Researchers discovered that mind wandering is linked to a specific brain activity pattern, sharp-wave ripples, similar to those observed during sleep.


Summary: Researchers from Osaka University found that mind wandering, especially when involving vivid and imaginative self-generated thoughts, is linked to a specific brain activity pattern known as sharp-wave ripples, which are typically seen during non-REM sleep and originate in the hippocampus. This study involved epilepsy patients with intracranial electrodes, revealing a connection between increased sharp-wave activity and less pleasurable, more imaginative thoughts. The findings, published in Nature Communications, suggest that understanding these brain states could have implications for conditions like autism, ADHD, and overall well-being.

Key Takeaways: 

  • Researchers from Osaka University found that mind wandering, especially involving vivid and imaginative thoughts, is associated with a specific brain activity pattern called sharp-wave ripples, commonly observed during non-REM sleep.
  • The study involved epilepsy patients with intracranial electrodes in the hippocampus, revealing a link between increased sharp-wave activity and less pleasurable, more imaginative thoughts.
  • Understanding these self-generated brain states could provide insights into various conditions, including autism, ADHD, and overall well-being, highlighting the potential for broader applications of the findings.

Researchers from Osaka University find that mind wandering, especially when associated with less pleasurable and more vivid and imaginative self-generated thoughts, is associated with a specific pattern of brain activity linked to memory and sleep.

When we think about things that aren’t actually happening, like when we daydream, the brain is essentially making up information rather than receiving and processing it—for this reason, researchers classify it as a “self-generated” brain state. 

Sharp-Wave Ripples and Memory

In a recent study published in Nature Communications, researchers from Japan identified that these self-generated states are associated with a specific pattern of brain activity known as “sharp-wave ripples,” which frequently occur during non-REM sleep. These ripples start in the hippocampus, a brain region that is essential for making and retrieving memories.

To study the relationship between these sharp-wave ripples and different kinds of thoughts, the research team made use of the information that’s collected when patients with drug-resistant epilepsy are about to undergo surgery (to remove the starting point of the epileptic activity in the brain). 

An epilepsy patient with intracranial electrodes implanted in the hippocampus answering questions about the content of the patient’s thoughts while measuring electroencephalography. Photo credit: Osaka University

Intracranial electrodes are implanted in the hippocampus in these patients, and the activity in the brain is continuously tracked so that the surgeons can identify the epileptic region and be sure that they aren’t removing a part of the brain that will have unexpected consequences.

Study Methodology and Findings

“We asked patients undergoing this electroencephalographic brain monitoring for 10 days to complete an hourly questionnaire relating to their thoughts and emotions,” says lead author of the study Takamitsu Iwata in a release. “We mainly wanted to see if we could identify any links between the recorded brain activity and how the patients were feeling and thinking at the time.”

In general, the sharp-wave ripples from the hippocampus were generated in patients at night (presumably during sleep). Furthermore, the research team noticed a link between increased sharp-wave activity and thoughts that were more vivid or imaginative and less desirable or task-related, ie, when their minds wandered.

Implications for Broader Populations

“Notably, although our study was conducted entirely on people with epilepsy, we did our best to remove epilepsy-related data so that the results are applicable to healthy populations,” says Takufumi Yanagisawa, MD, PhD, senior author of the study, in a release. “The similarities between many of our results and those of previous studies, using other species or methods, indicate that our approach worked well.”

There is increasing evidence that self-generated brain states, including mind wandering and intrusive thoughts, have complex links with intelligence, autism, attention deficit disorder, and happiness/well-being. A better understanding of the brain regions and activity that cause these states may therefore help people with a range of different conditions.

Photo 198248110 © Prostockstudio | Dreamstime.com