Two Distinct Neuronal Networks Mediate the Awareness of Environment and of Self
Audrey Vanhaudenhuyse, Athena Demertzi, Manuel Schabus, Quentin Noirhomme, Serge Brédart, Melanie Boly, Christophe Phillips, Andrea Soddu, André Luxen, Gustave Moonen, Steven Laureys
Journal of Cognitive Neuroscience June 1, 2010 DOI: 10.1162/jocn.2010.21488 via OpenAlex
Summary
Resting brain activity reveals two anticorrelated cortical systems linked to conscious awareness: an extrinsic system (lateral fronto-parietal areas) associated with external awareness and an intrinsic system (medial brain areas) associated with internal awareness. In 31 healthy volunteers, external and internal awareness were significantly anticorrelated, with a mean switching frequency of 0.05 Hz, similar to BOLD fMRI slow oscillations. In 22 volunteers, fMRI showed that precuneus/posterior cingulate, anterior cingulate/mesiofrontal cortices, and parahippocampal areas (intrinsic system) correlated with internal awareness, while lateral fronto-parietal cortices (extrinsic system) correlated with external awareness.
Study at a glance
| Characteristics | Observational cohort Peer reviewed |
|---|---|
| Sample size | 31 |
| Population | Healthy volunteers |
| Topics | Default mode network |
| Keywords | Precuneus Posterior cingulate Neuroimaging Neuroscience Resting State FMRI |
| Citations | 460 |
| Key finding | External and internal awareness are anticorrelated and linked to distinct brain systems: intrinsic medial areas for internal awareness and extrinsic lateral fronto-parietal areas for external awareness. |
Abstract
Evidence from functional neuroimaging studies on resting state suggests that there are two distinct anticorrelated cortical systems that mediate conscious awareness: an "extrinsic" system that encompasses lateral fronto-parietal areas and has been linked with processes of external input (external awareness), and an "intrinsic" system which encompasses mainly medial brain areas and has been associated with internal processes (internal awareness). The aim of our study was to explore the neural correlates of resting state by providing behavioral and neuroimaging data from healthy volunteers. With no a priori assumptions, we first determined behaviorally the relationship between external and internal awareness in 31 subjects. We found a significant anticorrelation between external and internal awareness with a mean switching frequency of 0.05 Hz (range: 0.01-0.1 Hz). Interestingly, this frequency is similar to BOLD fMRI slow oscillations. We then evaluated 22 healthy volunteers in an fMRI paradigm looking for brain areas where BOLD activity correlated with "internal" and "external" scores. Activation of precuneus/posterior cingulate, anterior cingulate/mesiofrontal cortices, and parahippocampal areas ("intrinsic system") was linearly linked to intensity of internal awareness, whereas activation of lateral fronto-parietal cortices ("extrinsic system") was linearly associated with intensity of external awareness.