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Deactivation of the Default Mode Network as a Marker of Impaired Consciousness: An fMRI Study

J. Crone, G. Ladurner, Y. Höller, S. Golaszewski, E. Trinka, M. Kronbichler

PLoS One October 19, 2011 DOI: 10.1371/journal.pone.0026373 (opens in new tab)

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Study at a glance

AI-extracted from the abstract
Characteristics Observational case-control study Peer reviewed
Sample size 50
Population 17 patients with unresponsive wakefulness syndrome, 8 patients in minimally conscious state, and 25 healthy controls
Topics Default mode network Philosophy of mind
Key findings Task-induced deactivation of medial default mode network regions was reduced in minimally conscious patients and absent in unresponsive wakefulness syndrome patients compared with healthy controls, and behavioral consciousness scores correlated with deactivation. The authors argue that deactivation of the default mode network may function as a marker of consciousness by identifying patients able to interrupt ongoing introspective processes.

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.

Comparable studies

Other observational and cohort studies on default mode network, most cited first.

Study Year Design Participants
A default mode of brain function Normal adult human brain 2001 Observational study
Resting-State Functional Connectivity Reflects Structural Connectivity in the Default Mode Network Healthy subjects 2008 Observational cohort
Meditation experience is associated with increased cortical thickness Participants with extensive Insight meditation experience and matched controls 2005 Observational cohort n = 20
Meditation experience is associated with differences in default mode network activity and connectivity Experienced meditators and matched meditation-naive controls 2011 Observational cohort
The precuneus/posterior cingulate cortex plays a pivotal role in the default mode network: Evidence from a partial correlation network analysis Healthy subjects 2008 Observational study

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Default mode network Philosophy of mind