This isn’t an entirely new idea. Beginning in the 1970s, researchers at the University of Michigan, led by Rachel and Stephen Kaplan, noticed that psychological distress was often related to mental fatigue. Modern life demands what the Kaplans call sustained directed attention on tasks both important and mundane—checking email, working a desk job, finding a parking spot. What leads to resting our brains’ directed-attention function? “Soft fascination,” explains Rachel Kaplan from her plant-filled university office. This is what happens when you watch a butterfly or the sunset or rain. You can’t help but stop multitasking or kvetching. That’s why Kaplan recommends a decidedly nonathletic approach to the outdoors, at least at times.

“When you’re pursuing a sport, you get cardiac points, but you’re not necessarily getting nature points,” she says. Research by her colleague Jason Duvall suggests that when you are distracted outside—running with an iPod, say—you may be more irritable and impatient later, less able to stay on task, focus, and plan than your nature-engaged peers.

Studies by the Kaplans and others show that after short walks in greenery, or even spells of looking at nature images in a lab, subjects’ directed-attention capabilities at least partly recover—people perform significantly better on cognitive tests and report feeling happier. They behave less selfishly when playing computer games. Turning down the front-brain disco ball also seems to improve creativity. And the more time in nature, the better. A recent pilot study by psychologists Paul and Ruth Ann Atchley of the University of Kansas and David Strayer of the University of Utah found that after three days of hiking and camping in the wilderness, participants in an Outward Bound course improved their scores on tests of creativity by 50 percent. “I’ll admit I’m a believer that there’s something profound going on,” says Strayer.

Yet, it’s been hard to see inside the brain to observe these processes at work. Neuroscientists want quantitative visuals. That’s starting to happen, mostly in labs in South Korea and the U.S. Studies have shown that when subjects look at pictures of nature, hemoglobin levels drop in the prefrontal cortex, meaning that the home base of executive function has switched a few lights off. (Similar effects have been seen in the brains of Tibetan monks, who appear to dim their brain wattage through meditation.)

Where’s the action going instead? To other parts of the brain, like the insula and the basal ganglia, says Kaplan protégé Marc Berman, now at the University of Toronto’s Rotman Research Institute. These are areas sometimes associated with emotion, pleasure, and empathy.

Berman has recently begun using functional MRI to watch people’s brains as they look at images of nature through virtual-reality glasses. “What we’re trying to find out is, what does a restored brain look like, and what does it look like as it’s getting restored?” says Berman. In the real world, filled with real nature, he would expect the effects to be even more pronounced. Miyazaki and Lee, with their hemoglobin-measuring spectrometer, intend to find out.

TWO WEEKS AFTER OUR experiments at Juniko and Hirosaki, Lee sent me preliminary results from my brain spectroscopy. Brightly colored squiggly lines on a graph show that my oxyhemoglobin concentrations indeed appeared lower in the forest than in the city. Lee said that results from me and the college boys would require more analysis, but for first-time field work he was optimistic. “I am very excited,” he said.

The results didn’t surprise me. My urban peregrination hadn’t been nearly as pleasant as the soft green trails of Juniko. Downtown Hirosaki is, like a lot of midsize cities, more functional than attractive. Walking on the hot asphalt, I passed four parking lots, two taxi stands, a bus station, and two loudly idling buses belching fumes. The results showed that my nervous system had responded. My systolic blood pressure had dropped six points after walking in the forest; obligingly, it went up six points after walking in the city.