Reciprocal Inhibition
The other day, I was doing a stretching class on the Peloton app. Four minutes in, the instructor had us in a kneeling lunging hip flexor stretch. If you want to get a deeper stretch, she said, here’s a trick. The technical term is “reciprocal inhibition,” she said—if you squeeze your right glute, your left hip flexor will relax and loosen, allowing you to lean into the stretch even more. It worked. So I squeezed various other muscles and noticed the relaxation of opposing muscles, and I’ve been thinking of and looking for other examples of reciprocal inhibition and opponent processors since…
The Left and Right Hemispheres
“The brain is,” Iain McGilchrist writes in The Master and His Emissary, “a system of opponent processors.” Before McGilchrist, the neurologist Marcel Kinsbourne said the brain is “overwhelmingly an arena of reverberating reciprocal influence.” Before Kinsbourne, nature got there first, McGilchrist writes, “beginning with a remarkable physical division at the core of the brain, which she has since made more robust through mechanisms of interhemispheric inhibition.” The Master and His Emissary is flooded with examples of reciprocal inhibition. There are two types of attention, for instance: focus attention (left hemisphere) and open attention (right hemisphere). Focus attention inhibits open attention, and vice versa. You’ve experienced the tip of the tongue phenomenon. The harder you try, the more you recruit left-hemisphere focus attention, the less you can remember the word (it is stored somewhere in the right hemisphere). Once you stop trying, you permit a broadening of attention (right hemisphere), and the word comes. “Stimulation of neurones in one hemisphere,” McGilchrist says, “[is] followed by a prolonged inhibitory arousal in the other.” He says, “this reciprocity goes to the core of our being.”
The Parasympathetic and Sympathetic Nervous Systems
Moving from the brain to the nostrils, “breathing is,” James Nestor writes in Breath: The New Science of a Lost Art, “a power switch to a vast network called the autonomic nervous system.” There are two sections of the autonomic nervous system: the parasympathetic nervous system and the sympathetic nervous system. The parasympathetic (activated by breathing through the left nostril) stimulates relaxation. The sympathetic (activated by breathing through the right nostril) stimulates action. Like focus and open attention, activating the parasympathetic inhibits the sympathetic, and vice versa. In 2015, researchers at the University of California, San Diego, studied the breathing patterns of a schizophrenic woman for three straight years. They found that she almost exclusively breathed through her left nostril, “as a result prodding her imagination to run amok.” The researchers taught her to breathe through her right nostril to inhibit the “creative part” of her brain, “and she experienced far fewer hallucinations.”
The Body and The Mind
“We treat the body rigorously,” Seneca wrote almost two thousand years ago, “so it will not be disobedient to the mind.” And almost two months ago, I got an email from the neuroscientist Andrew Huberman. In it, he talked about the science-proven benefits of cold exposure (read: treating the body rigorously). I take a cold shower every morning. I’ve been doing it long enough that I can’t remember when or why I started doing this, and I still do not want to do it every morning. “By forcing yourself to embrace the stress of cold exposure,” Huberman told me, “you exert what is called ‘top-down control’ over deeper brain centers that regulate reflexive states.” When you inhibit that part of your brain that is telling you not to take the cold shower, it builds “what people refer to when they talk about ‘resilience and grit.’ Like the “go” and “no-go” circuits, this skill is “generic”—every time you get in the cold shower you don’t want to get into, you get better at dealing with real-world stressors. “In other words, deliberate cold exposure is great training for the mind.” Which is why, Seneca was a self-described “cold-water enthusiast.”
Strengths and Weaknesses
After spending over 10,000 hours working with the billionaire Reid Hoffman, Ben Casnocha wrote about what he learned from Hoffman. Number four: Every weakness has a corresponding strength. After a meeting where Casnocha explained to Hoffman what he believed were his personal strengths and weaknesses before sharing how he planned to compensate for those weakness, Hoffman warned Casnocha, “Most strengths have corresponding weaknesses. If you try to manage or mitigate a given weakness, you might also eliminate the corresponding strength.”
The Bigger, The Smaller
In a video of Jay-Z and Rick Rubin in the studio working on “99 Problems,” we see the moment Rubin has and suggest the idea to open the song with a cappella. This—taking away, subtracting, moving towards simplicity—is characteristic of Rubin. On the very first album Rubin produced, the credit he took was, “reduced by Rick Rubin,” instead of, “produced by Rick Rubin.” “I like to get to the essential,” Rubin said. “There’s a sonic benefit: the less elements you have, the more you can hear the ones that are there, and they sound better. And the less elements, the more space there is to hear the personality of the elements that are there.” For example, Rubin says, if you record ten people simultaneously playing the same guitar part, it sounds like guitar. But, if you record one person playing that guitar part, it sounds like a person playing the guitar. “And often in the studio,” Rubin says, “when you try to build upon things, when you add layers to try to make it sound bigger—often, the more things you add, the smaller it gets.” Reciprocal inhibition.