Your mind really can go blank when you're awake. Here's what happens in your brain

The human mind really can go blank during consciousness, according to a new review that challenges the assumption people experience a constant flow of thoughts when awake. Instead, there are moments when the human mind seems empty of any content, and people seemingly aren’t thinking of anything at all. “Mind blanking” is a newly explored and distinct mental state that isn’t the same as a lapse of attention or a wandering mind, the research team writes. People aren’t thinking about something else. Instead, “our minds go ‘nowhere’ because they seem to lack content.” Mind blanking is a common, daily life phenomenon linked to changes in states of arousal, the researchers report, and tends to occur towards the end of long and demanding attention tasks like exams, when people are sleep deprived or after an intense workout. Meaning that, “when the brain is in a high- or low-arousal state, a mind blank is more likely to occur.” In experiments with healthy volunteers, the brain shows signs of “deactivation” and an increase in sleep-like slow brain waves during a reported mind blank. Heart rates and pupil sizes decrease. A part of the brain appears asleep, “which may represent a state of ‘local sleep’ rather than outright sleep,” the researchers write. The experience has been described as a “lack of conscious awareness,” they noted, during which “the individual is not focally aware of any stimuli, either internal or external,” a particularly dangerous state if it occurs during high-risk, inopportune moments, like driving. It may be the result of glitches in memory, language or attention. In experiments, people report feeling sleepier, and more sluggish, and they make more errors on attention tasks moments before their minds go “nowhere.” While some people never report mind blanking, adults and children with ADHD (attention deficient hyperactivity disorder) report the experience more frequently than “neurotypical people,” the researchers said. “Mind going blank” is also one of the core symptoms of generalized anxiety disorder. It’s also related to strokes, seizures, traumatic brain injuries and an “ultra-rare” sleep disorder (Kleine-Levin syndrome) that affects primarily teenage boys and that causes them to sleep up to 20 hours a day. “The experience of a ‘blank mind’ is as intimate and direct as that of bearing thoughts,” the team of neuroscientists and philosophers write. It’s not entirely clear what these “blanks” represent, they said. However, “We sought to better understand mind blanking by parsing through 80 relevant research articles — including some of our own in which we recorded participants’ brain activity when they were reporting that they were ‘thinking of nothing,'” Athena Demertzi, of the University of Liege, Belgium, said in a press release. If scientists can better understand what’s happening in the brain, and if people could learn how to deliberately, instead of randomly, not think about anything, it could be an interesting strategy for dealing with anxiety, negative thoughts or other unpleasant emotions, lead author Thomas Andrillon, a cognitive neuroscientist at the Paris Brain Institute, said in an interview with National Post. “It could represent a tool we could use to be more relaxed and improve our wellbeing.” People assume Descartes’ Cogito, ergo sum goes both ways, Andrillon said: “‘I think, therefore I am’ and ‘I am, therefore I think.’ “We challenge the latter by showing that people can be conscious without thinking about something in particular.” “Most of the time, by definition, mind blanking will go unnoticed, since there is no content associated with it,” Andrillon added. “We didn’t realize there was a blank. “But sometimes, there are moments in your everyday life where we can introspect a bit about our own stream of thoughts and we can notice that there has been a gap,” like when people walk into a room and can’t quite remember how they got there, or why they’re even there. “It’s pretty frequent in everyday life,” Andrillon said. There’s no “definitive guidance” on how to reliably measure mind blanking, the researchers write. But their review found that mind blanking is associated with specific changes in brain dynamics during “no-thinking” moments. In his own experiments, Andrillon has tracked, via EEG and special MRI imaging, the brain activity of healthy volunteers performing different tasks. When people are interrupted randomly and asked the contents of their thoughts — “what are you thinking?” — mind blanking is typically reported five to 20 per cent of the time. The researchers have to rely on people’s subjective experience. “Obviously, we need to trust what they are telling us,” Andrillon said. “But it doesn’t look like these mind blanking reports are completely random — they have a specific behavioural and physiological signature” different from what they see when people report another mind state, like that they were thinking about something else, and not the task. Brain rhythms tend to slow when people mind blank, similiar to the brain changes that occur just before the onset of sleep, again because of lower arousal. That suggests there are moments during the day “where parts of the brain start showing signs of sleeping, resulting in gaps and moments of mind blanking,” Andrillon said. The research supports their hypothesis that mind blanking is the first step toward falling asleep, he said. It also fits with his own ongoing research that found mind blanking more than tripled among healthy volunteers who were sleep deprived for 24 hours. But the opposite can also be true: people who are very aroused, like after intense physical exercise, tend to report more blanking, suggesting that the phenomenon occurs “every time we go away from the sweet spot of optimal levels of arousal,” Andrillon said. The experience of mind blanking comes in varying degrees, from a complete gap to a sensation of feeling time passing, he said. From a practical perspective, asking people how frequently they experience the phenomenon could be a helpful way for doctors to judge people’s level of daytime attention and vigilance, he said. The review, “Where is my mind? A neurocognitive investigation of mind blanking,” is published this week in the Cell Press journal, Trends in Cognitive Sciences. National Post  

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