Transcranial Alternating Current Stimulation over Frontal Eye Fields Mimics Attentional Modulation of Visual...

Area of Science:

• Neuroscience
• Cognitive Science
• Visual Perception

Background:

• Attentional control modulates sensory processing via neural alpha oscillations.
• The precise mechanisms linking alpha oscillations to perception and top-down attention remain unclear.

Purpose of the Study:

• To investigate the causal role of frontal eye fields (FEFs) alpha oscillations in top-down visual processing regulation.
• To test if alpha oscillations in FEFs are essential for attentional preparation in visual tasks.

Main Methods:

• Sham-controlled, intermittent transcranial alternating current stimulation (tACS) at 10 Hz (alpha) or 40 Hz (gamma) over bilateral FEFs.
• Measurement of psychometric functions for contrast perception in a visual discrimination task.
• Application of a novel linear mixed modeling approach to control for stimulation side effects.

Main Results:

• Alpha frequency tACS over FEFs reduced the psychometric function slope.
• This resulted in enhanced perception of subthreshold contrast and impaired perception of superthreshold contrast.
• Statistical control for side effects strengthened the observed perceptual effects.

Conclusions:

• Alpha tACS over FEFs mimics endogenous attention by strengthening alpha-band fronto-occipitoparietal network activity.
• This modulation may enhance phasic gating in the occipitoparietal cortex, increasing trial-by-trial threshold variability.
• Alpha oscillations in FEFs play a causal role in regulating visual perception through top-down attentional mechanisms.