Occipital MEG Activity in the Early Time Range (<300 ms) Predicts Graded Changes in Perceptual Consciousness.
Lau M Andersen, Michael N Pedersen, Kristian Sandberg, Morten Overgaard
Cerebral cortex (New York, N.Y. : 1991) June 1, 2016 DOI: 10.1093/cercor/bhv108 (opens in new tab) via PubMed
Summary
AI-generated from the abstractTwo brain signals have been studied as possible markers of conscious perception: an early one from the back of the head (130-320 ms after seeing something) and a late one from the front (320-510 ms). Recent work suggests the late signal may also reflect expectations, attention, and task demands, not just consciousness. Using magnetoencephalography and multivariate decoding, this study directly compared how well each signal predicts whether someone consciously perceives a stimulus. Occipital (back-of-head) sources in the early time window were significantly more accurate at decoding consciousness than frontal sources in either time window. These results challenge theories that emphasize frontal brain regions for conscious perception.
Study at a glance
| Characteristics | Observational cohort Peer reviewed |
|---|---|
| Keywords | Classification Consciousness Magnetoencephalography Perception |
| Key finding | Occipital sources during the early time range (130-320 ms) were significantly more accurate in decoding perceptual consciousness than frontal sources during both early and late time ranges. |
Abstract
Two electrophysiological components have been extensively investigated as candidate neural correlates of perceptual consciousness: An early, occipitally realized component occurring 130-320 ms after stimulus onset and a late, frontally realized component occurring 320-510 ms after stimulus onset. Recent studies have suggested that the late component may not be uniquely related to perceptual consciousness, but also to sensory expectations, task associations, and selective attention. We conducted a magnetoencephalographic study; using multivariate analysis, we compared classification accuracies when decoding perceptual consciousness from the 2 components using sources from occipital and frontal lobes. We found that occipital sources during the early time range were significantly more accurate in decoding perceptual consciousness than frontal sources during both the early and late time ranges. These results are the first of its kind where the predictive values of the 2 components are quantitatively compared, and they provide further evidence for the primary importance of occipital sources in realizing perceptual consciousness. The results have important consequences for current theories of perceptual consciousness, especially theories emphasizing the role of frontal sources.