Self-regulation of the posterior-frontal brain activity with real-time fMRI neurofeedback to influence conscious perception

Abstract The Global Neuronal Workspace (GNW) hypothesis states that the visual percept is available to conscious awareness only if recurrent long-distance interactions among distributed brain regions activate neural circuitry extending from posterior regions to prefrontal regions above a certain excitation threshold. To directly test this hypothesis, we trained human participants to increase blood oxygenation level-dependent (BOLD) signals with real-time functional magnetic resonance imaging (rtfMRI) based neurofeedback simultaneously in four specific regions of the occipital, temporal, insular and prefrontal parts of the brain. Specifically, we hypothesized that up-regulation of the mean BOLD activity in the posterior-frontal brain regions lowers the perceptual threshold for visual stimuli, while down-regulation raises the threshold. Our results showed that participants were able to perform up-regulation of the posterior-frontal brain activity but not down-regulation. Furthermore, the up-regulation training led to a significant reduction of the visual perceptual threshold, but no significant change of perceptual threshold was observed after down-regulation training. These findings partially support the GNW hypothesis of consciousness perception, to the extent that up-regulation of the posterior-frontal regions improves conscious awareness of stimuli. However, further questions as to whether the posterior-frontal regions can be down-regulated at all, and whether down-regulation raises the perceptual threshold remain unanswered.