Schedule of Events | Search Abstracts | Invited Symposia | Symposia | Rising Stars | Poster Sessions | Data Blitz

Alpha phase dependence of orientation adaptation revealed by a closed-loop EEG system

Poster Session A - Saturday, March 7, 3:00 – 5:00 pm, Fairview/Kitsilano Ballrooms

Ryohei Nakayama¹, Kyuto Uno¹, Kaoru Amano¹; ¹The University of Tokyo

The phase of ongoing alpha oscillations (8–13 Hz) has been suggested to correlate with perceptual detection performance, consistent with reduced cortical excitability at the alpha peak. Phase dependence has also been reported for simultaneous spatial-contrast effects in orientation perception. The present study investigated whether alpha phase modulates adaptation-induced changes in orientation perception, using a closed-loop EEG system that predicted each participant’s alpha phase in real time. Individual alpha frequency (IAF) was estimated from eyes-open resting EEG collected in a prerun, which was defined as the frequency yielding maximal occipital alpha power. In each trial, a sequence of adaptor gratings tilted clockwise or counterclockwise was presented time-locked to either the alpha peak or trough. A test grating was subsequently presented likewise time-locked to the alpha peak or trough; its tilt was varied using a staircase in a two-alternative forced-choice (2AFC) judgment of clockwise versus counterclockwise tilt. Aftereffect magnitude was quantified as the shift in the test’s subjective verticality. The results from twelve participants showed a significant difference in repulsive aftereffect by the adaptor’s phase. No reliable effect was observed for the test’s phase. These findings suggest that alpha phase influences not only instantaneous spatial interactions but also history-dependent dynamics in orientation perception.

Topic Area: PERCEPTION & ACTION: Vision