Spatial attention is not affected by alpha or beta transcranial alternating current stimulation: A registered report

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Human Brain Activity

Background:

• Event-related changes in alpha activity over sensory cortices are linked to spatial attention allocation.
• These alpha changes are lateralized, with increased power ipsilateral and decreased power contralateral to the attended space.
• The causal role of alpha oscillations in attention allocation remains unclear.

Purpose of the Study:

• To determine if alpha oscillatory activity causally influences spatial attention.
• To investigate whether ipsilateral alpha increases or contralateral decreases drive attentional allocation.
• To test the causal link between alpha activity modulation and tactile attention performance.

Main Methods:

• Utilized transcranial alternating current stimulation (tACS) to modulate alpha activity in the somatosensory cortex.
• Employed endogenous and exogenous tactile attention tasks to measure performance.
• Included sham and beta stimulation conditions as controls for alpha stimulation.

Main Results:

• Behavioral findings for endogenous (cue facilitation) and exogenous (inhibition of return) attention tasks were replicated across all stimulation conditions.
• No significant effects of alpha stimulation on tactile attention performance were observed.
• Bayes-factor analysis provided strong support for the null hypothesis, indicating no causal link.

Conclusions:

• Modulation of alpha activity via tACS does not appear to causally impact tactile spatial attention.
• The observed alpha activity changes during attention may be epiphenomenal rather than causal.
• This study contributes robust evidence to the ongoing debate on brain stimulation efficacy for attention.