Archive for September 15, 2013

Autism and Empathy

What is it about the brains of people with autism that makes them so different from people with other types of mental retardation, such as Down Syndrome, or other types of mental illness, such as schizophrenia?  We still don’t know what’s driving the autism epidemic that began in the 1980’s, but the study of autism has taught us a lot about the social brain.  The new concept of autism spectrum disorders  describes the many ways our social brains can fail.

Our social brain is built on at least five areas and capacities, according to neuroscientist Eric Kandel in Age of Insight (p 411 fig 25-2).  Most infants demonstrate in the first days of life the capacity to recognize a face.  This capacity is located in the inferotemporal cortex and the amygdala.  Equally important is the capacity to recognize and attend to human bodies and to analyze their motions, located in the extrastriate body of the occipital lobe and the superior temporal sulcus. Most infants can distinguish a mother’s outreaching hand from a doll’s hand or Mr Rogers’ wave on TV.

The capacity to simulate the motions of others through mirror neurons gives the infant an internal representation of the gestures of others. Mirror neurons for movements, which fire during a gesture and during the observation of a similar gesture in another person (the outreaching hand, the smile), are concentrated in the inferior parietal cortex and inferior frontal cortex. Mirror neurons help babies (and big people) to learn by imitation.  Overlying these capacities is the capacity to infer intentions, based on memories, and to imagine what another person is thinking (“Here comes the breast.  Usually warm milk comes next.  She wants to feed me.”)—the beginnings of empathy.

The social brain is a complex set of systems, with many opportunities for failure. Some autistic children seem unaware of the presence of another person in the room, suggesting an inability to attend to human bodies or analyze their motions.  Others may notice another person but appear indifferent. Among those who glance at a face, many autistic children miss the important cues about the other person’s state of mind.

Why? Eye tracking studies  of autistic infants looking at faces found that, unlike most infants who concentrate their attention on the eyes as well as the mouth, autistic infants focus on the mouth. At an early age they miss the eyes and all the information about the mind of the other person that comes through the eyes. They may miss that critical period when children learn that people can be understood in this way. The areas of the brain that respond to eye, hand, and arm movements are relatively quiet when the infant is tracking the motion of a truck or a rubber duck.  It’s possible to be quite talented at observing things and quite impaired at observing and making sense of human behavior.

The payoff for all this new understanding of the social brain may come through intensive efforts to identify as early in life as possible those children who will later show forms of autism. Some promising early studies, such as the Early Start Denver Model  suggest it may be possible with well-timed interventions to train autistic toddlers to improve their IQ’s as well as their adaptive behaviors, such as eye tracking, their reading of facial expressions, and their capacities to think about what others might be thinking. For most of us, the capacity for empathy is innate. For some it must be learned.

Wired for Empathy

“You’re on my mind” is a loose figure of speech, until you play charades with your lover in a brain scanner.  Then you understand that she is not only on your mind but in your brain, deep.  And we know where.  We can see you lighting up right in your private parts, right there in your putative mirror neuron system and your ventral medial prefrontal cortex. That’s empathy in action.

In the 1970’s when I was in college and medical school, the only people who spoke or wrote comfortably about empathy were literary critics and psychotherapists.  Now, in Western popular culture, “empathy” has earned common clout—and it’s cool enough to have served as the name for at least three rock bands in the past twenty years.  We now have an easy word and apparent permission to talk about an aspect of human nature that is so common and complex that we have no idea how we do it.  And we can now study empathy in our brains as well as our words.

Empathy is the capacity to imagine the feelings and the condition of another person.  We’re so wired for empathy that we seem to come by it effortlessly—that is, most of us, most of the time.  As infants we imitate the sounds, gestures and facial expressions of those closest to us.  Imitation, so fundamental to learning, is the beginning of empathy.  Our drive to attach ourselves to those who help us survive pulls us early into the task of guessing what’s going on in their minds. And guessing wrong is one of the universal frustrations: infants baffled by parents, parents baffled inscrutable teenagers, Mars baffled by Venus, software engineers who can’t imagine how I think!

A window into the mystery of empathy opened in the late 1990’s with the discovery in Italy by Giacomo Rizzolatti and colleagues of mirror neurons .  While studying the motor neurons in the brains of monkeys, they noticed that a subset of motor neurons for a monkey’s hand would fire when the monkey watched another monkey reach for a banana and raise it to its mouth.  The observing monkey’s hand did not move, but some of the motor neurons for hand movement fired as the monkey watched the other monkey’s hand move.  The 10-20% of cells that fired both when the animal acted and when the animal observed the action in another were dubbed mirror neurons, part of the putative mirror neuron system.

The field of mirror neuron research blossomed with promises for understanding learning, language, empathy, how we make attachments, and how we fail to—perhaps a whole theory of mind.  But science races inch by deliberate inch, and until a few years ago, the study of mirror neurons in people had not moved beyond studying the firing of a few motor neurons while observing a single action in another person.  What we really want to study is how we understand what’s going on in the mind of another person over time.  Charades offers a test for a piece of this process.

Charades requires one person to communicate selected phrases to others by mime or gestures alone—no spoken words—against the ticking clock.  The game is designed to frustrate and reward the competing observers’ best efforts to guess what’s on the mind of the gesturer. Marleen Schippers and her colleagues at the University of Groningen in the Netherlands used fMRI brain imaging to track the activity of several regions in the brains of two people playing charades. In 2010 they published a report showing that activity in the regions of the guesser’s brain involved with mirroring gestures (the putative mirror neuron system) “echoed” the motor neuron activity of the gesturer. At the same time the area of the guesser’s brain that reflects on other peoples’ thoughts and beliefs (the ventral medial prefrontal cortex) also “echoed” the guesser’s brain activity, tightly synched in time.  Schippers called this process “resonance.”

We’re all mind readers.  We read minds in part by transforming the observed actions of others into our own motor vocabularies and then guessing their thoughts. Guessing right leads to contact, elation, empathy, and power.  Guessing wrong in charades is sometimes funny, but in life is not much fun. We’re wired to resonate.