Current Biology
Volume 32, Issue 5, 14 March 2022, Pages 988-998.e6
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Article
Tuning alpha rhythms to shape conscious visual perception

https://doi.org/10.1016/j.cub.2022.01.003Get rights and content
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Highlights

  • Neural mechanisms of visual processing and its interpretation are dissociable

  • Different alpha parameters can be selectively modulated by rhythmic-TMS

  • Individual alpha frequency causally shapes objective accuracy

  • Alpha amplitude predicts subjective confidence and metacognitive abilities

Summary

It is commonly held that what we see and what we believe we see are overlapping phenomena. However, dissociations between sensory events and their subjective interpretation occur in the general population and in clinical disorders, raising the question as to whether perceptual accuracy and its subjective interpretation represent mechanistically dissociable events. Here, we uncover the role that alpha oscillations play in shaping these two indices of human conscious experience. We used electroencephalography (EEG) to measure occipital alpha oscillations during a visual detection task, which were then entrained using rhythmic-TMS. We found that controlling prestimulus alpha frequency by rhythmic-TMS modulated perceptual accuracy, but not subjective confidence in it, whereas controlling poststimulus (but not prestimulus) alpha amplitude modulated how well subjective confidence judgments can distinguish between correct and incorrect decision, but not accuracy.

These findings provide the first causal evidence of a double dissociation between alpha speed and alpha amplitude, linking alpha frequency to spatiotemporal sampling resources and alpha amplitude to the internal, subjective representation and interpretation of sensory events.

Keywords

conscious perception
alpha oscillations
alpha amplitude
alpha frequency
visual perception
confidence
rhythmic transcranial magnetic stimulation
alpha entrainment
electroencephalography

Data and code availability

The datasets generated during this study have been made publicly available through the Open Science Framework: https://osf.io/e4bnj/. Any additional information required to reanalyse the data reported in this paper is available from the lead contact upon request.

Cited by (0)

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These authors contributed equally

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Present address: Centro studi e ricerche in Neuroscienze Cognitive, Dipartimento di Psicologia, Alma Mater Studiorum – Università di Bologna, Campus di Cesena, 47521 Cesena, Italy

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Twitter: @VincenzoRomei

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Lead contact