Functional abnormalities in normally appearing athletes following mild traumatic brain injury: A functional MRI study

Department of Kinesiology, The Pennsylvania State University, 19 Recreation Building, University Park, PA 16802, USA.
Experimental Brain Research (Impact Factor: 2.04). 04/2010; 202(2):341-54. DOI: 10.1007/s00221-009-2141-6
Source: PubMed

ABSTRACT Memory problems are one of the most common symptoms of sport-related mild traumatic brain injury (MTBI), known as concussion. Surprisingly, little research has examined spatial memory in concussed athletes given its importance in athletic environments. Here, we combine functional magnetic resonance imaging (fMRI) with a virtual reality (VR) paradigm designed to investigate the possibility of residual functional deficits in recently concussed but asymptomatic individuals. Specifically, we report performance of spatial memory navigation tasks in a VR environment and fMRI data in 15 athletes suffering from MTBI and 15 neurologically normal, athletically active age matched controls. No differences in performance were observed between these two groups of subjects in terms of success rate (94 and 92%) and time to complete the spatial memory navigation tasks (mean = 19.5 and 19.7 s). Whole brain analysis revealed that similar brain activation patterns were observed during both encoding and retrieval among the groups. However, concussed athletes showed larger cortical networks with additional increases in activity outside of the shared region of interest (ROI) during encoding. Quantitative analysis of blood oxygen level dependent (BOLD) signal revealed that concussed individuals had a significantly larger cluster size during encoding at parietal cortex, right dorsolateral prefrontal cortex, and right hippocampus. In addition, there was a significantly larger BOLD signal percent change at the right hippocampus. Neither cluster size nor BOLD signal percent change at shared ROIs was different between groups during retrieval. These major findings are discussed with respect to current hypotheses regarding the neural mechanism responsible for alteration of brain functions in a clinical setting.

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Available from: William J Ray, Sep 28, 2015
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    • "Similar results have been described using the same technique while examining the link between concussion and depression [43] and post-concussive syndrome [44]. fMRI studies following concussion in the acute stage (24 hours to one week) reveal alterations in neural activity in several different regions of the brain; including the frontal cortex [45], parietal cortex [46], and cerebellum [47]. Despite these studies being performed in the acute stages following a concussion, many of the participants showed no abnormalities on traditional neuropsychological and neurocognitive tests. "
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    ABSTRACT: Traumatic brain injury (TBI) is a complex pathophysiological process resulting from external forces applied to the skull and affecting the brain. TBI is a significant global contributor to disability and death, particularly in children and young adults. The severity of a TBI may range from " mild " (a brief change in mental status or consciousness) to " severe " (an extended period of unconsciousness or amnesia after the injury), with mild TBI (mTBI) the most common form, diagnosed in 80-90% of cases. Sports-related concussion contributes significantly to mTBI accounting for nearly 20% of all mTBI cases. In the past decade there has been increasing growing public concern regarding the association of sports concussion; in particular further chance of recurrent injury following a concussion due to transient cognitive impairments, and long-term detrimental mental health issues and deterioration in brain function as a consequence of multiple concussions. Attention is also turning to methods to assess concussion with questions surrounding the reliability in traditional methods of concussion assessment that include symptom observation and cognitive assessment. This chapter will discuss the neuroscience of sports-related concussion, reviewing the evidence from new and rigorous methods of concussion assessment, such as neuroimaging and electrophysiology, with a focus on transcranial magnetic stimulation, following acute concussive events through to long-term manifestations of multiple concussions.
    Horizons in Neuroscience Vol 20, Edited by Andres Costa and Eugenio Villalba, 03/2015; Nova.
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    • "However , there have been relatively few fMRI studies with a specific focus on mTBI, and the majority of these look at the subacute or acute phase post-injury (McDonald et al. 2012). Most of the studies have used working memory [in particular n-Back (McAllister et al. 1999, 2001; Smits et al. 2009; Pardini et al. 2010; Chen et al. 2012)] and attention-related (Smits et al. 2009; Witt et al. 2010; Terry et al. 2012) tasks and found alterations in activation in the frontal lobe [particularly in left middle frontal gyrus (MFG) or dorsolateral prefrontal cortex (DLPFC)] as well as activation of more widespread task-unrelated areas (McAllister et al. 2001; Slobounov et al. 2010; Witt et al. 2010; Chen et al. 2012). Other studies have shown alterations in neural areas related to the default mode network (DMN) (Johnson et al. 2012; Mayer et al. 2012) and the medial temporal lobe (Stulemeijer et al. 2010), possibly related to impaired task-related deactivation. "
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    ABSTRACT: Persistent postconcussion syndrome (PCS) occurs in around 5-10% of individuals after mild traumatic brain injury (mTBI), but research into the underlying biology of these ongoing symptoms is limited and inconsistent. One reason for this could be the heterogeneity inherent to mTBI, with individualized injury mechanisms and psychological factors. A multimodal imaging study may be able to characterize the injury better. To look at the relationship between functional (fMRI), structural (diffusion tensor imaging), and metabolic (magnetic resonance spectroscopy) data in the same participants in the long term (>1 year) after injury. It was hypothesized that only those mTBI participants with persistent PCS would show functional changes, and that these changes would be related to reduced structural integrity and altered metabolite concentrations. Functional changes associated with persistent PCS after mTBI (>1 year postinjury) were investigated in participants with and without PCS (both n = 8) and non-head injured participants (n = 9) during performance of working memory and attention/processing speed tasks. Correlation analyses were performed to look at the relationship between the functional data and structural and metabolic alterations in the same participants. There were no behavioral differences between the groups, but participants with greater PCS symptoms exhibited greater activation in attention-related areas (anterior cingulate), along with reduced activation in temporal, default mode network, and working memory areas (left prefrontal) as cognitive load was increased from the easiest to the most difficult task. Functional changes in these areas correlated with reduced structural integrity in corpus callosum and anterior white matter, and reduced creatine concentration in right dorsolateral prefrontal cortex. These data suggest that the top-down attentional regulation and deactivation of task-irrelevant areas may be compensating for the reduction in working memory capacity and variation in white matter transmission caused by the structural and metabolic changes after injury. This may in turn be contributing to secondary PCS symptoms such as fatigue and headache. Further research is required using multimodal data to investigate the mechanisms of injury after mTBI, but also to aid individualized diagnosis and prognosis.
    Brain and Behavior 02/2015; 5(1):45-61. DOI:10.1002/brb3.292 · 2.24 Impact Factor
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    • "One exception to this was the right inferior frontal gyrus that showed decreased activation in acutely injured athletes relative to controls in all phases of the task. It is noteworthy that this region has shown increased activation in injured athletes during the subacute period in response to working memory measures (Lovell et al., 2007; Pardini et al., 2010; Slobounov et al., 2010). A limitation of this study is the relatively small number of concussed and healthy participants. "
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    ABSTRACT: To study the natural recovery from sports concussion, 12 concussed high school football athletes and 12 matched uninjured teammates were evaluated with symptom rating scales, tests of postural balance and cognition, and an event-related fMRI study during performance of a load-dependent working memory task at 13 h and 7 weeks following injury. Injured athletes showed the expected postconcussive symptoms and cognitive decline with decreased reaction time (RT) and increased RT variability on a working memory task during the acute period and an apparent full recovery 7 weeks later. Brain activation patterns showed decreased activation of right hemisphere attentional networks in injured athletes relative to controls during the acute period with a reversed pattern of activation (injured > controls) in the same networks at 7 weeks following injury. These changes coincided with a decrease in self-reported postconcussive symptoms and improved cognitive test performance in the injured athletes. Results from this exploratory study suggest that decreased activation of right hemisphere attentional networks mediate the cognitive changes and postconcussion symptoms observed during the acute period following concussion. Conversely, improvement in cognitive functioning and postconcussive symptoms during the subacute period may be mediated by compensatory increases in activation of this same attentional network. (JINS, 2013, 19, 1-10).
    Journal of the International Neuropsychological Society 07/2013; 19(08):1-10. DOI:10.1017/S1355617713000702 · 2.96 Impact Factor
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