Related Experiment Video
Updated: Feb 3, 2026

Network Analysis of the Default Mode Network Using Functional Connectivity MRI in Temporal Lobe Epilepsy
Published on: August 5, 2014
Brain network disintegration during sedation is mediated by the complexity of sparsely connected regions
I Pappas1, R M Adapa2, D K Menon2
1Division of Anaesthesia, School of Clinical Medicine, University of Cambridge, Box 93, Addenbrooke's Hospital, Biomedical Campus, Hills Road, Cambridge, CB2 0QQ, UK; Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Box 165, A Block, Level 3, Addenbrooke's Hospital, Biomedical Campus, Hills Road, Cambridge, CB2 0QQ, UK.
Abstract:
The precise mechanism of anaesthetic action on a neural level remains unclear. Recent approaches suggest that anaesthetics attenuate the complexity of interactions (connectivity) however evidence remains insufficient. We used tools from network and information theory to show that, during propofol-induced sedation, a collection of brain regions displayed decreased complexity in their connectivity patterns, especially so if they were sparsely connected. Strikingly, we found that, despite their low connectivity strengths, these regions exhibited an inordinate role in network integration. Their location and connectivity complexity delineated a specific pattern of sparse interactions mainly involving default mode regions while their connectivity complexity during the awake state also correlated with reaction times during sedation signifying its importance as a reliable indicator of the effects of sedation on individuals. Contrary to established views suggesting sedation affects only richly connected brain regions, we propose that suppressed complexity of sparsely connected regions should be considered a critical feature of any candidate mechanistic description for loss of consciousness.
More Related Videos
Related Concept Videos
Protein Networks
These interactions can be represented through maps depicting protein-protein interaction networks, represented as nodes and edges. Nodes are circles that are representative of a protein,...
Anatomy of the Brain: Major Regions
The cerebrum is the largest section of the brain and divides into left and right hemispheres, separated by a deep fissure. The cerebral outer layer of grey matter — the cerebral cortex — comprises elevations called gyri and shallow groves called sulci. The inner portion of white matter includes long nerve fibers known as axons, which connect...
Sedatives and Hypnotics: Overview
Sedative-hypnotics are categorized into barbiturates, benzodiazepines (BZDs), and non-benzodiazepines or Z-drugs. These drugs work by suppressing central nervous system activity, and this suppression is dose-dependent. Older sedative medications, like barbiturates, follow a linear curve in...
Sedatives and Hypnotics Drugs: Barbiturates
Sedatives and Hypnotics Drugs: Benzodiazepines
Benzodiazepines work by enhancing the effects of the inhibitory neurotransmitter GABA. They bind to the GABAA receptor, increasing its affinity for GABA, which opens chloride...
Network Covalent Solids
To break or to melt a covalent network solid, covalent bonds must be broken. Because covalent bonds are relatively strong, covalent network solids are typically...

