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- Annapurna Base Camp: A High Altitude Brain Study
Annapurna Base Camp: A High Altitude Brain Study
— Annapurna Base Camp —
Studying the Brain at High Altitude
This two week expedition aimed to establish a method of measuring and characterizing task-related neuronal activity that might be relevant to altitude-induced neurological dysfunction and ground-based neurological disease. Our trek ascended to 4,130 meters to Annapurna Base Camp, home to the tenth highest and most deadly mountain in the world. This project was generously funded by the Harvard Travellers Club with equipment sponsorships from Brain Vision LLC & J+S Vision.
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Read our Letter to the Editor in the Journal of High Altitude Medicine & Biology
Read the Brain Products Press Release
Early this year I received a notification that the Harvard Travellers Club was going to support my proposal to study the brain during a trek in the Himalaya. There’s some reason to believe the effects of altitude mirror what is happening in those with chronic movement disorders, like Parkinson’s disease. My hypothesis is that normal people in extreme environments look like diseased people in normal environments. If this is true we could apply ground based therapies to aid mountaineers and use altitude as a reversible model to study disease. This was my journey to develop a way to test that, half a world away. We woke up in Tikhedhungga.
Jenna is a molecular biologist. This morning wasn’t about science though, as we played balloon bop and makeup artist with this wonderful Nepalese girl. She insisted that even I get some lipstick over breakfast. We were all fabulously trail ready.
As we were leaving, she ran up and grabbed Jenna’s hand, pulled her back into the tea house and over to the nearest guest room. She didn’t speak English, nor did we speak Nepali, but it was clear we weren’t supposed to leave yet. It was a trick. The sweetest one of all. She mirrored our tongue one our way out… “Bye bye! Nice to meet you!”
The climb today is 1540 meters; almost six hours rocky steps upwards. The Himalayan countryside is wonderful. The trail turns from valley to lush forest and back. These mountains were formed by the collision of the Indian and Eurasian plates 50 million years ago. The grounds of sedimentary and metamorphic stones form the trails, rich in quartz, giving the dust a golden sparkle in the sun.
To work at Ghorepani. We monitor heart rate, blood oxygen, and take a questionnaire for altitude sickness everyday. The uninsulated wires and walls within the villages make recording small brain signals there impossible. It’s like trying to pick up a whisper with a freight train next to you. So much for any control over the environment. When light falls below the valley rift the temperature pulls on foggy sweater strings, unraveling a chill onto tasking finger tips.
An hour skywards landed boots at Poon Hill, a panoramic glimpse of the southeastern Himalaya. Dhaulagiri is the most prominent from this view with one of the largest mountain faces on the planet. Over it’s 8,167 metre peak is the Tibetan Plateau—the Roof of the World—a sweeping flat land mass the size of Alaska and Texas combined.
Sun breaks over the eastern edge of the Annapurna Massif lighting the high grasslands to a golden blaze. Pilgrims forge towards the hilltop in short, broken steps over broken shale.
We decide to leave our imprint by constructing a stone cairn above all the rest on this small monument ledge. Stacking rocks is an ancient human practice, often marking burial or ceremonial sites. Here we stack them for good luck, homage to the Mountain Spirit, but it’s thought that they may also have been used for keeping the dead from rising when atop a relic stupa.
Water fell from the Rhododendron Forest. Through the Deurali Pass the hills teetered and toyed with 3,000 metres. The approach to Ben Thanti weaved against high slate with a quick stream echoing rosey sandstone and goldleaf.
A corner revealed a quarried infinity of cairns (pronounced \ˈkern\). It must be one of the largest collections in the world, spanning as far as eyes could see. Each stack with an identity; some with writing, some flowers, some with small sticks patterned at the base. Why the human spirit is magnetized, why it manifests in these adornments is a wonderful mystery. Here, perhaps it’s our wanting to build, and construct, to achieve new heights, to observe the endurance of our delible doings.
Tadapani was covered in a cloud when we arrived yesterday. The mountains were a morning surprise. To the left is Machhapuchhre, otherwise known as “Fish Tail”, just a few metres short of 7,000. It is revered as a sacred peak, therefore no human has set foot on its summit.
Coming up the ravine we found a man hunched on a rock holding his water boot in painache. I put my index finger tips together and motioned a break and he shook his head with an agonizing confirmation. A compound fracture, I thought. I took off his boot to only find a small gash. He was able to explain that he had hit a stone step with his shin. We cleaned up the wound, gave him a few days worth of gauze and ointment, and some fresh water. He kissed Jenna’s hand about forty times, making me wonder if the whole thing wasn’t a pretty-lady ploy.
A net descent to Sinuwa, the first camp on the direct path to Annapurna Base Camp. Gray langurs, a type of Old World monkey, were perched in the forest trees; outlined by their silver coats, hidden behind their charcoal faces. Still valleyed, we have cold mornings, hot middays, and cold evenings. That meridian star.
It’s all fun and games until a herd of goats nearly tramples your gear. From the top of the hill the landowner began throwing sticks and stones at them as they infringed on her garden. Jenna quickly became goatherd, hustling them back down the hill. Add to methods section: Check for goats before beginning experiment.
This morning we were passed by two girls running down the trail on their way to school. I decided to follow their steps; they knew the jogs and small shortcuts that hopscotched around slow movers. The girl directly in front of me was carrying a large bag of rice, about the size of her torso. At the bridge I greeted her—Namaste!—and motioned that I could carry the rice for her. She handed it to me and took off behind her friend over this river pass. At the other end she met her mother, delivered the rice, smiled at me and continued ahead of us towards her day.
Her face, all the faces, vibrantly aged. It is the sun. Or labor. The mountains. An observance of impermanence, of The Way. So far from those hollowing things. Broken in. Unbroken.
He companioned us for about a mile with a travellers indifference. At a turn ahead he darted into the forest and then… BANG! SHREEK! The dog jumped out from the brush, chased by a gang of macaques. It appeared to be a war over a carcass in the woods. The dog followed us into the next village, seemingly to gather his larger mountain mutt friend, them both booking back behind us towards the monkey business. We laughed, and named the trail dog, America. That playful explorer. That troublemaker.
By 16:00 the mist engulfed our valley backdrop. We are back at 3,000 metres and for the first time show a dip in our SpO2 readings; 92% and 94%. These are crude measures that we can use to assess health and safety. We hope that our research here will begin to characterize the neuronal adaptations that occur at high altitude. The brain is a fantastic liar and can cover up problems until they reach a critical level. Consider that 70-80% of the dopamine cells are dead by the time most motor symptoms arise in Parkinson’s disease; a disease defined by dopaminergic cell loss. We need better biomarkers—early detection systems—both in the mountains and on ground.
Annapurna Base Camp. Surrounded in all directions by the Annapurna Massif, a range that includes nine major peaks over 7,000 metres. Annapurna I is the tenth highest mountain on planet Earth, and statistically the most dangerous to climb. We will stay planted at 4,130 metres for our experiment, the highest altitude planned for our expedition.
Pictured ahead is Annapurna South, the 101st highest mountain in the world. This place holds an obvious sentiment. Prayer flags fly, cracking in the wind. They are the colors of our elements; of sky, air, fire, water, and earth.
New highs are new lows: 91% SpO2. No signs of altitude sickness for either of us. Fitness has nothing to do with it, some people just get hit harder. In fact, older people tend to cope with altitude better than young, for some reason. That we both feel normal means that any adaptations we find in our brain activity precedes our awareness. We track hand movement in this skilled reaching task using an accelerometer. Paired with the other behavioral sensors, we will have a clear view of how performance is changing, if at all.
The most connected to ground I’ve felt in some time. The clouds roll into the valley ahead but don’t endure the last steps upwards, antagonized by the windchill. The moonrise illuminates this panoramic gorge. We share stillness in the rasping mantras of prayer flags behind.
Clothes lift off the line frozen solid. Cold toes last night. Today is a 1,210 metre descent to Bamboo. We catch light briefly at Base Camp but soon sink into a shadow, hugging the valley downwards.
For a kilometer we enjoy a meadow trail along the Modi Khola River, the major drain of the East Annapurna Glacier. Rounding Hinku Cave, the sister peaks of Gandharwa Chuli and Machhapuchhre streak a morning sun.
Bamboo village is a jungle of power lines. We have to again venture far into the forest to find reprieve from what is precisely a 52.5 Hz buzz, since I’m not keen on notch filtering the entire dataset. We integrate an “imagined” trial once every minute into our reaching task. This might offer the ability to assess if changes in brain activity are preferentially associated with movement itself or simply movement preparation.
A single village. A rising moon. A lanterned dream. That dithered candlelight which made us once believe our freckled heaven is one sharp breath; from fire to wick.
I almost stole this baby goat. Walking into Ghorepani we saw an entire flock of them being tamed by a small boy. We ran down the rock steps like little kids towards him—Namaste! Then I pantomimed picking one up. The boy nodded.
It’s the last day of trekking between tea houses. The seventh consecutive day of recording brain activity. Descending to Jhinu Danda, at 1,780 metres, is new turf, a more direct route to Nayapul. Today there’s no sacred mantra for the six hour journey; it’s “hot springs”, as they are apparently a spectacular treat awaiting.
The hot springs filled three pools that overlooked rushing cascades of the Manjh Danua. It was decided: this would be a horrible introduction to the mountains. Not until feet are battered and foreheads sunscorned. It was a short moment to enjoy nature, the expedition, the mission.
When I saw that we were heading to Newbridge I thought the bridge might be a little newer than this. Stopping in the center, I’m five years old, spitting into the void and counting the seconds until it smashes into the rocks below.
We covered thirteen kilometres to the southwest while descending nearly a thousand into Birethanti. We had two pieces of toast in the morning with some jam, the fuel for that sunridden six hour journey. Arriving, we bought a small bunch of bananas, traded boots for sandals, and chartered a cab. The mountains left through those crooked dirt roads of Jhobang and Naudanda.
The day rests in Pokhara along the eastern edge of Phewa Lake. Annapurna South is visible just over the hills of Methlang. Here we meet an Indian family and make quick friends with Yash, Vaibhav, and Shweta. By flight or bus, we take back to Kathmandu in the morning.
At the edge of the Bishnumati River we enter a small Buddhist temple off Thapkia route. It’s easy to be respectful but hard to not feel out of place. I make an offering to the Stupa, an observance of the Three Jewels (or Refuges). I spent six months this year living in a Buddhist temple, each morning began with a chant of the Three Refuges in Sino-Korean. These are the Buddha, the Dharma, and the Sangha; the cornerstones of all Buddhist forms; our own Buddha nature, the ultimate Truth and Middle Way, and our community. For my offering I was pointed towards a plate of red vermillion paste and proceeded to apply a small dash of it onto my Third eye—between each eyebrow—a mark known as a tilak (pronounced /ˈtilæk/). Of its many meanings, one is to serve as an auspicious mark of a great journey or campaign.
Swayambhunath is one of the most sacred Buddhist pilgrimage sites in the world. It sits central to, yet high above Kathmandu Valley. Also known as the Monkey Temple, wild macaques roam the temple grounds as holy figures, the result of endemic Buddhist mythology. This temple was wracked by the 2015 earthquakes in Nepal and the rebuild was active during our visit. The patrons both high in this temple, and of the ground, are still devastated by the natural disaster. They are also disturbed by how much history was shaken to the ground, but tell heartbreaking, personal stories of their families and livelihood being displaced from underneath.
Nature’s first green is gold, Her hardest hue to hold. Her early leaf’s a flower; But only so an hour. Then leaf subsides to leaf. So Eden sank to grief, So dawn goes down to day. Nothing gold can stay. —Frost
The flags were being hung, dancing in the wind, as we circumambulated the stupa. Prayer wheels lined the perimeter in hypnotic ad infinitum. The Sanskrit mantra, Om mani padme hum, appears on each in rich copper polished by the fingers of those who spin them. Each syllable of the mantra corresponds to a sacred realm of existence, and each realm is associated with a color, now flying overhead.
Leaving the temple there are curious eyes. Of theirs, of mine. I don’t resist the urge to observe, here on the border of cement stairs and a flourishing hilltop forest. In Tibetan, the temple name translates to, “Sublime Trees”. Soon, I’m too close to baby monkey, and our curious kinship is broken by the mother, who is not as privy to my presence.
Kathmandu has a small population of roaming Sadhus; religious ascetic yogis adorned in vibrant saffron-colored clothing and paints. I greet him with a bow. He answers my questions, in all their naïveté, about his garb and implements. He was a fresh breath in the dusty streets of Nepal.
From the air Nepal remains lined by prayer flags atop small village homes and coursing down disparate rounded temple stupas. I can see the long, serpentine road that connects Kathmandu to Pokhara. Those famous gateways to the Himalaya; those places where modest dreams meet the floor and ceiling of the Earth.
Many stories brought home and many left for another day. While publishing this travelogue I’ve been analyzing the data we recorded. Our findings show distinct adaptations in motor-related brain circuitry that correlate with altitude. These changes are similar to those we see emerge in Parkinson’s disease, which are often directly associated with slowness or absence of movement. Although we suffered no deficits in task performance, our data illuminate a link between motor deterioration at high altitude and a chronic movement disorder at sea level. I’m excited to be presenting these findings in full at the 2017 International Hypoxia Symposia in February.
ENHANCED NEURONAL SYNCHRONY DURING SKILLED REACHING AT HIGH ALTITUDE
Matt Gaidica1 and Jenna Clem2
1Neuroscience Graduate Program
2Department of Molecular, Cellular and Developmental Biology
University of Michigan, Ann Arbor, USA
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Methods: We implemented cortical electroencephalography (EEG) on two healthy, right-handed subjects during a self-paced skilled reaching task over a seven-day ascent to Annapurna Base Camp in the north-central region of Nepal.
Results: We correlated task-centered sensorimotor oscillatory activity of five physiologically relevant EEG bands (Delta: 0.5-3.5 Hz; Theta: 4-8 Hz; Alpha: 7.5-12.5 Hz; Beta: 13-30 Hz; Gamma: 30-100 Hz) with daily measures of altitude, ascent, and blood oxygen saturation (SpO2). Our data reveal a significant positive correlation between sensorimotor delta phase-amplitude synchrony and altitude.
Conclusions: Our method represents a novel approach to studying the brain at high altitude and revealed task-related neuronal adaptations. Although we experienced significant changes in SpO2 at altitude, our task performance remained unchanged. This suggests that the enhanced delta phase and amplitude characteristics of our EEG activity at high altitude likely represent the recruitment of additional sensorimotor resources to maintain task coordination. We hypothesize that the homeostatic delta oscillations represent a separate oscillatory system that is driving task-related, cortical-level compensation. While healthy individuals may have relatively robust compensation machinery, it may breakdown in subjects with disease, under abnormal stress, or generally in situations where basic brain functions serving survival are paramount. Therefore, potential countermeasures for high altitude mountaineers may benefit from a dual approach: one for supplementing homeostatic processes and another that enhances cortical-specific pacemaker networks.
Acknowledgements: The Harvard Travellers Club financially supported this study. Brain Products, LLC, sponsored all equipment. This study received “non-regulated” status by the University of Michigan Medical School Institutional Review Board (ID: HUM00119637).