Temporal kinetics of brain state effects on visual perception.

Fluctuations between attention and inattention shape sensory representation, yet the dynamics of these brain state transitions and whether inattention leads to a loss of sensory information remain unclear. We examined how focused wakefulness (ON state) and external inattention (OFF state) affect human perception and early visual responses. In two experiments, we investigated the temporal kinetics of brain state changes during stimulus processing and assessed fluctuations across extended periods of time. Using theta activity in MEG sensors, a classifier distinguished ON and OFF states on a single-trial level. Participants shifted from an ON to an OFF state as rapidly as two seconds. Visual target discrimination was comparable in both states, but reaction times were slower and more variable during the OFF state. Broad band high-frequency activity (BHA) recorded in MEG sensors covering the occipital cortex tracked target grating orientation. BHA was reduced during the OFF state but still tracked target grating orientation. Hence, participants were still able to distinguish sensory information highlighting the role of BHA in visual perception across cognitive brain states. Furthermore, BHA peak latency was longer than EEG-C1 latency, with the EEG-C1 component representing the initial visual feedforward sweep to V1. Taken together, these results suggest that BHA is involved in feedforward and feedback processing in the visual system.