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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 left posterior cingulate, an area that was identified as active in this set-shifting task, although not typically seen on this kind of protocol. For intra-dimensional shifting, the PTSD group shows significantly greater activation in an early time window. For the extra-dimensional shifting, the between-groups difference is no longer significant due to the increased activation in this area in the military controls. Possibly, this increased activation reflects the increasing difficulty of the extra-dimensional shift, which is manifest as a stress-related increase in paralimbic regions for the controls. PTSD, posttraumatic stress disorder.
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fig1: Reconstructed time courses from the left posterior cingulate, an area that was identified as active in this set-shifting task, although not typically seen on this kind of protocol. For intra-dimensional shifting, the PTSD group shows significantly greater activation in an early time window. For the extra-dimensional shifting, the between-groups difference is no longer significant due to the increased activation in this area in the military controls. Possibly, this increased activation reflects the increasing difficulty of the extra-dimensional shift, which is manifest as a stress-related increase in paralimbic regions for the controls. PTSD, posttraumatic stress disorder.

Mentions: In Table 2, there are a number of cells coded with the colour brown. These cells indicate neural regions that are not typically seen in a set-shifting task. Specifically, the left posterior cingulate showed prominent and significant activation in both groups for both types of set shifting. To explore the involvement of the left posterior cingulate, the time course of activation in this location was reconstructed for the two groups and tested for differences. Figure 1 reveals that the posterior cingulate was activated earlier and to a greater extent in the PTSD as compared with control soldiers.


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 left posterior cingulate, an area that was identified as active in this set-shifting task, although not typically seen on this kind of protocol. For intra-dimensional shifting, the PTSD group shows significantly greater activation in an early time window. For the extra-dimensional shifting, the between-groups difference is no longer significant due to the increased activation in this area in the military controls. Possibly, this increased activation reflects the increasing difficulty of the extra-dimensional shift, which is manifest as a stress-related increase in paralimbic regions for the controls. PTSD, posttraumatic stress disorder.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig1: Reconstructed time courses from the left posterior cingulate, an area that was identified as active in this set-shifting task, although not typically seen on this kind of protocol. For intra-dimensional shifting, the PTSD group shows significantly greater activation in an early time window. For the extra-dimensional shifting, the between-groups difference is no longer significant due to the increased activation in this area in the military controls. Possibly, this increased activation reflects the increasing difficulty of the extra-dimensional shift, which is manifest as a stress-related increase in paralimbic regions for the controls. PTSD, posttraumatic stress disorder.
Mentions: In Table 2, there are a number of cells coded with the colour brown. These cells indicate neural regions that are not typically seen in a set-shifting task. Specifically, the left posterior cingulate showed prominent and significant activation in both groups for both types of set shifting. To explore the involvement of the left posterior cingulate, the time course of activation in this location was reconstructed for the two groups and tested for differences. Figure 1 reveals that the posterior cingulate was activated earlier and to a greater extent in the PTSD as compared with control soldiers.

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