BW: What happens to us mentally as we listen to music? As we play or compose music?
DL: Listening to music invokes a lot of different mental processes. Our brains try to find a pattern in the music and predict what will come next. We’re moved emotionally. It may make us want to move our bodies. It may make us feel sad, refreshed, sexy, annoyed. The music may remind us of personal, autobiographical experiences. All of these reactions occur in different parts of the brain. Our laboratory recently found that when people listen to music together their neurons and brain waves synchronize. How cool is that?
When we play or compose music, we activate all of those same areas, and also areas involved in creativity, motor coordination, and if we’re playing with others, we need to come outside of ourselves to coordinate what we’re doing with what we think the other person is going to do.
There’s also a neurochemical story underlying all of this. Playing music with others releases oxytocin, a hormone involved in social salience. Listening to music has been shown to stimulate the immune system. The pleasure circuits that are moderated by dopamine and mu-opioids are also affected by music, both when listening and playing.
BW: You’ve been conducting work on the mathematical structure that underlies music for the past decade. One of your most-recent studies showed that patterns of consonance in music followed scale-free characteristics, suggesting that this feature is a universally evolved one, in both music and the living world.
DL: There is a family of equations that fit the so-called power law, and they are related to fractals. It was previously shown, in the 1970s, that the pitch structure of music conforms to the power law. That is, there are certain regularities in music that can be captured in a particular family of equations. About six years ago, we showed that this applied to musical rhythms as well. This year, we showed that it applies to the harmonic structure of musical pieces. The idea in general is that we humans evolved in a world with certain physical regularities, guided by natural laws. The 1/f, or fractal structure, shows up in the patterns of leaves and leaf segments on plants, and in the topography of coastlines. It stands to reason that our brains developed a sensitivity to such structures, even unconsciously, and that our art, music, and language may incorporate some of these fractal (also called self-similarity) features because we find them to be pleasing echoes of the natural world.
BW: This issue of Brain World is dedicated to the theme of growing up. Let’s zoom in to adolescence, a particularly stressful time in our lives. What’s going on in the brain, and how can we cope better with it?
DL: Adolescence is marked neurochemically by an onslaught of pubertal growth hormones and the increased production of sexual hormones. And there’s an important shift around this time. Prior to adolescence, the primary mission of the brain is to form as many new connections as possible in response to the environment — we learn to speak a primary language, to walk, to navigate, we develop hand-eye coordination, and learn how to get along with others. Around the age of 12, the primary mission of the brain shifts to prune out unneeded connections. Obviously we continue to learn, but learning starts to take on a different character — this is why, for example, so many people who learn to speak a new language in their teens speak it with an accent.
Coping with adolescence is something I don’t know anything about! Perhaps if parents, teachers, and adolescents had a better and more-accurate picture of what it’s like, they could discuss it openly.
BW: One of your studies looks at the relationship between levels of stress and empathy. What does science tell us about this correlation?
DL: There’s a well-known finding in mice that individuals are more likely to experience pain when they are with a friend than a stranger. The underlying mechanism appears to be that the stress associated with being with a stranger increases pain thresholds above those normally occurring. Researchers call this stress-induced analgesia, and with my colleague Jeff Mogil, we’ve replicated this in humans. This effect makes evolutionary sense: If you’re experiencing pain, this usually means you’re in a harmful situation. If you’re with a trusted friend, you can relax a bit, but if you’re with a stranger, you don’t know if that stranger is responsible for the pain or may act in ways that will increase your pain (or decrease your overall safety). The link to empathy is that when friends are together and one is experiencing pain, the other experiences lower pain thresholds — it’s as though the lack of stress from being with a friend allows for empathy to show. In a stranger-stranger situation, empathy doesn’t show, and the pain thresholds for both parties are raised.
Pharmacological blockage of glucocorticoid synthesis, or glucocorticoid and mineralocorticoid receptors, in the brain enabled the expression of emotional contagion of pain in mouse and human-stranger dyads, as did a shared gaming experience (the video game “Rock Band”) in human strangers (we couldn’t get the mice to operate the controls). Our results demonstrated that emotional contagion is prevented, in an evolutionarily conserved manner, by the stress of a social interaction with an unfamiliar being and can be evoked by blocking the endocrine stress response.
BW: You say attentiveness is the brain’s most-essential mental resource. Why is that?
DL: We need to focus attention in order to avert danger, find a mate, and accomplish things. Attention is a limited-capacity resource however, and we can only pay attention to a limited number of things at a time. We need to allocate it carefully, and deliberately, conserve it for when we need it, and not be seduced by the immediate rewards of multi-tasking, which happen at the expense of getting any real work done.
BW: Your new book, “A Field Guide to Lies” [editor’s note: now called “Weaponized Lies”], talks about trust in the information age. Why and how is critical thinking changing in the Information Age?
DL: My main point is that critical thinking is not changing to keep up with the unique problems of the information age. We know how to obtain information easily and quickly, but we don’t know how to discern whether that information is true or false, whether we’re looking at science or quackery. We don’t know if someone has distorted a story, graph, or statistic in order to take advantage of us, or because they are merely incompetent. “A Field Guide to Lies” is meant as a handy and easy-to-use toolkit to help everyone make sense out of news reports, medical stories, and political claims, to see through empty claims. We have to do it for ourselves because on the Internet there is no gatekeeper, no authority.
BW: Where do you see the field of neuroscience taking us in the next decade?
DL: I’m hoping that we’ll see new findings on how to delay or reverse the cognitive consequences of aging. Better drugs for treating depression, sleep disorders, and schizophrenia. Better medical practices for dealing with strokes. I think this is all doable in the coming decade — neuroscience is a very fast-moving field.
This article was originally published in the Winter 2017 issue of Brain World Magazine.
