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Multimodal imaging of mild traumatic brain injury and persistent postconcussion syndrome.

Dean PJ, Sato JR, Vieira G, McNamara A, Sterr A - Brain Behav (2014)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: School of Psychology, University Of Surrey Guildford, UK.

ABSTRACT

Background: 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.

Aim: 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.

Methods: 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.

Results: 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.

Conclusion: 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.

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Related in: MedlinePlus

Illustration of (A) Study Design, (B) n-Back task and (C) PVSAT task. (A) illustrates the block design of the fMRI tasks (white numbers on black background) interspersed with rest screens (white cross on black background). Each block is preceded by an information screen telling the participant what type of block is coming next. At the end of the block, feedback (percent correct) is given, and the participant signals their wish to proceed to the next block by pressing any button. The example n-Back (B) is a 1-Back. First the number 6 appears, then 3 sec later the number 5, then 5 then 8. The task for 1-Back is to match the number currently presented to the number one previous. Five and 6 do not match, so the participant must respond using the nontarget button. However, 5 and 5 do match, so this requires a target button response. In the PVSAT example (C), the target number is 11 and the speed is 2s. First the number 6 appears, and then the number 5 appears 2 sec later, then 3, then 8. The task is to add the number on screen to the one previous: 5 + 6 = 11. This is the target number, so the participant must respond using the target button. Next, when the 3 appears, you must add it to the 5 (3 + 5 = 8). This is not the target number, so requires a nontarget button response.
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fig01: Illustration of (A) Study Design, (B) n-Back task and (C) PVSAT task. (A) illustrates the block design of the fMRI tasks (white numbers on black background) interspersed with rest screens (white cross on black background). Each block is preceded by an information screen telling the participant what type of block is coming next. At the end of the block, feedback (percent correct) is given, and the participant signals their wish to proceed to the next block by pressing any button. The example n-Back (B) is a 1-Back. First the number 6 appears, then 3 sec later the number 5, then 5 then 8. The task for 1-Back is to match the number currently presented to the number one previous. Five and 6 do not match, so the participant must respond using the nontarget button. However, 5 and 5 do match, so this requires a target button response. In the PVSAT example (C), the target number is 11 and the speed is 2s. First the number 6 appears, and then the number 5 appears 2 sec later, then 3, then 8. The task is to add the number on screen to the one previous: 5 + 6 = 11. This is the target number, so the participant must respond using the target button. Next, when the 3 appears, you must add it to the 5 (3 + 5 = 8). This is not the target number, so requires a nontarget button response.

Mentions: Participants were presented with the same two behavioral tasks used in the prior cognitive study (Dean and Sterr 2013): the n-Back and the Paced Visual Serial Addition Task (PVSAT). Both the n-Back and PVSAT had four conditions or levels of difficulty (n-Back: 0-Back, 1-Back, 2-Back, 3-Back; PVSAT: 2.5 sec PVSAT, 2 sec PVSAT, 1.5 sec PVSAT, 1 sec PVSAT). The paradigm for both tasks was a block design (Fig.1A), with 12 blocks containing three randomly ordered repetitions of the four levels of difficulty. Task-related blocks started with an information screen detailing the difficulty level of the upcoming block presented for 1–3 sec (jittered) and were alternated with 20s rest blocks (white crosshair in center of black screen, see Fig.1A). A feedback screen was presented after each block detailing participant's performance. The order of presentation (n-Back/PVSAT) was counterbalanced across participants.


Multimodal imaging of mild traumatic brain injury and persistent postconcussion syndrome.

Dean PJ, Sato JR, Vieira G, McNamara A, Sterr A - Brain Behav (2014)

Illustration of (A) Study Design, (B) n-Back task and (C) PVSAT task. (A) illustrates the block design of the fMRI tasks (white numbers on black background) interspersed with rest screens (white cross on black background). Each block is preceded by an information screen telling the participant what type of block is coming next. At the end of the block, feedback (percent correct) is given, and the participant signals their wish to proceed to the next block by pressing any button. The example n-Back (B) is a 1-Back. First the number 6 appears, then 3 sec later the number 5, then 5 then 8. The task for 1-Back is to match the number currently presented to the number one previous. Five and 6 do not match, so the participant must respond using the nontarget button. However, 5 and 5 do match, so this requires a target button response. In the PVSAT example (C), the target number is 11 and the speed is 2s. First the number 6 appears, and then the number 5 appears 2 sec later, then 3, then 8. The task is to add the number on screen to the one previous: 5 + 6 = 11. This is the target number, so the participant must respond using the target button. Next, when the 3 appears, you must add it to the 5 (3 + 5 = 8). This is not the target number, so requires a nontarget button response.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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fig01: Illustration of (A) Study Design, (B) n-Back task and (C) PVSAT task. (A) illustrates the block design of the fMRI tasks (white numbers on black background) interspersed with rest screens (white cross on black background). Each block is preceded by an information screen telling the participant what type of block is coming next. At the end of the block, feedback (percent correct) is given, and the participant signals their wish to proceed to the next block by pressing any button. The example n-Back (B) is a 1-Back. First the number 6 appears, then 3 sec later the number 5, then 5 then 8. The task for 1-Back is to match the number currently presented to the number one previous. Five and 6 do not match, so the participant must respond using the nontarget button. However, 5 and 5 do match, so this requires a target button response. In the PVSAT example (C), the target number is 11 and the speed is 2s. First the number 6 appears, and then the number 5 appears 2 sec later, then 3, then 8. The task is to add the number on screen to the one previous: 5 + 6 = 11. This is the target number, so the participant must respond using the target button. Next, when the 3 appears, you must add it to the 5 (3 + 5 = 8). This is not the target number, so requires a nontarget button response.
Mentions: Participants were presented with the same two behavioral tasks used in the prior cognitive study (Dean and Sterr 2013): the n-Back and the Paced Visual Serial Addition Task (PVSAT). Both the n-Back and PVSAT had four conditions or levels of difficulty (n-Back: 0-Back, 1-Back, 2-Back, 3-Back; PVSAT: 2.5 sec PVSAT, 2 sec PVSAT, 1.5 sec PVSAT, 1 sec PVSAT). The paradigm for both tasks was a block design (Fig.1A), with 12 blocks containing three randomly ordered repetitions of the four levels of difficulty. Task-related blocks started with an information screen detailing the difficulty level of the upcoming block presented for 1–3 sec (jittered) and were alternated with 20s rest blocks (white crosshair in center of black screen, see Fig.1A). A feedback screen was presented after each block detailing participant's performance. The order of presentation (n-Back/PVSAT) was counterbalanced across participants.

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: School of Psychology, University Of Surrey Guildford, UK.

ABSTRACT

Background: 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.

Aim: 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.

Methods: 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.

Results: 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.

Conclusion: 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.

Show MeSH
Related in: MedlinePlus