The Psych Files

Tag: neurotransmitters

  • Why People Step Out of the Plane — and Go Back Up the Next Day

    Why People Step Out of the Plane — and Go Back Up the Next Day

    Picture standing in the open door of a plane, wind roaring, the ground a long way down. Almost every part of you is shouting one thing: do not do this. Some people hear that voice, nod, and jump anyway. And here’s the part that really gets me — after a terrible accident, some of them go back up the very next day. Why?

    That question came roaring back for me after a recent New York Times feature by Kurt Streeter and Nicholas Bogel-Burroughs, which opened on a single brutal weekend: a skydiving plane crash in Missouri, a fatal BASE jump near Moab, and a rope jump in Brazil where the crew forgot to clip the harness. Strip away the details and the victims all faced the same thing — a brain built to keep them safe, screaming the obvious — and each went anyway.

    I’ve actually talked about the people who do this kind of thing before. A while back I interviewed Dr. Kenneth Carter, a psychology professor at the Oxford College of Emory University and the author of the book Buzz: Inside the Minds of Thrill-Seekers, Daredevils, and Adrenaline Junkies. He studies exactly this — and the same New York Times piece quotes him too.

    The first thing Carter told me is that “adrenaline junkie” mostly gets it wrong. The trait at the center of this is sensation seeking — the pull toward novel, varied, and intense experiences, and a willingness to take risks to get them. It traces back to Marvin Zuckerman, who discovered it almost by accident while running sensory-deprivation studies. Some people sat for hours in a quiet, blank room and felt fine; others couldn’t last minutes. No test at the time could predict who was who, so Zuckerman built one.

    Here’s the piece most people miss: high sensation seekers don’t feel the same panic you and I would. Carter’s work shows they tend to run on a different chemistry — less cortisol, the stress hormone, and more dopamine, the brain’s reward and motivation signal. So the moment that would flood you with dread becomes, for them, a moment of clarity. Time stretches, the noise drops away, and they describe picking out every crack in the rock as they fall past.

    Zuckerman’s scale breaks the trait into four parts, and I think this is the most useful way to understand it. The first two tell you what kind of seeker someone is: thrill and adventure seeking (the skydiving, the wingsuits) and experience seeking (fearless eating, far-flung travel, even striking up debates with strangers). The last two tell you how much trouble they might find: disinhibition, the tendency to leap before looking, and boredom susceptibility, how badly they need stimulation. As Carter put it to me, the danger usually isn’t the activity itself — it’s doing it impulsively. “It’s good to look before you leap,” he said, “if you’re leaping off a bridge.”

    A couple of things surprised me. Sensation seeking lines up with openness — the Big Five trait about curiosity and appetite for the new — but it is not the same as extraversion. Plenty of high seekers are quiet introverts. And I’ll admit I have skin in this game: I took Carter’s scale and scored a 13, which is low (he scored even lower, an 8). The few points I earned all came from experience seeking — I like exploring strange places. I’m also someone who gets a real jolt of nerves before stepping on stage for community theater, then loves it. Not the same as jumping off a cliff, but maybe a cousin of it.

    So what do you do with this? Two things. If you love someone who’s wired this way, understanding the trait helps — it isn’t recklessness for its own sake, and a calmer partner often becomes the “anchor” who keeps the risk in check. And if you’re the seeker, Carter’s warning is the practical gold: the trait isn’t the problem, impulsivity is. Build in the pause. Look before you leap.

    If you’re studying psychology, scroll down — I’ve pulled out the key concepts this research illustrates, in plain language you can use for an exam.

    Psychology Terms in This Article

    Sensation seeking — A personality trait describing how strongly someone is drawn to novel, varied, and intense experiences, and how much risk they’ll accept to have them. Zuckerman’s scale runs from about 8 to 40, with most people near 25; the extreme athletes in Carter’s work often score in the high 30s, which is why the same jump reads as terror to one person and joy to another.

    Dopamine — A neurotransmitter tied to reward, motivation, and the anticipation of something good. High sensation seekers appear to get a bigger dopamine payoff (with less of the stress hormone cortisol) from risky, novel situations, which helps explain why danger can feel energizing rather than frightening to them.

    Openness — One of the Big Five personality traits, marked by curiosity, imagination, and willingness to try new things. Sensation seeking correlates with openness, which is why the experience-seeking side of the trait shows up in adventurous eaters and travelers, not just cliff jumpers.

    Extraversion — The Big Five trait covering sociability and seeking stimulation from other people. The surprising research point is that sensation seeking is not reliably linked to extraversion — many high seekers are introverts — so the two traits should not be confused on an exam.

    Trait theory — The approach to personality that explains behavior through stable characteristics that show up across situations and over time. Sensation seeking is a textbook example: it’s measurable, fairly consistent within a person, and even shifts predictably with age, peaking in adolescence and easing as we get older.

    Yerkes-Dodson law — The principle that performance improves as arousal rises, but only up to a point, after which it drops — an inverted-U, with the ideal level differing by person and task. It offers a neat way to picture sensation seekers: they may need a much higher level of arousal to hit their personal sweet spot than the rest of us do.

    References

  • Your Muscles Are Talking to Your Brain — and It Might Be Why Exercise Fights Depression

    Your Muscles Are Talking to Your Brain — and It Might Be Why Exercise Fights Depression

    You already know what people tell you when you say you’re feeling low: go for a walk, get some exercise, you’ll feel better. And maybe part of you bristles at that, because it sounds too simple to be real. How is moving your legs supposed to touch something as heavy as depression? Well, scientists have just traced the actual messenger that carries the news from your muscles up to your brain — and it turns out the advice has a real chemical backbone.

    The study appeared in Molecular Psychiatry and was led by Suk-Yu Yau, an associate professor in the Department of Rehabilitation Sciences at Hong Kong Polytechnic University, working with a team across several institutions. They zeroed in on a protein called apelin. When you work your muscles, they don’t just burn calories — they release proteins into the bloodstream that act like messengers to the rest of the body. Apelin is one of those messengers, and your muscles pump out more of it when you push them.

    Here’s what the team did. They took mice and put them through a few weeks of mild, unpredictable stress until the animals showed the rodent version of major depressive disorder — the persistent low mood and loss of interest in pleasure that defines the condition in people. The stressed mice stopped preferring sugar water, groomed themselves less, and gave up faster in a swim test. Then some of them got a running wheel. After four weeks of voluntary running, the exercising mice bounced back on all three measures, and their blood and brains were noticeably richer in apelin. The biggest source? The calf and shin muscles of the hind legs.

    Then came the clever part. The researchers bred mice whose muscles couldn’t make apelin at all. Those mice ran just as much — and got nothing for it. No mood improvement, and no growth of new brain cells. Flip it around: when they used a virus to force ordinary muscles to crank out apelin without any running, those couch-potato mice improved just like the runners did. That’s about as close as biology gets to saying “this one molecule is doing the work.”

    So how does a muscle protein lift your mood? The apelin crossed the blood-brain barrier and reached the hippocampus — a structure deep in the brain that’s central to memory and mood regulation. Once there, it triggered neurogenesis, the birth of brand-new neurons, which the depressed non-runners never got. It also strengthened the connections between existing neurons by boosting their glutamate signaling, the kind of synaptic strengthening researchers call long-term potentiation — the same cellular process behind learning and memory. In other words, exercise wasn’t just making the mice feel better in some vague way. It was physically rebuilding the brain’s wiring, a clear demonstration of plasticity, the brain’s lifelong ability to reshape itself in response to what the body is doing.

    I spent years as a college professor telling students that exercise helps with mood, and honestly, I always felt a little hand-wavy saying it — like I was repeating folk wisdom. Reading this, I finally have the mechanism I wished I’d had back then. It’s a small thing, but it’s satisfying to see a piece of everyday advice turn out to have real machinery underneath it.

    What can you do with this? The finding points to something specific: leg-driven movement seems to matter, since the hind-leg muscles were the main apelin factories. Walking, cycling, stair climbing, squats — the stuff that loads your lower body — looks especially worth keeping in your week. And the researchers stress that holding onto muscle strength as you age may help protect your mood, not just your mobility. You don’t have to run a marathon. You just have to keep your muscles in the conversation.

    One honest caveat: this was done in male mice. The authors are upfront that female, older, and human studies still need to happen before anyone promises results, partly because hormones and muscle mass differ by sex and could change how much apelin the body makes.

    If you’re studying psychology, scroll down — I’ve pulled out the key concepts this research illustrates, with a plain-language definition and a note on how the study demonstrates each one.

    Psychology Terms in This Article

    Major depressive disorder — A mood disorder marked by persistent sadness, hopelessness, and a loss of interest in activities that used to feel rewarding. The researchers induced a rodent model of it through chronic mild stress, then measured it through reduced interest in sugar water (a stand-in for the loss of pleasure called anhedonia) and faster giving-up in a swim test.

    Hippocampus — A structure in the brain’s limbic system that’s essential for forming new memories and helps regulate mood. In this study, the muscle-made apelin traveled all the way to the hippocampus, and that’s where it produced its antidepressant effects — a reminder that this region isn’t just about memory.

    Neurogenesis — The formation of brand-new neurons, which we now know continues in certain brain regions throughout adult life. Exercising mice grew new hippocampal neurons while the non-exercising depressed mice did not, and mice without muscle apelin showed no new growth even when they ran.

    Long-term potentiation (LTP) — A lasting strengthening of the connection between neurons based on recent activity, considered a core cellular mechanism of learning and memory. Apelin enhanced glutamate signaling and the function of NMDA receptors in the hippocampus, strengthening neural connections in exactly the way LTP describes.

    Plasticity — The brain’s capacity to change and reorganize itself in response to experience throughout life. This whole study is a case study in plasticity: a behavior (exercise) sent a chemical signal that physically remodeled brain tissue and shifted mood.

    References

    Yu, J., Cheng, T., Guo, H., Song, Z., Zhong, Y., Lee, T. H., Li, J., Formolo, D. A., Hussain, A., Le, K., Yao, Y., Abel, R. L., Cheung, W.-H., Lin, K., Xu, A., Cheng, K. K.-Y., & Yau, S.-Y. (2026). How muscle talks to brain: apelin protein mediates exercise-induced antidepressant effects. Molecular Psychiatry. https://doi.org/10.1038/s41380-026-03651-y