Summary: When our minds go blank, the brain enters into a similar mode as it does during deep sleep.
Source: University of Liege
Researchers from the GIGA CRC In vivo Imaging at the University of Liège (Belgium), the EPF Lausanne and the University of Geneva publish a study that shows that the phenomenology of “mind blanking” challenges the belief that the human mind is always thinking.
We generally consider that our mind is full of thoughts when we are awake. Like a river stream always running, similarly we entertain our own dynamic mental stream: a thought can lead to another, relevant to what we do or not, ebbing between our inner life and the outer environment. How can the brain sustain such a thought-related mode constantly, though?
A study just published in the Proceedings of the National Academy of Sciences indicates that it actually cannot, and that our brains also need to “go offline” for some moments, which we can experience as blanks in the mind.
Researchers from the University of Liège and EPF Lausanne & University of Geneva re-analyzed a previously collected dataset where healthy participants were reporting their mental state as this was before hearing an auditory probe (beep) while resting in the MRI scanner. The choices were among perceptions of the environment, stimulus-dependent thoughts, stimulus-independent thoughts, and mental absences.
Functional images were being collected during this experience-sampling method. The researchers found that mind blanking episodes were reported quite rarely compared to the other states, and that they were re-appearing also scarcely across time.
Using machine learning, the researchers further found that our brains during mind-blanking episodes organized in a way where all brain regions were communicating with each other at the same time. This ultra-connected brain pattern was further characterized by high amplitude of the fMRI global signal, which is a proxy of low cortical arousal.
In other words, when reporting mind blanking our brains seem to be in a mode similar to that of deep sleep, only that we are awake.
“Mind blanking is a relatively new mental state within the study of spontaneous cognition. It opens exciting avenues about the underlying biological mechanisms that happen during waking life. It might be that the boundaries of sleep and wakefulness might not be that discrete as they appear to be after all”, says the principal investigator Dr. Demertzi Athena, FNRS researcher at GIGA ULiège.
“The continuously and rapidly changing brain activity requires robust analysis methods to confirm the specific signature of mind blanking”, continues Dr. Van De Ville Dimitri.
The researchers claim that the rigid neurofunctional profile of mind blanking could account for the inability to report mental content due to the brain’s inability to differentiate signals in an informative way.
While waiting for the underlying mechanisms to be illuminated, this work suggests that instantaneous non-reportable mental events can happen during wakefulness, setting mind blanks as a prominent mental state during ongoing experience.
Mind blanking is a distinct mental state linked to a recurrent brain profile of globally positive connectivity during ongoing mentation
Mind blanking (MB) is a waking state during which we do not report any mental content. The phenomenology of MB challenges the view of a constantly thinking mind. Here, we comprehensively characterize the MB’s neurobehavioral profile with the aim to delineate its role during ongoing mentation.
Using functional MRI experience sampling, we show that the reportability of MB is less frequent, faster, and with lower transitional dynamics than other mental states, pointing to its role as a transient mental relay.
Regarding its neural underpinnings, we observed higher global signal amplitude during MB reports, indicating a distinct physiological state. Using the time-varying functional connectome, we show that MB reports can be classified with high accuracy, suggesting that MB has a unique neural composition.
Indeed, a pattern of global positive-phase coherence shows the highest similarity to the connectivity patterns associated with MB reports. We interpret this pattern’s rigid signal architecture as hindering content reportability due to the brain’s inability to differentiate signals in an informative way. Collectively, we show that MB has a unique neurobehavioral profile, indicating that nonreportable mental events can happen during wakefulness.
Our results add to the characterization of spontaneous mentation and pave the way for more mechanistic investigations of MB’s phenomenology.