Dual-Site Beta tACS over the rIFG and preSMA Induced Phase-Specific
Changes in Functional Connectivity but Not Response Inhibition
Performance in Older Adults
Abstract
Research suggests that changes in functional connectivity contribute to
age-related declines in response inhibition. Through a double-blind
crossover study, we investigated the effects of dual-site beta
transcranial alternating current stimulation (tACS) over the right
inferior frontal gyrus (rIFG) and pre-supplementary motor area (preSMA)
on functional connectivity measured with electroencephalography and
response inhibition (stop-signal task performance) in 15 older (aged
61-79 years) and 18 young (aged 18-34 years) adults. Two tACS conditions
were administered in separate sessions: in-phase tACS, where electrical
currents delivered to rIFG and preSMA had a 0° phase difference, and
anti-phase tACS, where currents had a 180° phase difference.
Resting-state beta band rIFG-preSMA connectivity significantly increased
after in-phase tACS for older and young adults, and decreased after
anti-phase tACS for older adults. This shows that tACS can modulate
rIFG-preSMA connectivity in a phase-specific manner in the aging brain.
However, response inhibition significantly improved after both in- and
anti-phase tACS for young and older adults, indicating that inhibitory
performance might not be directly regulated by resting-state rIFG-preSMA
phase connectivity.