Being absent in the waking state: How mind blanking helps us understand ongoing thinking

Summary: When our mind goes blank, the brain enters a mode similar to that of deep sleep.

Source: University of Liege

Researchers at GIGA CRC In vivo Imaging at the University of Liège (Belgium), EPF Lausanne and University of Geneva publish a study showing that the phenomenology of mind blanking challenges the belief that the human mind is always thinking.

We generally assume that when we are awake our minds are full of thoughts. Like an ever-flowing river, we maintain our own dynamic mental stream: one thought can lead to another, relevant to what we do or don’t do, ebbing between our inner life and the outer environment. However, how can the brain sustain such a thought-related mode indefinitely?

A study just published in the Proceedings of the National Academy of Sciences points out that this is actually not possible and that our brain also has to “go offline” for a few moments, which we can experience as blank spaces in our heads.

Researchers from the University of Liège and EPF Lausanne and the University of Geneva re-analyzed a previously collected dataset in which healthy participants reported their mental state before hearing an acoustic probe (beep) while resting in the MRI scanner. Choices were perceptions of the environment, stimulus-dependent thoughts, stimulus-independent thoughts, and mental absence.

Functional images were collected during this experience sampling method. The researchers found that mind-blanking episodes were reported fairly infrequently compared to the other states, and that they rarely recurred over time.

Using machine learning, the researchers also found that during startling episodes, our brains were organized in such a way that all brain regions communicated with each other at the same time. This ultra-connected brain pattern was also characterized by a high amplitude of the global fMRI signal, which is a proxy for low cortical arousal.

In other words, when we report mind blanking, our brains appear to be in a similar mode to deep sleep, only we are awake.

“Mind blanking is a relatively new mental state in the study of spontaneous cognition. It opens up exciting pathways into the underlying biological mechanisms that occur during waking life. It could be that the boundaries between sleep and wakefulness are not as discrete as they seem after all,” says study leader Dr. Demertzi Athena, FNRS researcher at GIGA ULiège.

“The continuously and rapidly changing brain activity requires robust analytical methods to confirm the specific signature of mind blanking,” continues Dr. Van De Ville Dimitri.

The researchers claim that mind blanking’s rigid neurofunctional profile may account for the inability to report mental content, as the brain is unable to differentiate signals in an informative way.

While we wait for the underlying mechanisms to be elucidated, this work suggests that instantaneous, non-reportable mental events can occur during the waking state, creating lapses in consciousness as a prominent mental state during the ongoing experience.

About this news from neuroscientific research

Author: Didier Moreau
Source: University of Liege
Contact: Didier Moreau – University of Liège
Picture: The image is in the public domain

Original research: Closed access.
“Mind blanking is a distinct mental state associated with a recurrent brain profile of globally positive connectivity during ongoing mentation” by Demertzi, A et al. PNAS

See also

abstract

Mind blanking is a distinct mental state associated with a recurring brain profile of globally positive connectivity during ongoing mentation

Mind blanking (MB) is a waking state in which we do not report mental content. The phenomenology of MB challenges the perspective of a constantly thinking mind. Here we comprehensively characterize the neurobehavioural profile of MB with the aim of delineating its role during ongoing mentation.

Using functional MRI experience samples, we show that MB’s reportability is less frequent, faster, and with lower transition dynamics than other mental states, indicating its role as a transient mental relay.

Concerning its neural bases, we observed a 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 fidelity, suggesting that MB has a unique neuronal composition.

In fact, a global positive phase coherence pattern shows the closest resemblance to the connectivity patterns associated with MB reports. We interpret the rigid signaling architecture of this pattern as a barrier to content reportability, as the brain is unable to differentiate signals in an informative manner. Overall, we show that MB has a unique neurobehavioural profile, indicating that non-reportable mental events can occur during waking hours.

Our results contribute to the characterization of spontaneous mentality and pave the way for more mechanistic studies of MB phenomenology.