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Can a mouse be mindful? Researchers believe they have created the world’s first mouse model of meditation by using light to trigger brain activity similar to what meditation induces. The mice involved appeared less anxious, too.

Human experiments show that meditation reduces anxiety, lowers levels of stress hormones and improves attention and cognition. In one study of the effects of two to four weeks of meditation training, Michael Posner of the University of Oregon and colleagues discovered changes in the white matter in volunteers’ brains, related to the efficiency of communication between different brain regions. The changes, picked up in scans, were particularly noticeable between the anterior cingulate cortex (ACC) and other areas.

Since the ACC regulates activity in the amygdala, a region that controls fearful responses, Posner’s team concluded that the changes in white matter could be responsible for meditation’s effects on anxiety. The mystery was how meditation could alter the white matter in this way.


Posner’s team figured that it was related to changes in theta brainwaves, measured using electrodes on the scalp. Meditation increases theta wave activity, even when people are no longer meditating.

Read more: People who meditate are more aware of their unconscious brain

To test the theory, the team used optogenetics – they genetically engineered certain cells to be switched on by light. In this way, they were able to use pulses of light on mice to stimulate theta brainwave-like activity in the ACC.

Mice received 30 minutes of this stimulation for 20 days. Before and after the treatment, the mice underwent behavioural tests to measure anxiety. When placed in a box with a light area and a dark area, fearful mice spend more time in the dark.

The team found that mice that received theta wave stimulation were less anxious than mice given light pulses that induced other kinds of brainwaves, or who had no treatment at all.

Posner says this mirrors meditation’s ability to lower anxiety in humans and supports the involvement of theta waves in this effect. The team are still studying the white matter in the mouse brains and hope to report on any changes later.

Posner declined to speculate on whether the mice would have experienced mental states similar to mindfulness during the light stimulation, or whether it would replicate other effects of meditation training. “We don’t know how broadly it applies,” he says. “Maybe people will follow up other aspects of the meditation.”

Animal models have been helpful in understanding and developing treatments for anxiety, says Willem Kuyken, a clinical psychologist at the University of Oxford. He says that further investigation of how rhythmic brainwaves relate to anxiety could be worthwhile, but describing the mouse model as representing meditation is problematic.

“Meditation, to my mind, implies an intentional choice to deploy attention in a particular way, with qualities of curiosity, patience, equanimity and care,” he says. “Mice clearly are not able to meditate in this sense, but it will be interesting to see what facets of meditation can be examined and found to be common across animals and humans.”

Journal reference: PNAS, DOI: 10.1073/pnas.1700756114