Investigating the role of beta and gamma tACS in visual processing and conscious perception
Neuroscience of Consciousness December 27, 2025 Yayla A Ilksoy, Alethia de la Fuente, Jacobo Sitt et al.
In a backward masking task, participants received transcranial alternating current stimulation (tACS) at 20 Hz or 40 Hz to test whether beta- or gamma-band oscillations causally influence conscious and unconscious visual perception. Contrary to expectations, 20 Hz-tACS selectively impaired objective visibility (correct categorization of masked targets) but not subjective visibility (self-reported conscious perception). 40 Hz-tACS showed no effect. Local beta power increased after 20 Hz-tACS, but inter-areal beta synchrony may have been disrupted. The findings suggest a potential causal role for beta-band activity in visual perception, particularly for objective discrimination, and point to future studies using other stimulation methods or model organisms.