Mirroring Emotions: The Role of Mirror Neurons in Empathy

After reading an article about the role of mirror neurons in helping assuage some pain in those who experience phantom limb pain, I became very interested in what other roles mirror neurons play in the behaviors of human beings. Mirror neurons were first discovered by a team of researchers studying motor neurons in macaque monkeys who noticed that specific neurons in the ventral premotor cortex and anterior inferior parietal lobe were activated both when the monkeys performed an action (e.g. Grabbing) and when they observed someone else doing that same action (1, 6, 11, 12). In human brains, mirror neurons are thought to help explain many behaviors, including learning language, imitating motions, and the ability to understand others’ intentions and mental states. Mirror neurons, moreover, are also indicated in human’s ability to feel empathy. (1)

As defined by the Oxford English Dictionary, Empathy is “the power of projecting one's personality into (and so fully comprehending) the object of contemplation” (2). In plainer terms, empathy can be thought of as the ability to experience the experiences of someone else. The argument for mirror neurons role in empathy is quite simple: when we perceive an action or emotion of another person, a number of neurons that would become active should we ourselves be conducting that action or expressing that feeling begin to fire. Thus, we simulate the actions and emotions of those we observe.

Through functional magnetic resonance imaging (fMRI) to monitor neuronal activation, researchers have been able to monitor the activation of these mirror neurons during the experience and observation of different emotions and experiences. For example, neurons that fire both when one observes facial features and when they imitate them have been found in the premotor cortex (3); neurons that fire both when one feels pain and when they watch someone close to them feeling pain were documented in the Bilateral anterior insula, rostral anterior cingulated cortex, brainstem, and cerebellum (4), and neurons activated both when one smells something disgusting and when they watch someone else reacting to the disgusting substance have been found in the Insula and the Cingulate Cortex (5). Interestingly, it has also been found that we don’t even need to see something to have a mirror response: when participants heard a noise, the motor neurons associated with the actions needed to create that sound are activated. One example given is that when we chewing noises, neurons involved with moving the mouth are activated (6).

This article discussing the auditory mirror system and another article following up on the representation of disgust (7) also found a correlation between participants’ scores on quotients measuring empathy and higher activation of mirror neurons during observation tasks. Simply put, it seems as though people with more excitable mirror neurons behave more empathically. These differences may also be noticeable not only between individuals, but between groups as well. Indeed, it is argued that males are innately more systematic while women are more empathetic (9) and recent research shows that females display higher mirror neuron activation when viewing a human hand while men showed higher activation while watching a dot (10).

Another interesting group that may fall on an extreme side of the empathy spectrum are those with autism. Autism, a developmental disorder associated in part with poor expressive language abilities, and social cognitive skills—precisely with which we believe mirror neurons assist. Various studies seemed to find a dysfunction in the mirror system of those with autism, as the neurons of autistic participants activate only when the participant himself is moving, but not when he is observing the movement of others (11), except when observing someone very familiar to them, such as a relative (12).

Yet, if those with autism fall on the far negative side of the empathy spectrum, where do sociopaths, people who do not feel empathy or remorse, fit in? Would they also fit on the spectrum in the place as autistic individuals? Something tells me that this is a dangerous and would be decried as unmoral for the social repercussions it may have. An article written by a psychotherapist for the Washington Post takes this even suggests that there should be a new diagnosis for Empathy Deficient Disorder to categorize people who have trouble simulating other people’s emotions (8). Do the people who would warrant this diagnosis have autistic tendancies? What about sociopathic tendencies?

If we narrow the scope to pain, I would also wonder where sadists and masochists would fit in to all of this. If sadists feel pleasure at others’ pain, is their mirror system not recognizing the distress of the one in pain? Is it misinterpreting the expressions of pain as those of pleasure? Also, when observing a masochist, do we still feel empathetic pain when watching them, or do we perceive their pleasure and simulate that as well? Unfortunately, I could find no articles about the mirror systems in these populations to answer these questions. The questions do, however, raise the interesting point of subjectivity and how we each perceive the favorability of different emotions.

Another somewhat unrelated question that must be made is, when we empathize—when we simulate in our brains the emotions/experience of others—do we truly feel what the other person is actually feeling? The easy answer seems to be, “of course not,” since the observer may have no knowledge of the strength of the feeling and the cause that initiated the emotion in the observed is certainly not present to validate the emotion in the observer. Yet, the observer may indeed experience at least some of the observed person’s emotions. The neurons that fire when watching disgust are located in a part of the brain has been previously found to induce nausea when prodded, suggesting that feelings of disgust may actually occur (5). While participants were not asked to report whether they felt disgusted at the imaged of others’ disgust, this suggests that they may have. Furthermore, the concept of an emotional contagion has been established. That is, emotions can be contagious and people have a tendency of getting caught up into the emotions of those around them (13). Could this be due to mirror neurons? If emotions truly are felt when viewing someone, than my answer would be strongly affirmative. Simulating another’s negative or positive emotions, especially over a long period of time, may influence whatever emotion one was already feeling. If the simulator of the emotion was not actually feeling the emotion, I would guess that they would be in an objective enough of a stance to not let it change their current emotion.

Yet, in the article discussing pain empathy, neurons in the somatosensory cortex, sensorimotor cortex, and caudal anterior cingulated cortex only lit up when the participant felt pain themselves and not when they saw others go through that pain. The authors of this study suggest that the mirror neurons provided a means of conveying the affective correlates of pain, but not the actual sense of feeling pain, which is assumingly induced by the activity of neurons in the aforementioned areas that were only activated upon personal pain (8). This made me think back to the original article on phantom limp pain that led me to become interested in mirror neurons. This article mentioned that, despite the activation of motor neurons in the brain, we do not automatically enact the motions that we observe because our sensory systems our telling us that there is an incongruencey. That is, if we watch someone doing a handstand, our sensory neurons will tell us that we are not also doing a handstand. The same seems to work for pain: the affective but not sensory aspects are involved. But what about the other emotions? Are there sensory systems telling us that we are in fact not sad, but happy when we simulate the sorrow of someone else when we are particularly joyful? Do we get feedback from the sensors in our face telling us that we are not making a sad face and therefore cannot be sad? Or maybe we do feel the other person’s emotion, but we are quickly normalized back to our own if it is particularly strong and the observed emotion weak? Is it whichever is strongest wins? While the role of mirror neurons in empathy seem fairly clear, the question of how personal emotions differ from emotions simulated by observing others remains.

References:

1) Mirror Neuron
http://en.wikipedia.org/wiki/Mirror_neuron
2) Empathy
http://dictionary.oed.com/cgi/entry/50074152?single=1&query_type=word&queryword=empathy&first=1&max_to_show=10
3) Carr, L., Iacoboni, M., Dubeau, M.-C., Mazziotta, J. C., Lenzi, G. L. (2003). Neural mechanisms of empathy in humans: A relay from neural systems for imitation to limbic areas. Neuroscience, 100, 5497-5502
www.pnas.org/cgi/reprint/100/9/5497.pdfSinger,
4) T., Seymour, B., O’Doherty, J., Kaube, H., Dolan, R. J., Frith, C. D. (2004). Empathy for pain involves the affective but not sensory components of pain. Science, 303, 1157-1162).
www.sciencemag.org/cgi/reprint/303/5661/1157.pdf
5) Wicker, B., Keysers, C., Plailly, J., Royet, J-P., Gallese, V., Rizzolatti, G. (2003). Both of us disgusted in my insula: The common neural basis of seeing and feeling disgust. Neuron, 40, 655-664. http://www.neuron.org/content/article/abstract?uid=PIIS0896627303006792
6) ‘‘Spectrum of empathy’ found in the brain
http://www.newscientist.com/article.ns?id=dn10108
7) Jabbi, M., Swart, M., Keysers, C. (2007). Empathy for positive and negative emotions in the guystatory cortex. NeuroImage, 34, 1744-1753.www.bcn-nic.nl/txt/people/publications/empathypositivenegativegustatory.pdf
8) Empathy: Could It Be What You’re Missing?
http://www.washingtonpost.com/wp-dyn/content/article/2007/12/21/AR2007122102266.html?hpid=sec-health
9) Empathy vs. Systemizing http://glennrowe.net/BaronCohen/MaleFemale.asp
10) Cheng, Y-W., Tzeng, O. J. L., Decety, J., Imada, T., Hsieh, J-C. (2006). Gender differences in the human mirror system: a magnetoencephalography study. NeuroReport, 17, 1115-1119.
11) Autism linked to Mirror Neuron Dysfunction
http://www.sciencedaily.com/releases/2005/04/050411204511.htm
12) Mirror, Mirror In The Brain: Self-understanding And Austism Research
http://www.sciencedaily.com/releases/2007/11/071106123725.htm
13) Don’t Bring Me Down
http://news.uns.purdue.edu/Clips/2005/dec/051226.Moods.html
14) Massage Illusion Helps Amputees
http://news.bbc.co.uk/2/hi/health/7305207.stm