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Deactivation of the default mode network as a marker of impaired consciousness: an fMRI study.

Crone JS, Ladurner G, Höller Y, Golaszewski S, Trinka E, Kronbichler M - PLoS ONE (2011)

Bottom Line: Results show that deactivation in medial regions is reduced in MCS and absent in UWS patients compared to healthy controls.Interestingly, all patients who deactivated during speech processing (except for one) showed activation in left frontal regions which are associated with conscious processing.Our results indicate that deactivation of the DMN can be associated with the level of consciousness by selecting those who are able to interrupt ongoing introspective processes.

View Article: PubMed Central - PubMed

Affiliation: Neuroscience Institute and Centre for Neurocognitive Research, Christian-Doppler-Clinic, Paracelsus Private Medical University, Salzburg, Austria. j.crone@neurocognition.org

ABSTRACT
Diagnosis of patients with a disorder of consciousness is very challenging. Previous studies investigating resting state networks demonstrate that 2 main features of the so-called default mode network (DMN), metabolism and functional connectivity, are impaired in patients with a disorder of consciousness. However, task-induced deactivation--a third main feature of the DMN--has not been explored in a group of patients. Deactivation of the DMN is supposed to reflect interruptions of introspective processes. Seventeen patients with unresponsive wakefulness syndrome (UWS, former vegetative state), 8 patients in minimally conscious state (MCS), and 25 healthy controls were investigated with functional magnetic resonance imaging during a passive sentence listening task. Results show that deactivation in medial regions is reduced in MCS and absent in UWS patients compared to healthy controls. Moreover, behavioral scores assessing the level of consciousness correlate with deactivation in patients. On single-subject level, all control subjects but only 2 patients in MCS and 6 with UWS exposed deactivation. Interestingly, all patients who deactivated during speech processing (except for one) showed activation in left frontal regions which are associated with conscious processing. Our results indicate that deactivation of the DMN can be associated with the level of consciousness by selecting those who are able to interrupt ongoing introspective processes. In consequence, deactivation of the DMN may function as a marker of consciousness.

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Strength of deactivation during sentence processing between groups.Image displays deactivation in healthy controls, patients in minimally conscious state (MCS), and patients with unresponsive wakefulness syndrome (UWS) in the 4 main regions of the DMN: medial parietal regions; medial frontal regions; right middle temporal gyrus (rMTG); left middle temporal gyrus (lMTG). Bars represent mean contrast estimates and standard error of mean.
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pone-0026373-g002: Strength of deactivation during sentence processing between groups.Image displays deactivation in healthy controls, patients in minimally conscious state (MCS), and patients with unresponsive wakefulness syndrome (UWS) in the 4 main regions of the DMN: medial parietal regions; medial frontal regions; right middle temporal gyrus (rMTG); left middle temporal gyrus (lMTG). Bars represent mean contrast estimates and standard error of mean.

Mentions: Results of the ROI analysis are displayed in Table 2 and Figure 2. A main effect of group for contrast estimates was detected in medial parietal regions and in the rMTG. The control group showed significant deactivation in both medial regions and in the rMTG. The MCS and UWS group demonstrated no significant deactivation. Comparing contrast estimates between groups, control subjects demonstrated more deactivation in rMTG and lMTG compared to patients in MCS; and more deactivation in medial parietal regions, in medial frontal regions, and in the rMTG compared to patients with UWS. Between MCS and UWS patients, a trend towards differences in contrast estimates could be detected in medial parietal regions but was not significant when adjusting for multiple corrections. Results concerning the number of deactivated voxels did not offer any additional information (data not shown).


Deactivation of the default mode network as a marker of impaired consciousness: an fMRI study.

Crone JS, Ladurner G, Höller Y, Golaszewski S, Trinka E, Kronbichler M - PLoS ONE (2011)

Strength of deactivation during sentence processing between groups.Image displays deactivation in healthy controls, patients in minimally conscious state (MCS), and patients with unresponsive wakefulness syndrome (UWS) in the 4 main regions of the DMN: medial parietal regions; medial frontal regions; right middle temporal gyrus (rMTG); left middle temporal gyrus (lMTG). Bars represent mean contrast estimates and standard error of mean.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3198462&req=5

pone-0026373-g002: Strength of deactivation during sentence processing between groups.Image displays deactivation in healthy controls, patients in minimally conscious state (MCS), and patients with unresponsive wakefulness syndrome (UWS) in the 4 main regions of the DMN: medial parietal regions; medial frontal regions; right middle temporal gyrus (rMTG); left middle temporal gyrus (lMTG). Bars represent mean contrast estimates and standard error of mean.
Mentions: Results of the ROI analysis are displayed in Table 2 and Figure 2. A main effect of group for contrast estimates was detected in medial parietal regions and in the rMTG. The control group showed significant deactivation in both medial regions and in the rMTG. The MCS and UWS group demonstrated no significant deactivation. Comparing contrast estimates between groups, control subjects demonstrated more deactivation in rMTG and lMTG compared to patients in MCS; and more deactivation in medial parietal regions, in medial frontal regions, and in the rMTG compared to patients with UWS. Between MCS and UWS patients, a trend towards differences in contrast estimates could be detected in medial parietal regions but was not significant when adjusting for multiple corrections. Results concerning the number of deactivated voxels did not offer any additional information (data not shown).

Bottom Line: Results show that deactivation in medial regions is reduced in MCS and absent in UWS patients compared to healthy controls.Interestingly, all patients who deactivated during speech processing (except for one) showed activation in left frontal regions which are associated with conscious processing.Our results indicate that deactivation of the DMN can be associated with the level of consciousness by selecting those who are able to interrupt ongoing introspective processes.

View Article: PubMed Central - PubMed

Affiliation: Neuroscience Institute and Centre for Neurocognitive Research, Christian-Doppler-Clinic, Paracelsus Private Medical University, Salzburg, Austria. j.crone@neurocognition.org

ABSTRACT
Diagnosis of patients with a disorder of consciousness is very challenging. Previous studies investigating resting state networks demonstrate that 2 main features of the so-called default mode network (DMN), metabolism and functional connectivity, are impaired in patients with a disorder of consciousness. However, task-induced deactivation--a third main feature of the DMN--has not been explored in a group of patients. Deactivation of the DMN is supposed to reflect interruptions of introspective processes. Seventeen patients with unresponsive wakefulness syndrome (UWS, former vegetative state), 8 patients in minimally conscious state (MCS), and 25 healthy controls were investigated with functional magnetic resonance imaging during a passive sentence listening task. Results show that deactivation in medial regions is reduced in MCS and absent in UWS patients compared to healthy controls. Moreover, behavioral scores assessing the level of consciousness correlate with deactivation in patients. On single-subject level, all control subjects but only 2 patients in MCS and 6 with UWS exposed deactivation. Interestingly, all patients who deactivated during speech processing (except for one) showed activation in left frontal regions which are associated with conscious processing. Our results indicate that deactivation of the DMN can be associated with the level of consciousness by selecting those who are able to interrupt ongoing introspective processes. In consequence, deactivation of the DMN may function as a marker of consciousness.

Show MeSH
Related in: MedlinePlus