Reduced occipital alpha power indexes enhanced excitability rather than improved visual perception

Area of Science:

• Neuroscience
• Visual Perception
• Cognitive Science

Background:

• Prestimulus occipital alpha-band activity influences perception of near-threshold visual stimuli.
• Variability in perception of constant suprathreshold stimuli occurs in phenomena like the double-flash illusion (DFI) and fusion effect (FE).

Purpose of the Study:

• To investigate the role of prestimulus power fluctuations in the DFI and FE.
• To determine if reduced alpha power universally promotes veridical visual perception.

Main Methods:

• Recorded prestimulus occipital electroencephalography (EEG) activity.
• Analyzed the relationship between alpha and gamma power and perception in DFI and FE.

Main Results:

• Reduced prestimulus occipital alpha power predicted the perception of two stimuli in both FE (veridical) and DFI (illusory).
• Enhanced prestimulus occipital gamma-band power predicted two-stimulus perception in the DFI.
• Findings indicate reduced alpha power may reflect enhanced neural excitability rather than solely improved processing.

Conclusions:

• Prestimulus alpha power fluctuations play a role in both veridical and illusory visual perception.
• Reduced alpha power is associated with enhanced neural excitability, not necessarily improved visual processing.
• Prestimulus gamma-band activity may also contribute to specific visual illusions.