18 Scopus citations

Abstract

The current state of empirical investigations refers to consciousness as an all-or-none phenomenon. However, a recent theoretical account opens up this perspective by proposing a partial level (between nil and full) of conscious perception. In the well-studied case of single-word reading, short-lived exposure can trigger incomplete word-form recognition wherein letters fall short of forming a whole word in one's conscious perception thereby hindering word-meaning access and report. Hence, the processing from incomplete to complete word-form recognition straightforwardly mirrors a transition from partial to full-blown consciousness. We therefore hypothesized that this putative functional bottleneck to consciousness (i.e. the perceptual boundary between partial and full conscious perception) would emerge at a major key hub region for word-form recognition during reading, namely the left occipito-temporal junction. We applied a real-time staircase procedure and titrated subjective reports at the threshold between partial (letters) and full (whole word) conscious perception. This experimental approach allowed us to collect trials with identical physical stimulation, yet reflecting distinct perceptual experience levels. Oscillatory brain activity was monitored with magnetoencephalography and revealed that the transition from partial-to-full word-form perception was accompanied by alpha-band (7-11. Hz) power suppression in the posterior left occipito-temporal cortex. This modulation of rhythmic activity extended anteriorly towards the visual word form area (VWFA), a region whose selectivity for word-forms in perception is highly debated. The current findings provide electrophysiological evidence for a functional bottleneck to consciousness thereby empirically instantiating a recently proposed partial perspective on consciousness. Moreover, the findings provide an entirely new outlook on the functioning of the VWFA as a late bottleneck to full-blown conscious word-form perception.

Original languageEnglish
Pages (from-to)33-45
Number of pages13
JournalNeuroImage
Volume78
DOIs
StatePublished - Sep 2013

Funding

The present work was supported by both the European Science Foundation's European Young Investigator Award Program , and by the French Ministry scholarship. The authors wish to thank Bram Daams and Sander Berends for MEG technical support, as well as Jan-Mathijs Schoffelen and Stan van Pelt for their advice on the analysis scheme.

FundersFunder number
French Ministry
European Science Foundation

    Keywords

    • Alpha-band
    • Consciousness
    • MEG
    • Neuronal oscillations
    • Reading
    • VWFA

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