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In the mythology of Star Trek, Vulcans like Spock repress all emotions in an attempt to live a life of pure reason. In order to share experiences, thoughts, memory, and knowledge with other individuals, they resort to the Vulcan mind meld, which requires physical contact—placing the hands on the head and face of someone else to establish a conduit between brains. Humans, on the other hand, use emotion to link minds. We intuit the thoughts and motives of others by observing physical behavior and facial and bodily expressions, listening to vocal clues, and trying these out on our own neural networks. We notice the flushed face, the slight tremor of the lip, and the shift in vocal pitch and internalize these by imagining ourselves in some ways as if we were experiencing these changes. We experience these changes vicariously in the appropriate parts of our brain, and we sense the emotional state of the other person and imagine his or her thoughts. This simulation of the emotional cues of others allows us to infer their thoughts and goals, using networks of interconnected brain areas that, together, are responsible for all our various skills, behaviors, and sensations. In essence, we understand others through our understanding of ourselves.
|Neuroscientific evidence suggests that one basic entry point into understanding others' goals and feelings is the process of actively simulating in our own brain the actions....|
Q: How do mirror neurons work?
A few years ago, a macaque monkey watched an Italian researcher walk into a lab eating an ice cream cone. Giacomo Rizzolatti and his team had taken a break from studying the neurobiology of delayed gratification but had left the monkey wired to the single-cell recording apparatus. So, they noticed the surge in activity in a certain part of the monkey's frontal cortex each time it saw the researcher lift the cone to his mouth to take a lick. What these researchers discovered was that the same parts of the motor cortex used for planning actions were activated when the monkey did no more than watch someone perform an action that it found both familiar and interesting. The monkey had tasted ice cream cones before, so it knew what the researcher was doing; presumably, the monkey needed its previous experiences in order to understand the researcher's actions. And so began the discovery of a basic biological mechanism that enables us to understand the goals and to imagine the feelings of other people, a mechanism with the slightly misleading name of "mirror neurons"—an important mechanism for empathy and learning.
New evidence suggests that this neural activity of "mirroring" occurs in areas where perception and action converge. In these areas, information from our senses might tell us that it's snowing, the road is icy, and the car approaching us is going much too fast. So, we step back quickly onto the curb. These are areas of high-level sensory association (top)
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and motor planning.
Development and learning have long been understood to involve increasingly complex cycles of perception and action. We internalize our interactions, our sensory experiences, with the world and construct ever-improving skills for acting in it. But our experiences don't have to be real; they can be simulated or imagined and experienced as if they were real. Hook up a tennis player to an fMRI (functional magnetic resonance imaging scanner) and ask her to imagine playing, and neural activity will occur much as though she were running about on the court, though, not surprisingly, to a lesser degree.
Significantly, when the monkey observed the researcher pick up a pencil and use the same motion to bring it to his mouth as though he were going to eat it, there was no corresponding spike in neural activity in the monkey. This lack of activation indicates that the monkey's experiences with ice cream cones, its memory of eating and enjoying food, were critical to its empathic response. It appears that the monkey understood the goal of the researcher's action with the cone but not with the pencil; the cone-goal relationship meant something to the monkey and elicited the mental simulation of the action. So, it seems that mirror activation requires a shared understanding of the goal implicit in the actions being observed.
As a high school teacher who had once wrestled on a team in middle school, Bill always tried to attend wrestling matches at the schools where he taught. He found them exhausting. For as he watched, his body constantly tensed and contorted as he simulated the various positions and struggled in his imagination along with the wrestlers, trying to pin an opponent or escape a hold. At the end of each three-minute period, he consciously relaxed his muscles, easing himself back to a position that more closely resembled sitting. Colleagues with whom he sat at matches and who had never wrestled told Bill they tended not to have this physical reaction. It seems that understanding the goal of a certain move, like grabbing an opponent's wrist to shift his weight in order to set him up to dive at his legs and take him down, was critical to internalizing what he was watching. On the other hand, watching field hockey, which Bill never played, quickly bored him—no internal identification or understanding, no simulating the experience, and no interest.
A mirror, then, is a slightly misleading metaphor, for a mirror suggests passive reflection as opposed to a shared understanding of and active participation in goal-directed actions. Mirrors reflect whatever passes in front of them; the mirror areas of the brain are more selective. To the monkey, the researcher's action of moving a pencil toward his mouth is meaningless. The monkey has never done that, or if it has, the experience wasn't particularly memorable. So, mirror activation does not occur. By contrast, when the monkey observes the licking of an ice cream cone, which it has tasted and enjoyed, the goal is apparent, interest is engaged, and the mirror neurons fire.
It may be, then, that this "mirror" property forms the most basic biological mechanism by which we internalize and learn from another person's thoughts and actions. Although mirror neuron systems don't tell the whole story of how we process social interactions, they do provide an explanation for our ability to internalize and "read" the goals of others as a starting point to feel and understand their actions and emotions.