Mice do not, so far as we know, practice meditation. But in order to study how that activity affects human brains at the cellular level, researchers at the University of Oregon managed to put murine brains into a somewhat equivalent state. Their experiments, reported in March in the Proceedings of the National Academy of Sciences, suggest new ways of investigating how a person’s brain can constantly reshape itself.
Past studies have suggested that people who meditate tend to have more white matter in and around the anterior cingulate cortex, a part of the brain involved in regulating emotions. Meditation also seems to intensify theta-wave activity, a type of rhythmic electrical pulsation often associated with a state of calm. Psychologists at Oregon speculated that the surge in theta waves stimulated the production of cells in the white matter. But they needed to develop an animal model of this activity; they obviously couldn’t examine the living brain tissue in meditating humans.
So the psychologists asked colleagues in the university’s neuroscience department if they could increase theta-wave activity in mice, which were already being used to study brain states and neural plasticity, or the brain’s ability to rewire itself. Could the neuroscientists create a comparable effect in mice?
Yes, it turned out, using a brain-research technique known as optogenetics, which uses light to turn on and off neurons, and mice that have been bred with specific genes responsive to light. The Oregon group, by pulsing the light at the same frequency found in human theta waves (eight hertz), were able to switch on the neurons in the anterior cingulate cortexes of the mice. They also exposed some mice to light at higher and lower frequencies and left others alone.
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