The Great (Brain) Space Race
“The Dish,” a 150-foot wide radio telescope that does call-and-response conversations with satellites and spacecraft overhead, sits among postcard-pristine Californian hills near Stanford University. Parents with strollers, retiree birdwatchers and speed-walking confidantes fill the hills’ paved trail system in daylight hours. A few years back, unbeknownst to anyone save a team of Stanford researchers that recruited a group of study participants that agreed to have their brains scanned before and after they hiked the area, the Dish became a neuroscience laboratory — of a dusty, oak-scattered, sun-dappled sort.
These nineteen volunteer hikers, who took to the trail on separate days and in solitude, got a better shake than the group of volunteers acting as their comparators, who were relegated to walking the same amount of time on a nearby commercial street, abutting an abrasive stream of multi-lane traffic. This urban stroll acted as the experiment’s control condition, setting up a head-to-head comparison to help isolate the mental benefits and brain changes that occur with a dose of nature.
The presence of this nature-meets-neuroscience fieldwork against the backdrop of the Dish, a waning piece of Space Age infrastructure christened in 1961, just four years after Sputnik and five years before the Apollo 11 moon landing, is a reminder of a different kind of space race now underway. Humanity’s galactic ambitions can be turned inwards without losing any sense of immensity, imputed to the immeasurable dimensions of the human mind and its hallowed 3-pound counterpart, the brain. Where once rockets and radio telescopes aimed skyward spoke of American progress and possibility, neuroscience now also captures headlines and government investment, framing neuroscientists as pioneers of inner space, using brain scanners and stimulators aimed headwards to measure and manipulate brain activity underneath.
This brain space race plants proverbial flags in the grey-and-white-matter floating in our skull, laying claim to new pictures and possible therapies for our most human yet inscrutable Earthly inheritance. Gone is the Soviet-American astronautical contest (Will capitalism or communism win the heavens?), but questions about private enterprise versus shared ownership still remains. Of the countless ways to change the brain (for better or worse), there are two very different ways of therapeutically changing the brain that have been studied— time in nature and brain stimulation devices — which have each landed on the same promising region of brain known as the subgenual cingulate cortex. They provide a helpful allegory to understand this neuroscience-centric age of addressing mental health and well-being. The question is: will low-tech, communal resources like parks, community gardens and other nature spaces be given a neuroscience nod of legitimacy that helps protect and prioritize them as mental health resources, or will high-tech, private solutions for mental health continue to be seen as the leading edge of psychiatry?
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The brain’s subgenual cingulate sits two inches behind your eyes, like the front bumper of a sedan-shaped strip of brain tissue known as the cingulate cortex. It’s been described as “the neural interface between emotion, sensation and action.” In the early 1900s, the German neurologist Korbinian Brodmann created a system for classifying areas of the brain according to anatomical and cellular characteristics. He named the subgenual cingulate “Area 25”. Brodmann correctly postulated the function of several areas of the brain. In the case of the subgenual cingulate — which amounts to about a teaspoon of brain tissue — evidence for its role as a neural interface, crucial in creating poetic mood states like sadness or running amok in disorders like depression, would come nearly a century later.
With the advent of brain imaging, it’s now known that a decrease in subgenual activity (Cg25 for short) occurs with many forms of antidepressant treatment, including medications, electroconvulsive therapy (ECT), and ablative surgery (disabling a part of the brain surgically). Its overactivity in depressed patients, measured by its metabolic rate during a positron emission tomography (PET) brain scan, can predict a poor response to subsequent antidepressant medications and cognitive-behavioral talk therapy. If symptoms fail to respond to several trials of these psychiatric standbys, patients are deemed to have “treatment-resistant” depression.
To help patients in this category, a team of scientists and neurosurgeons went straight for the source. Using a technique called Deep Brain Stimulation (DBS), they implanted a wire electrode directly into the Cg25 of six patients and began delivering electric current to the area, effectively relieving the depression of four of the patients by decreasing its activity. Though quelling the restless masses of Cg25 neurons seems to play a role in the efficacy of many different forms of mental health treatment, the image of an electrode staked into brain is certainly striking for our visually-driven species: the researchers, like an neuroanatomical Apollo 11 team, made direct contact with the lunar-hued grey matter of Cg25, claiming it for the brain stimulation bloc.
The connections between nature immersion and the brain are less concrete but can nevertheless lead to some heady implications. The aforementioned Stanford Dish experiment, published in 2015 and led by Dr. Greg Bratman (now at the University of Washington), caused a stir as the first neuroimaging study to directly investigate the effect of nature exposure. Bratman and colleagues found that the people in their study who walked the Dish area’s bucolic landscape, as opposed to those who navigated the busy, commercial thoroughfare, were less likely to later report being caught up in a negatively-tinged, self-focused thought process (known as rumination). The clincher was that these subjective reports came with objective evidence of a reduction in brain activity in Cg25, suggesting that countryside can act as a brain-changing technology. The inverse was also true: brain-changing potential could now be pinned to the geographic map.
The small study has yet to be replicated, and its media splash and popularity within environmental circles certainly outstripped its preliminary conclusions. Yet it presents a tantalizing future. If brain maps and land maps overlap, if we can study our natural expanses not just as places outside our bodies but as corresponding neural properties inscribed within them, then the science and protection of healthy brains and unspoiled environments may overlap as well.
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The Americans and Russians knew they were in a race for the moon, and that this symbolized far more than their respective aerospace abilities. Neuroscience is different, more like modern satellite operations, with thousands of research teams in orbit around the human brain, training their instruments on different aspects of its functioning. DBS is focused squarely on psychiatric patients with the most treatment-resistant disease, whereas a dose of green space, even if it becomes a carefully rationed medicine in some climate-dystopian future, is generally thought to be good for everyone. Yet the increasingly crowded field of mental health innovation may put seemingly disparate treatments on a collision course, especially as mounting climate and ecological crises sensitize certain segments of the public to reconsider what The End of Nature (the title of Bill McKibben’s breakout book on global warming for a general audience) might mean for our mental well-being.
A noninvasive brain stimulation technique now gaining prominence — Transcranial Magnetic Stimulation (TMS) — uses a wand about the size of ping-pong racket to send magnetic pulses through a patient’s scalp. TMS can activate or inhibit parts of their brain, especially the neocortex closest to the scalp, all while they sit calmly in what looks eerily like a dentist’s chair. Like DBS, but at a fraction of the cost and with much lower risks than sticking electrodes into the brain, TMS has shown success in treatment-resistant depression. Again, this success has been traced back to decreased Cg25 activity.
TMS takes time, money and infrastructure. Although researchers are looking into more efficient ways of delivering the stimulation, it can require a patient to go to a TMS clinic 5 days a week for 20–40 minute-long sessions for up to 6 weeks. The money needed to promote and finance the research and expansion of TMS fits squarely into our current health care model: academic researchers can apply to government-funded agencies like the National Institutes of Health (NIH) to do clinical trials of TMS, then partner with private industry to develop and bring their discoveries to market in the form of new TMS devices, techniques or treatments. This all feels very scientifically rigorous and apolitical at first glance. Nature therapy isn’t bringing anything new to market; in fact, in terms of leaving enough space open and undeveloped to enjoy, the future of nature therapy may rely on government protections against the market forces that inexorably churn lands into strip mines, strip malls or luxury condos — a political act indeed. There are a few businesses that could stand to benefit from a biomedical emphasis on expanded access to nature; REI, the outdoor clothing and gear company, has partnered with UC Berkeley and the Sierra Club to form the Great Outdoors Lab to promote research on the benefits of getting outdoors. But a tried-and-true business model for integrating environmental protection into neuroscience and brain health does not exist.
Despite these differences between TMS and time in nature, one can wonder what dedicating the same time spent in the TMS chair to some green activity, like going to your local park or community garden, might yield. Nature “dosing” studies, where large cohorts of people are tracked in terms of outdoor activities and health metrics, are appearing with increasing frequency, highlighting the health benefits of such things as a minimum effective dose of nature (30 minutes per week according to one study) or its peak effect (benefits begin to plateau after 2 hours per week, according to another). A recent study from researchers at the University of Pennsylvania School of Medicine was designed like a drug trial, randomly assigning certain vacant lots around Philadelphia to be transformed into community gardens, while others remained untouched. By controlling the dose, the project spoke in biomedical terms, demonstrating that urban green space renewal can reduce general distress and symptoms of depression for people who live nearby. The effect was especially pronounced in low-income neighborhoods.
The idea of nature conservation and restoration as mental health care is, tellingly, more unconventional than are brain implants and stimulators. Analogy to NASA programs may convey the scientific significance of white-coat “moonshot” projects like BRAIN (the NIH’s multi-billion dollar Brain Research through Advancing Innovative Neurotechnologies initiative), which wants to create a complete, detailed map of its eponymous organ. But nature therapy research, whether it rides the neuro-centric coattails of endeavors like BRAIN or finds legitimacy in ecological or even moral frames of reference, will demand the powers of less glamorous government agencies like local planning and zoning commissions or the Department of the Interior (DOI). (Tasked with protecting our public lands, national parks and wildlife refuges, the DOI is now doing quite the opposite under Trump appointees like Ryan Zinke and David Bernhardt.) Neuroscience alone is unlikely to inspire pitchfork rebellions to defend our countryside and community gardens. Similarly, with the average kid spending half as much time playing outside as their parents did, and the average American spending nearly 93% of their lifetime indoors or in a car, a fellow feeling for nature will not provide most people the grounds for embracing a Green New Deal or the resurgence of federal environmental protections. (The Clean Water and Air Acts are now half-a-century old and were last amended during the Reagan and George H.W. Bush presidencies, respectively). But acknowledging and emphasizing high-quality nature experiences as both a public good and a psychiatric resource could add brain health to the long list of reasons to protect the natural world from extraction, overdevelopment and climate disruption.
What will this mean for the public’s long-standing fascination with the mind and brain? Space walks and moon landings may become less apt metaphors than nature walks and a return to Earth— both its stimulating beauty and basic inhabitability.