In the scope of project 204/18 – Boosting WM capacity by strengthening the oscillatory functional fronto-parietal pathway, Vincenzo Romei et al published in the journal Current Biology, the paper Tuning alpha rhythms to shape conscious visual perception with the following 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.
“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.”
