Mirror neuron

Mirror neurons are active when a primate performs an action, but also when it observes that action. So far these neurons had been seen in Broca’s and premotor cortical areas of the brain.

See for example this (slightly hyperbolic) essay by Ramachandran on their potential importance in imitation and language http://www.edge.org/3rd_culture/ramachandran/ramachandran_p1.html

See also

• NOVA scienceNOW: Mirror Neurons -- including a 14 minute broadcast segment.

What is mirror neurons?

Definition: A mirror neuron is a neuron which fires both when performing an action and when observing the same action performed by another (possibly conspecific) creature

By many scientists said to be one of the most important findings of neuroscience in the last decade. As V.S. Ramachandran stated in his article on imitation learning; “The discovery of mirror neurons will do for psychology, what DNA did for biology”.

So what is it? Well let’s break it down.

Mirror neurons are receptors in the brain, on monkeys physically placed in the frontal lobes of the brain. These receptors are active when the monkeys perform certain tasks, but they also fire when the monkeys watch someone else perform the same specific task. Scientists have found evidence of a similar system (matching observations with actions), existing in the human brain. The mirror system is often considered to represent a primitive version of the simulation heuristics that might underlie mind reading, as well as being the first link between observing others performing a task and thereafter imitating or duplicating that very movement. Scientists all over the world, studying human behaviour and language learning (as well as other imitative actions), all agree that mirror neurons play a major explanatory role in the understanding of their studies.

Autism, or other deficits, is meant to be caused by damages in these cerebral structures. But mirror neurons are also believed to be the basis of all imitations causing a child to learn how to walk, talk and behave like their parents or any other adult. Scientists are therefore doing extensive research on this phenomenon, since this could provide mankind with a ‘cure’ for autism or simply improve the humankind’s mental abilities.

Who discovered them?

The lead scientist on this discovery is Professor Giacomo Rizzolatti of the university in Parma, Italy. Working with him, at the time of discovery, was two other scientists; Leonardo Fogassi and Vittorio Gallese. They were, through their work on a study of monkeys motor-neurons , trying to prove that in the bark of the brain, there were nerve cells specialized for each possible movement, e.g. grabbing an object, picking items up, etc. A theory they ended up proofing right, but with the discovery of mirror neurons, this small breakthrough was left in the shade.

During their study of motor neurons, they placed electrodes in particular brain cells of a monkey, then by giving the monkey food, they would try to measure the neurons reactions to certain movements.

As many other great discoveries, this was made by pure coincidence. Rizzolatti explains; “I think it was Fogassi, standing next to a bowl of fruit and reached for a banana, when some of the neurons reacted. How could this happen, when the monkey did not move. At first we thought it to be a flaw in our measuring or maybe equipment failure, but everything checked out OK and the reactions was repeated as we repeated the movement”.

The small group of scientists soon realized this to be a great discovery and they started immediately to try and find the same reactions in humans. Only difference was that you can not just place electrodes in a living human brain, so they had to measure through a brain scanner. These tests and measurements confirmed the previous tests with the monkeys immediately, creating a whole new basis of understanding the human perception. Though this is still an area difficult to grasp, a lot of scientists work every day to try and map these receptors and by mapping they hope to unveil some of the secrets in our head. V. S. Ramachandran believes that the discovery of mirror neurons will provide a unifying framework and help explain a host of mental abilities that have until today remained mysterious and inaccessible to experiments. Only time will tell.

Evolution

The hominid brain almost reached its present size, and maybe even present intellectual state, approximately 25.000 years ago. Still a lot of the attributes regarded as unique for humans appeared a lot more recent. This provides us with a lot of unanswered questions; So what was the brain doing during that period of ‘incubation’? Was all the potential for creating fire, arts, music and maybe even language already present at that time? And if that is the case, why has those abilities been slumbering until a far more recent time? Why did the great leap in technological sophistication, widespread cave art, clothes, stereotyped dwellings, etc. happen around 40 thousand years ago, even though the brain had achieved its present "modern" size almost a quarter of a million years earlier? Did language appear completely out of the blue as Chomsky suggests? Or did it evolve from a more primitive gestural language that was already in place?

Some of these questions have been asked by many a scientist through the past decade. One of these scientists is V. S. Ramachandran. Ramachandran believes that language evolved mainly due to the need of producing emotional calls and musical sounds during courtship. Once those needs were fulfilled, the brain could begin the evolution of the spoken language. This is where the discovery of mirror neurons fits in.

As previously mentioned, the mirror neurons are certain cells that fire when performing an action, for example pulling or pushing an item. Different neurons will fire for different actions, tempting us to believe this could be a sort of motor neurons. However these neurons also fire, when we see others performing a task, even though we are not moving. This situation is most likely what enables us to foresee, read or even understand others intentions. So, if we can understand mirror neurons (and understand their behaviour) we have the basis to become a real ‘mind reader’. Apparently for some people, these mirror neurons can fire prior to the actions performed by others, meaning that it is possible for them to predict their actions. A few scientists believe that this could be the reason, for so many heroic tales of the past, for instance the great martial artists of the Shaolin Order . It is possible that these ‘fighting monks’ had the possibility to foresee an eventual attack and thereby counterattack or defend themselves. With a lack of, or even damage to, these mirror neurons, we would no longer be able to understand or empathize with other people emotionally and therefore we would probably completely withdraw ourselves from the world socially, resulting in an autistic state of mind. So if it one day is possible to ‘repair’, or maybe even replace, some of these neurons it could very well mean the end to autism in the world.

Ramachandran did a study, to map mirror neurons behaviour, on humans instead of monkeys. His study was based on a group of patients with the strange disorder called anosognosia . Most patients suffering from a stroke in the left hemisphere have complete paralysis of the right side of their bodies, these patients normally complaints about their paralysis. 5% however will not complaint, since they will deny the fact that they are paralyzed even though they are in the same condition mentally as before the paralysis occurred. In Ramachandran’s study group they where amazed at the fact that not only did the patients deny their own paralysis but some actually denied their fellow patients as well, even though the paralysis was clearly visible to them. So why would a patient deny another patient’s paralysis? The small group of scientists came up with this conclusion: “It's as if anytime you want to make a judgement about someone else's movements you have to run a VR (virtual reality) simulation of the corresponding movements in your own brain and without mirror neurons you cannot do this”.

Next Ramachandran believes he, along with Eric Altschuller and Jamie Pineda, has proven the existence of mirror neurons by monitoring brain waves. When people move their hands, a brain wave (called MU) gets blocked and disappears immediately. The three scientists suggested, at the Society for Neurosciences in 1998, that this was indeed caused by the mirror neurons, as found by Rizzolatti. To back their suspicion and theory, the group found that such suppression occurs when a person observes a hand movement performed by others, but not if the same person observes a similar movement by an inanimate object. This means that children with autism should show suppression if they move their own hands but not if they watch others moving their hands. This has yet to be confirmed though, but preliminary hints indicate that this might be the case.

Mirror neurons obviously cannot be the only answer to all these riddles of evolution. After all rhesus monkeys and apes have them, yet they lack the cultural sophistication of humans (although it has recently been shown that chimps at least DO have the rudiments of culture, even in the wild). Concerning the “big bang”, or at least great leap in human evolution, 40.000 years ago, there may indeed have been a genetic change in the hominid brain, but it may not have been an increase in the ability to innovate, but more likely an increase in the sophistication of the mirror neuron system and therefore in our ancestors learning ability. The resulting increase in ability to imitate and learn (and of course teach) would then explain the explosion of cultural change that we call the great leap forward in human evolution. This argument implies that the whole "nature-nurture debate" is largely meaningless as far as human are concerned. Without the genetically specified learning abilities that characterizes the human brain Homo sapiens wouldn't deserve the title of sapiens (wise), but without being immersed in a culture that can take advantage of this learning ability, the title would be equally inappropriate. In this sense human culture and human brain have co-evolved into obligatory mutual parasites — without either, the result would not be a human being.

When we think about the time 40.000 years ago, the great leap gave us the potential to create art and tools and also the first linguistic skills, we think of it as being a dramatic change in human evolution. But when we think of the 19th century, we like to call it the industrial (or even scientific) revolution. Is it not a giant leap with nuclear power? Or Air travel? Or walking on the moon? There is still no proof of a genetic change in the human brain concerning this ‘second giant leap’. However we do know that the last leap occurred exclusively because of fortuitous environmental circumstances. So it makes no more sense to ask "Why did sophisticated tool use and art emerge only 40.000 years ago even though the brain had all the required latent ability 100.000 years earlier?" — Than to ask "Why did space travel occur only a few decades ago, even though our brains were pre-adapted for space travel?”. These questions ignore the important role of contingency or plain old luck in human evolutionary history.

Technological

Two Japanese scientists and robotics engineers, Hideki Kozima and Hiroyuki Yano from the Communications Research Laboratory in Kyoto, Japan, are at this moment trying to create an infant-like humanoid robot with three goals;

1. The acquisition of intentionality, which enables the robot to intentionally use certain methods for obtaining goals.
2. Identification with others, which enables it to indirectly experience other people's behaviour.
3. Social communication, in which the robot empathetically understands other people's behaviour by ascribing to the intention that best explains the behaviour.

These three goals all describe some of the functions, the mirror neurons provide humans with. Should this humanoid robot be able to fulfil their goals, it would mean it is able to learn how to predict human behaviour, how to speak any language presented to it and maybe even how to teach humans its new found capabilities.

But for now, the two robotics engineers are having their difficulties. The “babybot” does not seem able to comprehend, and later engage, an intentional activity of speech acts, such as making a promise.

At the current stage, the humanoid does not exactly look human, but some of the specifications of it could actually be compared to that of a human. E.g. this picture is from the humanoids 3-year birthday. As described it has 25 DOFs , used to simulate facial expressions, as well as speech recognition and stereo vision.

The Infanoid is, in this picture, mounted on the tabletop allowing the human caregiver to interact directly with it. For this interaction to be possible it needs some basic functions.
These functions could be, but are not limited to:
1. Tracking an non-specific human face in a cluttered background
2. Determining roughly the direction of the human face being tracked
3. Tracking objects with salient colour and texture, e.g. toys
4. Pointing to or reaching out for the object or face by using the arms and torso
5. Gazing alternately between the face and object
6. Vocalizing canonical babbling with lip-synching.

Currently, the two engineers are working on modules for gaze tracking, imperfect verbal imitation, in order to provide Infanoid with the basic physical skills of 6-to-9-month-olds, as an initial stage for social and communicative development.

So this could be the future? Humanoids with the possibility to simulate human behaviour? Maybe even produce special communication guidelines, such as humanoid language?

Based on all the materiel concerning mirror neurons and their effect on our lives as we know it, the scientists all agree on one point; This area is still a great unknown, so none of us can give a conclusive answer to what the future might bring, concerning the use of mirror neurons one way or another. Therefore this piece will inevitably become inconclusive as well, however dissatisfactory this might be.

--JB 09:19, 27 Apr 2005 (UTC)

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References:

- The others are inside you, article from “Ingeniøren” (original title: “De andre er inden I dig”).
- MIRROR NEURONS and imitation learning as the driving force behind, authored by V. S. Ramachandran.
- What do mirror neurons mean…?, workshop sponsored by The European Science Foundation.
- A Robot that Learns to Communicate with Human Caregivers, authored by Hideki Kozima and Hiroyuki Yano.
- Neuroscience And Bio Behavioural Reviews, www.elsevier.com/locate/neubiorev.
- The Internet and various user forums.

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