This study aimed to delineate the cerebral attentional network in patients with traumatic brain injury (TBI) and assess for adaptations in this network in response to a rehabilitation intervention.
Seventeen patients with TBI and 15 healthy subjects underwent functional magnetic resonance imaging (fMRI) using a visuospatial attention task. Ten TBI patients who successfully completed attentional training had a follow-up fMRI.
In the TBI patients, fMRI analysis showed more activation in the frontal and temporoparietal lobes, as well as less activation in the anterior cingulated gyrus, SMA, and temporooccipital regions compared to the healthy subjects. Following cognitive training, the TBI patients improved performance of attention tasks accompanied by changes in attentional network activation; the activity of the frontal lobe decreased, whereas activation of the anterior cingulate cortices and precuneus increased.
These findings demonstrate the plasticity and training induced redistribution of the visuospatial attentional network in TBI patients.
"As an example, fMRI research has helped to identify neural mechanism associated with attentional training (Y. H. Kim et al., 2009). In this study, all participants completed a visuospatial attention task in conjunction with fMRI. "
[Show abstract][Hide abstract] ABSTRACT: Nearly 1.7 million Americans sustain a traumatic brain injury (TBI) each year. These injuries can result in physical, emotional, and cognitive consequences. While many individuals receive cognitive rehabilitation from occupational therapists (OTs), the interdisciplinary nature of TBI research makes it difficult to remain up-to-date on relevant findings. We conducted a literature review to identify and summarize interdisciplinary evidence-based practice targeting cognitive rehabilitation for civilian adults with TBI. Our review summarizes TBI background, and our cognitive remediation section focuses on the findings from 37 recent (since 2006) empirical articles directly related to cognitive rehabilitation for individuals (i.e., excluding special populations such as veterans or athletes). This manuscript is offered as a tool for OTs engaged in cognitive rehabilitation and as a means to highlight arenas where more empirical, interdisciplinary research is needed.
"According to this position, the transient involvement of additional neural resources is viewed as neither abnormal nor permanent, but rather necessary for task performance. Support for this comes from the finding that the most common site for neural recruitment, the dorsolateral prefrontal cortex, holds a relationship with task reaction time (Hillary et al., 2010) and task novelty and load (Hillary et al., 2011; Kim et al., 2009; Medaglia et al., 2012; Perlstein et al., 2004) in both TBI and matched HC subjects. Cognitive load manipulations frequently increase the complexity of the task or amount of information that an individual must hold in WM. "
[Show abstract][Hide abstract] ABSTRACT: Individuals with mild traumatic brain injury (TBI) often have deficits in processing speed and working memory (WM) and there is a growing literature using functional imaging studies to document these deficits. However, divergent results from these studies revealed both hypoactivation and hyperactivation of neural resources after injury. We hypothesized that at least part of this variance can be explained by distinct demands between WM tasks. Notably, in this literature some WM tasks use discrete periods of encoding, maintenance, and retrieval, whereas others place continuous demands on WM. The purpose of this meta-analysis is to examine the differences in neural recruitment after mTBI to determine if divergent findings can be explained as a function of task demand and cognitive load. A comprehensive literature review revealed 14 studies using functional magnetic resonance imaging to examine brain activity of individuals with mTBI during working memory tasks. Three of the fourteen studies included reported hypoactivity, five reported hyperactivity, and the remaining six reported both hypoactivity and hyperactivity. Studies were grouped according to task type and submitted to GingerALE maximum likelihood meta-analyses to determine the most consistent brain activation patterns. The primary findings from this meta-analysis suggest that the discrepancy in activation patterns is at least partially attributable to the classification of WM task, with hyperactivation being observed in continuous tasks and hypoactivation being observed during discrete tasks. We anticipate that differential task load expressed in continuous and discrete WM tasks contributes to these differences. Implications for the interpretation of fMRI signals in clinical samples are discussed. (JINS, 2013, 19, 1-12).
Journal of the International Neuropsychological Society 05/2013; 19(07):1-12. DOI:10.1017/S1355617713000490 · 2.96 Impact Factor
"An important factor for a TBI patient is the time since injury. While very few longitudinal TBI imaging studies have been reported, several groups have reported functional-or diffusion-related changes within TBI populations between initial and follow-up scan sessions , both with and without cognitive training in the interim (McAllister et al., 2006; Sanchez-Carrion et al., 2008a; Kim et al., 2009). Diffusion differences have also been noted between mild TBI subjects imaged less than 3 months post-injury and those imaged more than 3 months post-injury (Rutgers et al., 2008). "
[Show abstract][Hide abstract] ABSTRACT: This review focuses on the application of functional magnetic resonance imaging (fMRI) to the investigation of blast-related traumatic brain injury (bTBI). Relatively little is known about the exact mechanisms of neurophysiological injury and pathological and functional sequelae of bTBI. Furthermore, in mild bTBI, standard anatomical imaging techniques (MRI and computed tomography) generally fail to show focal lesions and most of the symptoms present as subjective clinical functional deficits. Therefore, an objective test of brain functionality has great potential to aid in patient diagnosis and provide a sensitive measurement to monitor disease progression and treatment. The goal of this review is to highlight the relevant body of blast-related TBI literature and present suggestions and considerations in the development of fMRI studies for the investigation of bTBI. The review begins with a summary of recent bTBI publications followed by discussions of various elements of blast-related injury. Brief reviews of some fMRI techniques that focus on mental processes commonly disrupted by bTBI, including working memory, selective attention, and emotional processing, are presented in addition to a short review of resting state fMRI. Potential strengths and weaknesses of these approaches as regards bTBI are discussed. Finally, this review presents considerations that must be made when designing fMRI studies for bTBI populations, given the heterogeneous nature of bTBI and its high rate of comorbidity with other physical and psychological injuries.
Frontiers in Neurology 03/2013; 4:16. DOI:10.3389/fneur.2013.00016
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