Pre-stimulus alpha oscillation and post-stimulus cortical activity differ in localization between consciously perceived and missed near-threshold somatosensory stimuli.
The European journal of neuroscience August 1, 2021 Jun-Ichi Uemura, Aiko Hoshino, Go Igarashi et al.
Conscious perception of a near-threshold somatosensory stimulus depends on both pre-stimulus brain state and post-stimulus cortical activity, but their roles vary across cortical areas. Using magnetoencephalography during a detection task, researchers found that somatosensory hierarchical processing areas, prefrontal areas, and default mode network regions showed stronger post-stimulus activity for consciously perceived trials. However, activity in the primary somatosensory area (SI) was independent of conscious perception during early stimulus processing. Pre-stimulus alpha oscillations only in SI predicted conscious perception. These results suggest that bottom-up somatosensory information flow following SI and top-down modulation via pre-stimulus alpha fluctuations in SI are crucial for conscious perception.