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Biology 202, Spring 2005
Third Web Papers
On Serendip

Mirror, Mirror (neurons) in the...brain?

Katherine Cheng

When asked by neuroscientist Oliver Sacks about her personal life, Dr. Temple Grandin, a famed Associate Professor of Animal Science at Colorado State University whose more humane designs of livestock handing facilities have innovated the meat-packing industry, explained that because she is autistic, she has trouble understanding other people's feelings and therefore has difficulty maintaining intimate personal relationships. She is able to function successfully in a "normal" (i.e. non-autistic) world because she has developed a mental database detailing standard scripts of behavior and their appropriate responses. For example, when she sees droplets of water seep from someone's eyes, she matches this description to a model in her head and labels it "crying." Associations of emotions that match the physical signs supplement the script so that when all the indicators are evaluated, Dr. Grandin concludes that the person is "sad." By this process of match and elimination, Dr. Grandin is able to approximate what behavior she should enact on her part to respond as social norms deem appropriate. (9)This process, of course, takes long and can become quite burdensome. The social understandings and response mechanisms intrinsic to most people become in an autistic person a systematic process requiring generous cognitive activity. Recent studies on certain brain cells called "mirror neurons" may offer greater insight as to why autistic people seem more emotionally inaccessible than non-autistic people.

Mirror neurons, which are located in a subsection of the monkey pre-motor cortex designated F5, first caught the attention of Italian researchers at the University of Parma in the early 1990s. (1) By scanning the brains of Rhesus macaque monkeys, the research team headed by Dr. Giacoma Rizzolatti observed that certain neurons activated during the performance of a task exhibited similar patterns of activity even when the monkey stayed still and watched someone else perform the task. (2) Though the monkeys were not performing the task themselves, they recognized the execution of these skills by other people. (1) Luciano Fadiga of the University of Ferrara speculated that the human brain possesses a similar system and indeed discovered similar results in the anatomically equivalent section of the human brain called Broca's area. (3)Researchers reasoned that because mirror neurons fired off electric shots in response to the actions of others, thus "mirroring" the viewed action, these brain cells must function in recognition of the action. Recently, scientists from England probed further into the function of mirror neurons and came up with some startling results.

While scientists from the University College London used a MRI scanner to record their brain activity, Royal Ballet ballet dancers and experts of capoeira, a Brazilian martial art that resembles a mix of shadow-boxing and break-dancing, watched videos of ballet and capoeira movements being performed. As a control, or a standard against which the experimented subjects were tested against, non-professional volunteers also underwent brain scanning while viewing the videos. (4) The scientists, headed by Dr. Daniel Glaser, chose to study professional dancers for two reasons, the first of which being that professional dancers are skilled in certain movements that many people are not. Secondly, ballet and capoeira feature standard movements that every professional in the art can perform. The scientists were interested in determining how viewing these different dance forms effected neuron activity in the pre-motor cortex, which functions in movement control, and in the part of the brain responsible for seeing. (5) They discovered that dancers viewing dance moves standard in their own art form experienced greater activity in their pre-motor cortex than when they viewed a dance form they were not skilled in. By contrast, the non-expert brains did not experience heightened activity in either case; rather, the non-expert brains exhibited steady neuron activity regardless of the type of dance viewed. (6)

Glaser and colleagues reasoned that the mirror neurons located in the pre-motor cortex form a "mirror system" that is specially modified to resonate with the movements and physical skills particular to each person. In the case of the ballet dancers, for example, they responded the most when viewing ballet moves because they themselves could perform the performed skills. The non-experts were unskilled in both arts. Therefore, their mirror systems did not resonate with either form of dance, which were similarly foreign to non-expert brains. Glaser reasons that the mirror system is important because it constructs a framework through which the brain can interpret information in the world. In the case of the dancers, their brains responded most to movements they themselves could perform and, thus, for which they have developed neuron pathways. These results imply that athletes and dancers can "practice" their respective skill even while physically injured. (3)Because actual movement is not required to simulate the skill in the pre-motor cortex, mentally imagining and practicing the physical movement can build neuron pathways that will enhance physical performance.

Interestingly, the mirror neuron system may also offer a greater understanding of how the brain effects social interactions. As mentioned earlier, distinct deficits in communication and social skills often characterize autism, a neurodevelopmental disorder. (6) Dr. Temple Grandin's anecdote provides one perspective of how the autistic brain does not perceive and recognize certain behaviors the same way a non-autistic brain does. In fact, researchers at UCLA medical school conducted an experiment in which test subjects were shown photographs of dinner place settings. Each photograph included a human hand, but in some photos it was obvious that the hand was clearing the place setting from a messy dinner, while in other photos it was ambiguous whether the hand was setting or clearing the place setting and if eating was just starting or ending. Brain scans of the subjects showed that mirror neurons increased activity 40 percent when the context of the image viewed was obvious (i.e. the hand was clearly cleaning the table.) Researchers speculated that in addition to recognizing actions, mirror neurons appear to play a role in understanding the intention of others. Dr. Marco Iacoboni of UCLA conducted another study in which subjects were asked to complete a psychological questionnaire while viewing images of people demonstrating various emotional states. Iacoboni observed that individuals characterized as having high levels of empathy experienced greater mirror neuron activity when viewing people in various emotional states. By contrast, subjects considered less empathetic fired fewer mirror neurons when viewing the same images. (1) Thus, in the less empathetic people, seeing expressions of motion did not resonate within their own brains; they did not "feel" as the people upon which they gazed felt.

When put through similar exercises, autistic individuals exhibit significantly different results. Hugo Théoret of the University of Montreal and Harvard Medical School and Alvaro Pascual-Leone of Harvard Medical School studied how the brains of autistic and non-autistic individuals respond to viewing hand movements. They discovered that while the pre-motor cortexes of non-autistic individuals fire more electrical signals while viewing hand movements, the mirror neurons located in the same areas in autistic individuals do not experience heightened activity. These findings suggest that autistic individuals' social deficits can be explained in part by neural—specifically mirror neuron—differences. These differences reduce an autistic individual's ability to reciprocate social behaviors, which in turn can impede the normal development of empathy. (6)Researchers attribute this difference to a dysfunctional mirror neuron system. In a study conducted by researchers at the University of San Diego, researchers found that while viewing performed movements, the brains of autistic individuals responded only to their own movement. (8)

Dr. Grandin's anecdote about how she processes external social information offers hope that therapy and treatments can be developed to teach autistic individuals how to react to certain social behaviors. Such programs would stimulate mirror neurons, thus helping autistic individuals understand the intentions of others and empathize with their thoughts and feelings, a skill essential to social behavior. (7)However, a few remaining issues that imitation treatments may not address include helping autistic individuals recognize signs that may predict behavior. Given the role played by mirror neurons in recognizing action and intention, therapies should be developed to enhance a patient's ability to read components of social situations both before and after a behavior is expressed. Furthermore, Dr. Grandin herself admits that she never "understands" because she just doesn't know what it feels like. Interestingly, one must pose the question, "Is true empathy really something that can be scripted?" Where is the actual feeling that substantiates the appropriate empathetic action?

Indubitably, men and women think differently, but a key distinction that repeats itself across cultures and time is that women generally tend to be more sensitive to emotion when making a decision. Considering how mirror neurons effect one's ability to understand intention and empathy, it would be interesting to study how the activity of these neurons may differ across genders. Furthermore, much of the research on mirror neurons has facilitated discussions regarding their evolutionary origins and functions. Some claim that it is this mirror neuron system that sets human kinds from the apes. Similarly, much of the discussion regarding women and their roles as caretakers refers to females' evolutionary roles. It would be interesting to study how mirror neurons fit into or conflict with that theory.

WWW Sources

1)The Baltimore Sun, "A close look at mirror neurons: Are these cells key to feelings of empathy?"

2)Science Daily, "Monkey Do, Monkey See ... Pre-Human Say?"

3)The Guardian, "Aping Dr Dolittle."

4)Science Daily, "Human See, Human Do: Ballet Dancers' Brains Reveal the Art of Imitation."

5)NOVA, Transcript of interview with Dr. Daniel Glaser.

6)Science Daily, "Abnormal Brain Activity During the Observation of Others' Actions."

7)Science Daily, "UCLA Neuroscientists Pinpoint New Functions for Mirror Neurons."

8)Medical Imaging Week, "Brain disorder linked to mirror neuron dysfunction."

9) Sacks, Oliver. "First Person Account," from An Anthropologist on Mars. New York: Vintage, 1996.

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