The Mirror Neuron System

What is the mirror neuron system?

• The mirror neuron system consists of special brain cells called mirror neurons distributed in several areas of the brain

• Mirror neurons are unique because they fire both in the response to action by others

• These special neurons may be involved in social cognition, allowing us to interpret the intentions and emotions of others

What are mirror neurons?

• Rizzolati et al (2002) discovered mirror neurons by accident. They discovered that a monkey’s motor neuron became activated in the same way when carrying out an action or observing someone carrying out the same action

• This discovery has led to a new area of investigation as it implies that, contrary to what we used to think, e.g. we understand other people’s intentions using our stored knowledge, we, in fact, simulate other’s actions in our motor system and experience their intention by using our mirror neurons

How do mirror neurons work?

• Mirror neurons fire when an animal makes a movement and also when it observes another animal making the same movement. It is thought that humans also have expressions fire when facial expressions are observed in others. This firing activates feelings we identify in others. According to Iacoboni, mirror neurons can send messages to the limbic system (part of the brain that deals with emotions), so they help us ‘tune in’ with each other’s feelings, empathy. This could be the foundation of our ability to understand and empathise with others, i.e. the mirror neuron system is the foundation of social cognition

How have mirror neurons evolved?

According to Ramachandran, mirror neurons have been very influential in human evolution as they allow us to understand the intentions, emotions and perspectives of others, making it possible for us to live in large groups and complex societies. They are also present in primates, and there is some evidence of mirror neurons in birds

What is the evidence for mirror neurons?

Laboconi et al. 2005 used fMRI to show the brain activity of participants as they watched the first experimenters make finger movements and then made the same finger movements themselves. They found activity in some of the same areas of the frontal cortex and the parietal lobe in both situations

Hacker (2012) imaged the participants’ brain activity using fMRI while they were shown a film of people yawning. When they themselves yawned, they showed increased activity in an area of the frontal lobe which is thought to be rich in mirror neurons

Both these studies support the significance of the mirror neurons in social cognition as they show that an area of the brain that is thought to be rich in this type of neurons is activated when perspective-taking occurs

However, although brain scans have shown evidence of a mirror system in humans, they do not show the activity of single neurons; the smallest areas they can show contain millions of neurons, so it is impossible to say whether the mirror neurons have been isolated and studied on animals for ethical reasons so it is difficult to generalise to humans because, as far as we know, animals do not have a theory of mind

Mukamel et al. (2010) recorded activity in signal neurons of 21 patients who were being treated for epilepsy. The researchers found some neurons that were specifically active both when the individual performed a task and when they observed a task

The active neurons showed up unexpectedly in an area known for memory, the medial temporal lobe, as well as in areas where they were expected (for example, the premotor cortex)

What is the evaluation of mirror neurons?

• Critics do not doubt the existence of MNs; the issue is what role they actually play

• Churchland (2011) says a mirror neuron is just a neuron. It is simply reporting information to a higher level circuitry, which then establishes the intentions and thoughts of others. So the neuron just fires in response to action

• Heyes (2009) suggests MNs are basically the outcome of associative learning (classical conditioning) neurons become paired because they are both excited at the same time or because one regularly precedes the other

  • In other words, MNs are the result of experience rather than innate

Why has social cognition got a biological basis?

1. Neurons in the cerebral cortex are organised into four main areas: the frontal, temporal, parietal and occipital lobes.

2. Different processes, such as visual perception, involve one or more of these lobes.

   Some areas of the brain seem to have very specialised roles in cognition.

3. It seems likely that many of our sophisticated social abilities, such as theory of mind, also involve complex brain mechanisms — these may have evolved as our brains and intelligence grew. Abilities like this could have been stimulated by our complex social living.

4. Attempts have been made to connect findings from neuroscience and social psychology and combine them into more complete theories — this is known as social neuroscience.

How do mirror neurons respond to the actions of others?

• Mirror neurons are brain cells that are involved in performing an action, such as holding a cup. However, they're also active when you observe someone else doing the same action. So, whether you're actually holding a cup, or only observing someone else holding a cup, particular mirror neurons will be active.

• It's hard to record the activity of individual neurons in the brains of humans. So, studies have been done using brain scanning techniques such as functional Magnetic Resonance Imaging (MRI, see page 86), which analyse brain activity during particular kinds of behaviours. For example, lacoboni et al (1999) found that there are areas of the frontal and parietal cortex that are active when people carry out and observe actions.

What method did Di Pellegrino use when recording neuron activity?

• Electrodes were inserted into individual neurons in the premotor cortex of macaque monkeys.

• When the monkeys reached for food, the activity in the neurons was recorded

What were the results of Di Pellegrino’s study?

The neurons were active when the monkeys reached for food, but also, unexpectedly, active when they observed someone else reach for food.

What is the conclusion of Di Pellegrino’s study?

This was the first study to provide evidence for the existence of mirror neurons. Although the function of mirror neurons is not yet clear, they may help in understanding observed behaviour.

What is the evaluation of Di Pellegrino’s study?

The experiment was not designed to study mirror neurons, so the information gathered about them was limited. Also, it involved inserting electrodes into animals' brains, which raises ethical issues

Why are mirror neurons important for social cognition?

• Neurons that are active both when you do something and when you see other people do the same thing may help you understand the behaviour of others.

• Experiments with humans using fMRI show that brain areas that are active when we feel particular emotions (e.g. happiness or pain) are also active when we see others feel the same emotion. This supports suggestions that mirror neurons may be involved in empathy.

What method did Fogassi et al use in 2005 to study mirror neuron and their intentions?

The activity of 41 mirror neurons in 2 macaque monkeys were recorded as they observed a person pick up an apple as if to eat it, or pick up the apple and place it in a cup.

What are the results of Fogassi use in 2005?

Different groups of neurons responded to the two outcomes (eat or place). Also, some neurons fired after the apple was picked up but before the second action (eat or place) was carried out.

What is the conclusion of Foggasi’s study?

Different patterns of response link with different behavioural objectives and some neurons seem to predict the intention of actions. So, mirror neurons may help to understand and predict the behaviour of others.

What is evaluation of Fogassi’s study?

• Animals may behave differently under lab conditions, meaning the experiment has low ecological validity.

• Also, the experiment was carried out on monkeys, so it's difficult to generalise the results to humans — neurons in humans may not respond in the same way.

What is the evaluation of mirror neurons?

1. The function and importance of mirror neurons are not yet fully understood. For example, they may be involved in imitation, but macaque monkeys (which have mirror neurons) have a limited ability for imitation learning.

2. A connection between mirror neurons and the theory of mind (ToM) has also been debated. However, mirror neurons are found in monkeys that don't seem to have ToM in the same way that humans do. Also, fMRI research shows that ToM tests activate brain regions that aren't generally thought to be part of the mirror neuron system. It may be that mirror neurons can be involved in learning by imitation, but the development of ToM involves more than this.

3. More needs to be learnt about the development of mirror neurons. Falck-Ytter (2006) reckoned that mirror neurons start to develop during the first year of life. However, Meltzoff and Moore (1977) found that human infants can imitate facial expressions soon after birth. This could either suggest that mirror neurons have an innate basis or that imitation doesn't necessarily involve mirror neurons.

Why has social neuroscience raised issues?

1. Social neuroscience is inter-disciplinary — it involves both biological and social concepts and theories. These different types of theories may mutually inform each other - biological research can help understand social processes better, and vice versa. This means we can understand behaviour at different levels of explanation.

2. This approach may bring important insights into human social cognition (e.g. the basis of empathy). Also, some conditions associated with developmental problems (e.g. autism) might be better understood.

3. Animal experiments involve invasive methods, e.g. inserting electrodes into the brain — this raises ethical issues.