Mirror neurons are brain cells that fire when you see someone else performing a physical action, in the same way they would if your own body were performing the action. They might be linked to sensitivity to other people’s emotions as well. Some new research demonstrates a correlation between the ability to sense the emotions of others and the strength of mirror neuron response. People were given pairs of photos of faces and had to decide either whether the photos showed the same person or whether the faces were showing the same emotion. Those who were better at identifying emotions showed more activity in the primary motor cortex when they watched video of various hand movements; there are mirror neurons in the primary motor cortex, and the measurement of activity there is considered to be a proxy for mirror neuron activity. There was no relationship between mirror neuron activity and the ability to identify whether the photos showed the same person. This article from New Scientist has more information.
Mirror neurons are hot these days, and here’s a mirror neuron story with a twist. You probably know that you don’t need to do something yourself to activate the relevant motor pathways in your brain; just watching another person perform a physical motion is enough to get your neurons going, mirroring the activity you see. How does the brain respond, though, in people who are physically incapable of making the moves they’re seeing others make? It turns out that their brains react in ways that capture the intent of the motion, even if they can’t mimic the actual motion itself. A recent study looked at 16 normal subjects and 2 aplasic subjects (born with no arms or hands). The subjects’ brains were scanned with fMRI while they watched a video of hands doing various handy things. When the hands in the video reached for a cup, the brains of the normal subjects showed activity in the parts of their brains involved in holding a cup. However, the brains of the aplasic subjects showed activity in the motor pathways responsible for moving their feet, indicating that they were mirroring the fact of cup-moving (which they can do with their feet) rather than the specific method of cup-moving. This article from Science Now has more information.
Since their serendipitous discovery in the mid-’90s, mirror neurons have become a popular field of research and have received a fair amount of media attention. Mirror neurons are brain cells that are active in both acting and observing an action; they were discovered in macaque monkeys, but occur also in humans. When you read about them, you get the impression of researchers eagerly grabbing a new tool and trying to apply it in a number of areas. It’s hard telling what place mirror neurons will ultimately hold in our understanding of the human mind, but for now they’re certainly a hot topic of discussion. This article from the Association for Psychological Science gives a nice review of our knowledge of them so far. It covers the discovery of mirror neurons and some of the studies done on them to date, the ability of very young babies to mirror the actions of others, whether the mirror neuron system is involved in conditions like autism, and the natural checks and limits on the mirror neuron system.
In this essay from Edge, neuroscientist V.S. Ramachandran discusses how the evolution of mirror neurons might have contributed to our sense of self. He proposes that mirror neurons developed before conscious awareness of self did. Having developed this nifty ability to read the minds of others and figure out what they were thinking (and perhaps anticipate how they might behave), could we have then turned this ability on ourselves and learned to figure out what we ourselves were thinking, thus developing a sense of a self that we could observe? He notes that if this is the case, the mirror neurons might have been necessary but were not sufficient, because other primates have them but don’t have the kind of self-awareness that we do. I would like to see how his proposal could be tested, and I’m also curious about how it relates to the fact that in some ways we don’t really know ourselves all that well (of course, we don’t always know other people very well either). I’m thinking in particular of Timothy Wilson’s book Strangers to ourselves: The adaptive unconscious, which describes the ways that, for a variety of reasons, our brains keep a good deal of their workings away from conscious awareness, so that what we know about ourselves is sometimes not as reliable as what others could tell us about ourselves. (I think this is related to the “Easy Question” about consciousness that Steven Pinker mentions in the essay I linked to yesterday: “to distinguish conscious from unconscious mental computation, identify its correlates in the brain and explain why it evolved.”)
And along those lines, here is a discussion on Seed Magazine’s site between evolutionary biologist Robert Trivers and linguist Noam Chomsky about deception, including self-deception. It’s a mix of political and other examples of group and self deception (including the mental gyrations of the Bush administration in the lead-up to the war in Iraq), and some data from psychology about how people describe themselves and others (tending to flatter themselves, in general, and downplay the virtues and overemphasize the failings of the other guy).
When I was first thinking about setting up the Thinking Meat Project web site, I was talking with my older son about some of the ideas behind the phrase “thinking meat”. I said something about how one of the ways we deal with the indignities and sorrows of being conscious animals is by sharing our experiences, in particular through art. When we learn about other people’s stories and their emotions, we at least know that we’re not alone. “Sharing meat,” Greg said.
Here’s an article by Daniel Goleman about the ways in which human brains can share mental states and affect each other’s physiology. (It’s in the New York Times; free registration required.) Goleman sums up the opinion of two researchers in the field thus: “emotional closeness allows the biology of one person to influence that of the other”. Goleman talks about mirror neurons, mood contagion, and how these might be related to the physical health benefits of being happily married and having a circle of good friends. It’s fascinating stuff; I’d like to see more research into the mechanisms involved and the specifics of how health is affected by the emotional climate around us.
This New York Times article describes the latest about mirror neurons, brain cells that apparently help us learn from and understand each other. Mirror neurons are present in some primates and are most sophisticated in human beings. I knew about neurons that become active both when a person performs an action and when the person observes someone else do it. (Monkeys have the same kind of mirror neurons.) If you see someone throwing a ball, for example, the same parts of your brain would activate as if you were throwing it yourself. What I learned from this article is that, more remarkably, in humans it’s not just physical actions that the mirror neurons fire for, but emotional states. Mirror neurons appear to be linked to things like learning, language, empathy, and the way that the arts affect us–in short, some of the most intriguing features of thinking meat.
Here’s an article from MSNBC on mirror neurons, brain cells that cause us to share in the mental states of others and so understand them. I’ll be interested in hearing more about how the mirror neurons work and what mental processes lead from the neurons up to our intuitive understanding of others. I’m also intrigued by the way such “mind-reading” falls short, for example when our own emotional logic or reactions are so different from another person’s that we misread him or her. Thanks to Mark for telling me about this story.