Brain imaging correlates of verbal working memory in children following traumatic brain injury

Abstract

Neural correlates of working memory (WM) based on the Sternberg Item Recognition Task (SIRT) were assessed in 40 children with moderate-to-severe traumatic brain injury (TBI) compared to 41 demographically-comparable children with orthopedic injury (OI). Multiple magnetic resonance imaging (MRI) methods assessed structural and functional brain correlates of WM, including volumetric and cortical thickness measures on all children; functional MRI (fMRI) and diffusion tensor imaging (DTI) were performed on a subset of children. Confirming previous findings, children with TBI had decreased cortical thickness and volume as compared to the OI group. Although the findings did not confirm the predicted relation of decreased frontal lobe cortical thickness and volume to SIRT performance, left parietal volume was negatively related to reaction time (RT). In contrast, cortical thickness was positively related to SIRT accuracy and RT in the OI group, particularly in aspects of the frontal and parietal lobes, but these relationships were less robust in the TBI group. We attribute these findings to disrupted fronto-parietal functioning in attention and WM. fMRI results from a subsample demonstrated fronto-temporal activation in the OI group, and parietal activation in the TBI group, and DTI findings reflected multiple differences in white matter tracts that engage fronto-parietal networks. Diminished white matter integrity of the frontal lobes and cingulum bundle as measured by DTI was associated with longer RT on the SIRT. Across modalities, the cingulate emerged as a common structure related to performance after TBI. These results are discussed in terms of how different imaging modalities tap different types of pathologic correlates of brain injury and their relationship with WM.

A Decade of DTI in Traumatic Brain Injury: 10 Years and 100 Articles Later

“…The average number of patients per study was 23 (range, 5-83 subjects). Our review identified several articles that described patient samples with extremely similar or identical demographic characteristics (eg, McCauley et al 55 and Wilde et al, 87,88,90 ) but reported either different abnormal brain regions or different analyses of DTI in relation to outcome. Thus, some of the subjects may have been reported in multiple studies published by the same group of researchers.…”

“…In 3 pediatric studies, the control groups were children who were hospitalized for orthopedic injury but had no evidence of head injury. 43,55,90 The average number of control subjects per study was 18 (range, 6 -47). Several articles, in addition to comparing patients with TBI with controls by using DTI, looked at subgroups of patients with TBI, including patients with TBI with major depressive disorders, 53,99 with raised intracranial pressures, 81 with spinal cord injuries, 86 or veterans with blast injuries.…”

Early Cortical Thickness Change after Mild Traumatic Brain Injury following Motor Vehicle Collision

“…Precuneus is involved in episodic memory retrieval, 54 and the cortical thickness of a region in the right precuneus was positively correlated with the response time and errors of a working memory task in children without TBI. 24 Moderate to severe TBI altered these relationships in children as early as 4 days after head trauma. 24 Cortical thickness of a region including the left precuneus has been positively correlated with performance on a declarative memory task in adult survivors with severe TBI.…”

“…24 Moderate to severe TBI altered these relationships in children as early as 4 days after head trauma. 24 Cortical thickness of a region including the left precuneus has been positively correlated with performance on a declarative memory task in adult survivors with severe TBI. 22 This possible link to memory function remains interesting but speculative because we did not assess memory function.…”

“…Recent studies using this approach revealed progressive cortical thinning in moderate to severe TBI in children and adults. [22][23][24] To date, however, few studies have examined cortical thickness in mTBI survivors during the early post-mTBI period.…”