Why do babies cry when they hear another baby crying? Why can we almost feel pain when we see a hurt person? Why do we feel firsthand the problems experienced by the character in the book we are reading? The answer to these questions is found in mirror neurons.
How were mirror neurons discovered?
It all began in the late 1980s, when two Italian researchers made, by chance, one of the most important discoveries in social neuroscience. These neurophysiologists, who were studying motor planning and control, placed electrodes in the brains of monkeys. Their objective was to monitor the neuronal response of the monkeys’ brains when they performed actions such as putting a peanut in their mouth.
At one point, one of the researchers felt hungry and put a peanut in his mouth. At this point, he observed that neurons in area F5 of the brain activated, just as they did when the monkey was the one eating.
At first, the researchers thought that it was some mistake, but after repeating this behavior several times, they realized that, in fact, there was a group of neurons that were activated the same when the monkey performed the action as when it was performed. This is how they discovered mirror neurons, a very apt name since it indicates that they reflect the motor repertoire of another person.
Where are they located?
Initially, these neurons were seen in area F5 of the prefrontal cortex but later they were also discovered in the inferior parietal lobe. Apparently, the neurons in the parietal lobe are in charge of decoding everything related to the movements necessary to perform a certain action, while the neurons in the F5 would be in charge of processing the goal of the action.
In subsequent studies it was found that the mirror neurons were not only activated when the monkeys saw someone or another animal perform a certain action, it was enough for them to imagine it, for example, when they heard someone break the shell of a peanut.
These discoveries made in animals led neurophysiologists to hypothesize that mirror neurons also existed in the human brain. In recent years, several experiments have been carried out that indicate that in the human brain mirror neurons are mainly found in Broca’s area, related to language, and in the posterior parietal cortex, linked to movement planning.
What are the functions of mirror neurons?
Mirror neurons are activated from birth and allow babies to imitate the movements of adults and learn. Therefore, they are the basis of the innate capacity for imitation, without which learning would be practically impossible.
However, everything does not end there. Mirror neurons play a fundamental role in action planning. Basically, they also help us to simulate the actions before carrying them out.
One of the most interesting and controversial functions of mirror neurons is allowing us to understand what others think. Although there are neuroscientists who affirm that mirror neurons are restricted only to the simulation of motor actions, there are other researchers who consider that it would not be unreasonable to think that they are also involved in the process of simulating the intentions of others; That is, they are useful for inferring other people’s intentions.
For example, when we see someone doing a certain activity we do not limit ourselves to observing their motor movements but we go further, we not only analyze what they are doing but also why. If we see someone leaning towards the ground, we not only mentally simulate his movements but we imagine the reason for his actions, we assume that he is picking up something that he has dropped. Therefore, it can be stated that mirror neurons also help us to infer another person’s motives and thoughts.
There are even those who claim that the simulation of mirror neurons is not limited to the motor plane but includes the emotions and sensations of others. In fact, it has been observed that some areas of the brain linked to emotions are activated the same if we are the ones experiencing them or if we see other people experiencing them. From this perspective, mirror neurons would also allow us to be empathetic, put ourselves in the other’s shoes and feel what the other feels. It is no coincidence that some neuroscientists also know them as the “empathy neurons.”
References:
Redolar, D. et. Al. (2013) Neurociencia Cognitiva. Madrid: Editorial Médica Panamericana.
Mukamel, R.et. Al. (2010) Single-Neuron responses in Humans during execution and observation of actions. Current Biology; 20(8): 750-756.
Rizatti, G. et. Al. (2003) Mirror neurons responding to the observation of ingestive and communicative mouth actions in the monkey ventral premotor cortex. European Journal of Neuroscience; 17(8): 1703–1714.
