Whole-brain deactivations precede uninduced mind-blanking reports

Abstract

Mind-blanking (MB) is termed as the experience of inability to report mental contents. In contrast to other mental states, such as mind-wandering or sensory perceptions, the neural correlates of MB started getting elucidated only recently. A notable particularity that pertains to MB studies is the way MB is instructed for reports, like by deliberately asking participants to "empty their minds". Such instructions were shown to induce fMRI activations in frontal brain regions, typically associated with metacognition and self-evaluative processes, suggesting that MB may be a result of intentional mental content suppression. Here, we aim at examining this hypothesis by determining the neural correlates of MB without induction. Using fMRI combined with experience-sampling, univariate analysis of MB reports revealed deactivations in occipital, frontal, somatosensory, and thalamic areas, but no activations in prefrontal regions. In fact, a Bayesian region-of-interest analysis on areas previously shown to be implicated in MB provided evidence for frontal deactivations during MB reports in comparison to other mental states. Further contrast analysis between reports of MB and content oriented mental states also revealed deactivations in the L angular gyrus. We propose that these effects characterize a cortical profile of MB, where key cortical nodes are unable to communicate and formulate reportable content. Collectively, our results show that study instructions for MB may lead to cortical differences which provide different insights as to the underlying mechanisms leading to the phenomenology of MB.