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Colour or shape: examination of neural processes underlying mental flexibility in posttraumatic stress disorder.

Pang EW, Sedge P, Grodecki R, Robertson A, MacDonald MJ, Jetly R, Shek PN, Taylor MJ - Transl Psychiatry (2014)

Bottom Line: MEG data were recorded and source localized to identify significant brain regions involved in the task.Activation latencies were obtained by analysing the time course of activation in each region.The control group showed a sequence of activity that involved dorsolateral frontal cortex, insula and posterior parietal cortices.

View Article: PubMed Central - PubMed

Affiliation: 1] Division of Neurology, Hospital for Sick Children, Toronto, ON, Canada [2] Neurosciences and Mental Health, SickKids Research Institute, Toronto, ON, Canada [3] Department of Paediatrics, University of Toronto, Toronto, ON, Canada.

ABSTRACT
Posttraumatic stress disorder (PTSD) is a mental disorder that stems from exposure to one or more traumatic events. While PTSD is thought to result from a dysregulation of emotional neurocircuitry, neurocognitive difficulties are frequently reported. Mental flexibility is a core executive function that involves the ability to shift and adapt to new information. It is essential for appropriate social-cognitive behaviours. Magnetoencephalography (MEG), a neuroimaging modality with high spatial and temporal resolution, has been used to track the progression of brain activation during tasks of mental flexibility called set-shifting. We hypothesized that the sensitivity of MEG would be able to capture the abnormal neurocircuitry implicated in PTSD and this would negatively impact brain regions involved in set-shifting. Twenty-two soldiers with PTSD and 24 matched control soldiers completed a colour-shape set-shifting task. MEG data were recorded and source localized to identify significant brain regions involved in the task. Activation latencies were obtained by analysing the time course of activation in each region. The control group showed a sequence of activity that involved dorsolateral frontal cortex, insula and posterior parietal cortices. The soldiers with PTSD showed these activations but they were interrupted by activations in paralimbic regions. This is consistent with models of PTSD that suggest dysfunctional neurocircuitry is driven by hyper-reactive limbic areas that are not appropriately modulated by prefrontal cortical control regions. This is the first study identifying the timing and location of atypical neural responses in PTSD with set-shifting and supports the model that hyperactive limbic structures negatively impact cognitive function.

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Related in: MedlinePlus

Reconstructed time courses from the right insula and left supramarginal gyrus to test the hypothesis of whether the insula is specifically recruited in unaffected individuals to maintain task performance. As the supramarginal gyrus does not show significant differences between PTSD and controls, this suggests that the increased activation in the controls is localized to the insula and is not a general global increase. PTSD, posttraumatic stress disorder.
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fig3: Reconstructed time courses from the right insula and left supramarginal gyrus to test the hypothesis of whether the insula is specifically recruited in unaffected individuals to maintain task performance. As the supramarginal gyrus does not show significant differences between PTSD and controls, this suggests that the increased activation in the controls is localized to the insula and is not a general global increase. PTSD, posttraumatic stress disorder.

Mentions: To test the hypothesis proposed by Simmons et al.19 that elite soldiers without PTSD show increased right insula activation, we reconstructed time courses in the right insula and statistically compared them between groups. To ensure that this was not due to an overall greater activation in one group, we also reconstructed time courses for both groups in the left posterior parietal cortex, the other key hub region for set-shifting. These time courses are contained in Figure 3 and show that the right insula is more activated in the control than the PTSD group, although both groups showed similar neural involvement. Further, it is clear that the suppressed involvement of right insula in the PTSD group is specific to right insula and is not seen in the left posterior parietal area, the other canonical set-shifting region.


Colour or shape: examination of neural processes underlying mental flexibility in posttraumatic stress disorder.

Pang EW, Sedge P, Grodecki R, Robertson A, MacDonald MJ, Jetly R, Shek PN, Taylor MJ - Transl Psychiatry (2014)

Reconstructed time courses from the right insula and left supramarginal gyrus to test the hypothesis of whether the insula is specifically recruited in unaffected individuals to maintain task performance. As the supramarginal gyrus does not show significant differences between PTSD and controls, this suggests that the increased activation in the controls is localized to the insula and is not a general global increase. PTSD, posttraumatic stress disorder.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4150239&req=5

fig3: Reconstructed time courses from the right insula and left supramarginal gyrus to test the hypothesis of whether the insula is specifically recruited in unaffected individuals to maintain task performance. As the supramarginal gyrus does not show significant differences between PTSD and controls, this suggests that the increased activation in the controls is localized to the insula and is not a general global increase. PTSD, posttraumatic stress disorder.
Mentions: To test the hypothesis proposed by Simmons et al.19 that elite soldiers without PTSD show increased right insula activation, we reconstructed time courses in the right insula and statistically compared them between groups. To ensure that this was not due to an overall greater activation in one group, we also reconstructed time courses for both groups in the left posterior parietal cortex, the other key hub region for set-shifting. These time courses are contained in Figure 3 and show that the right insula is more activated in the control than the PTSD group, although both groups showed similar neural involvement. Further, it is clear that the suppressed involvement of right insula in the PTSD group is specific to right insula and is not seen in the left posterior parietal area, the other canonical set-shifting region.

Bottom Line: MEG data were recorded and source localized to identify significant brain regions involved in the task.Activation latencies were obtained by analysing the time course of activation in each region.The control group showed a sequence of activity that involved dorsolateral frontal cortex, insula and posterior parietal cortices.

View Article: PubMed Central - PubMed

Affiliation: 1] Division of Neurology, Hospital for Sick Children, Toronto, ON, Canada [2] Neurosciences and Mental Health, SickKids Research Institute, Toronto, ON, Canada [3] Department of Paediatrics, University of Toronto, Toronto, ON, Canada.

ABSTRACT
Posttraumatic stress disorder (PTSD) is a mental disorder that stems from exposure to one or more traumatic events. While PTSD is thought to result from a dysregulation of emotional neurocircuitry, neurocognitive difficulties are frequently reported. Mental flexibility is a core executive function that involves the ability to shift and adapt to new information. It is essential for appropriate social-cognitive behaviours. Magnetoencephalography (MEG), a neuroimaging modality with high spatial and temporal resolution, has been used to track the progression of brain activation during tasks of mental flexibility called set-shifting. We hypothesized that the sensitivity of MEG would be able to capture the abnormal neurocircuitry implicated in PTSD and this would negatively impact brain regions involved in set-shifting. Twenty-two soldiers with PTSD and 24 matched control soldiers completed a colour-shape set-shifting task. MEG data were recorded and source localized to identify significant brain regions involved in the task. Activation latencies were obtained by analysing the time course of activation in each region. The control group showed a sequence of activity that involved dorsolateral frontal cortex, insula and posterior parietal cortices. The soldiers with PTSD showed these activations but they were interrupted by activations in paralimbic regions. This is consistent with models of PTSD that suggest dysfunctional neurocircuitry is driven by hyper-reactive limbic areas that are not appropriately modulated by prefrontal cortical control regions. This is the first study identifying the timing and location of atypical neural responses in PTSD with set-shifting and supports the model that hyperactive limbic structures negatively impact cognitive function.

Show MeSH
Related in: MedlinePlus