Test for Inhibition hypothesis and EEG alpha rhythm in visual detection: preliminary findings

Poster Session F - Tuesday, April 16, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

DR. Kyongje Sung¹, Mariam Aljaafari¹, Nusaibah Al Ameri¹, Claudine Habak¹; ¹Emirates College for Advanced Education, Abu Dhabi, UAE

The cortical areas related to a given task show attenuated alpha power (8-13 Hz), and those unrelated to the task show strong alpha. Some suggested alpha represents the electrophysiologic mechanism that activates/suppresses cortical activities. In this preliminary study, we tested the causality claim (i.e., inhibition hypothesis), hypothesizing that if it held, alpha power would be higher in the high noise condition (difficult) than in the low or no noise (easy) conditions. Ten adults (4 males) participated: they viewed a movie consisting of a baseline blank screen (2s), followed by static random noise (1.6, 1.8, 2.2s). Then, with the noise on the screen, a static Gabor target (4 angles) gradually increased in intensity (3.2s), to a maximum (1.6s), then gradually decreased (3.2s), and the noise only (2s). Participants pressed keys to indicate the appearance and disappearance of the target. Noise level was manipulated through luminance modulation and target luminance was constant across conditions. Trials were randomly intermixed into three blocks. A VIEWPixx/EEG monitor generated movie frame-based event markers, and EEG signals were recorded using a 64-channel EEG system (R-net with actiChamp Plus, Brain Products). All channel analyses showed that alpha power attenuated at the onset of the noise on average, with no power difference across conditions. The difference in alpha power attenuation was observable between conditions only when the target was seen, with the largest power reduction in the difficult condition. These tentative results are not in line with the causality claim for alpha.

Topic Area: ATTENTION: Spatial