results: Patients with TBI performed significantly worse than controls in all the tasks assessed. Performance was associated with wide-spread reductions in grey and white matter volume of several cortical and subcortical structures as well as with cerebrospinal fluid space enlargement in accordance with previous studies of memory in patients with TBI and cognitive models suggesting that memory problems involve the alteration of multiple systems.

Conclusions: Our results propose that compromised visual memory in patients with TBI is related to a distributed pattern of volume loss in regions mediating memory and attentional processing.

KEYWORDS:

• Traumatic brain injury
• visual memory
• magnetic resonance imaging

Declaration of Interest

This study involved secondary analysis of data collected by other studies, including the MRC collaborative Grant and TBICare. L.M.L. was funded by the Division of Anaesthesia, University of Cambridge. A.M. is supported by CLAHRC-East of England awards. E.L.C., J.G.O., J.P.C. and D.K.M. are funded by the Neuroscience Theme of the NIHR Cambridge Biomedical Research Centre and NIHR and by Framework Program 7 funding from the European Commission (CENTER-TBI). B.J.S. consults for Cambridge Cognition, Otsuka, Servier and Lundbeck. She holds a grant from Janssen/J&J and has share options in Cambridge Cognition. D.K.M also received lecture and consultancy fees and support for research from Glaxo SmithKline, Solvay and Linde. E.A.S. is funded by the Stephen Erskine Fellowship, Queens’ College, Cambridge, UK. V.F.J.N. is supported by a Health Foundation/Academy of Medical Sciences Clinician Scientist Fellowship.