Whole-Brain Deactivations Precede Uninduced Mind-Blanking Reports

Abstract

Mind-blanking (MB) is termed as the inability to report our immediate-past mental content. In contrast to mental states with reportable content, 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 reporting, 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 in 31 participants (22 female), univariate analysis of MB reports revealed deactivations in occipital, frontal, parietal, and thalamic areas, but no activations in prefrontal regions. These findings were confirmed using Bayesian region-of-interest analysis on areas previously shown to be implicated in induced MB, where we report evidence for frontal deactivations during MB reports compared with other mental states. Contrast analysis between reports of MB and content-oriented mental states also revealed deactivations in the left angular gyrus. We propose that these effects characterize a neuronal profile of MB, where key thalamocortical nodes are unable to communicate and formulate reportable content. Collectively, we show that study instructions for MB lead to differential neural activation. These results provide mechanistic insights linked to the phenomenology of MB and point to the possibility of MB being expressed in different forms.SIGNIFICANCE STATEMENTThis study explores how brain activity changes when individuals report unidentifiable thoughts, a phenomenon known as mind-blanking (MB). It aims to detect changes in brain activations and deactivations when MB is reported spontaneously, as opposed to the neural responses that have been previously reported when MB is induced. By means of brain imaging and experience-sampling, the study points to reduced brain activity in a wide number of regions, including those mesio-frontally which were previously detected as activated during induced MB. These results enhance our understanding of the complexity of spontaneous thinking and contribute to broader discussions on consciousness and reportable experience.

Neural correlates of pure presence

“…Far from being a state of dozing off or disconnection, PP is a state of intense, vivid, heightened consciousness. The signatures of PP states also differ from those of “mind-blanking” reported in meditation-naïve subjects, which seem to correspond to short bouts of drowsiness (31, 32). The phenomenology and neural signatures are thus remarkably different between “contentless” states such as PP that are meditation-induced (“cultivated”) and drowsy states that occur “in the wild” (33).…”

Two models of mind blanking

“…Subsequently, participants had the option to categorise their loss of focus as either mind blanking or mind wandering. The importance of inducing mind blanking in such a spontaneous and natural manner has been recently emphasised (Boulakis et al, 2023; Mortaheb et al, 2022, bioRxiv). The researchers examined both the phenomenological experience and the behavioural consequences of engaging in these reading comprehension tasks and concluded that mind blanking emerged as a unique mental state that occurs spontaneously.…”

“…It remains debatable what qualifies as exercising meta‐awareness about these seemingly contentless or inaccessible mental states, whether these exist in the first place, or whether these amount to mental states the content of which is merely not linguistically or conceptually accessible (as hypothesised by Kawagoe et al, 2019, Fell, 2022). In addition, exercising meta‐awareness about such mental states may also be determined by whether these states are intentional or spontaneous occurrences (Boulakis et al, 2023 bioRxiv). In this opinion article, we explore potential measurement techniques that could be employed to further study these mental states during which attention calls no perceptual input into conscious awareness.…”

Mind the blank: behavioral, experiential, and physiological signatures of absent-mindedness

“…The exact nature of mind blanking is still a matter of debate 12,13 and only a few studies have attempted to investigate its neural correlates. Some have reported a widespread deactivation of thalamic and cortical brain regions during spontaneous MB 14 and a more focal deactivation of the superior and inferior frontal gyri and hippocampus during intentional MB, whereas anterior cingulate cortex activation seemed to increase 15 . Others have reported an increase of functional connectivity, as measured by phase coherence metrics, during MB 16 .…”

“…Recent evidence suggests that both MW and MB could be explained by local sleep phenomena in the brain, but with different regional distributions 8 . Other accounts suggest that MB could arise from a specific pattern of neural (de)activations or functional connectivity, distinguishable from both task-focused and MW states 14,16 . To better understand the true nature of MB in respect to both task-focused and MW states, the neural distinctions of these mind states, if any, need to be further investigated.…”