By Prabh, Zoya, Rose, Georgia, Lucy and Humayra

Mirror neurons

http://www.bing.com/videos/search?q=mirror+neuron+system&docid=4599596995707135&mid=8D04BBC9F9C0FAD6037C8D04BBC9F9C0FAD6037C&view=detail&FORM=VIRE1

Youtube Clip

IntroductionRizzolatti , an Italian researcher, stumbled across an unexpected discovery when experimenting on macaque monkeys to study the brain activity during different motor actions, including the clutching of food.One day, as the researcher reached for his own food, he noticed neurons begin to fire in the monkeys’ premotor cortex—thesame area that showed activitywhen the animalsmade a similar hand movement.

Does the mirror-neuron system exist in humans?

• Rizzoletti et al (2006) got human participants to either watch the experimenters making various hand gestures or to make the gestures themselves. Either way the neural activity in the hands was very similar.

PET scans identified the following brain areas as being involved:• Superior Temporal Sulcus (STS)• Responds to seeing body parts move• Inferior Parietal Lobule(IPL)• Seems similar to the area involved in monkeys• Inferior Frontal Gyrus (IFG)

Also, Ramachandran

http://www.ted.com/talks/vs_ramachandran_the_neurons_that_shaped_civilization.html

Neuroscientist Vilayanur Ramachandran outlines the fascinating functions of mirror neurons. Only recently discovered, these neurons allow us to learn complex social behaviours, some of which formed the foundations of human civilization as we know it.

Umilta et al (2001)

• The researchers got monkeys to watch experimenters carrying out various actions.

• In the first condition the experimenter is seen to reach for an item of food.• In the second condition , the item of food is hidden from view behind a

screen. The researcher then reaches for it as in condition 1, but this time cannot be seen accessing the food.

Findings• Even when the food was hidden, more than 50% of the mirror-neurons still

fired and half of these did so as strongly was when the food was in view. Umilta et al concluded that the monkey brains were responding to the understanding of what the action entailed (i.e. getting food) even though the food could not be seen.

• As a further test to show that it wasn’t the action per se that was triggering the mirror neurons, there was a third condition in which no food was hidden and the monkeys watched the same action as in condition 2. This time the mirror neurons did not fire. Clearly the firing was triggered by the understanding of the action.

Evaluation…Depretto et al (2000) compared autistic children with non-autistic children as they either watched or attempted to imitate one of five facial expressions., (anger, fear, happiness, neutrality, or sadness) Findings:• Autistic children showed less activity in the MNS as they watched or copied the expressions • The greater the autistic symptoms the lower the level of activity recorded.

Gallese et al (1996) measured the brain activity of monkeys performing a grasping action. Later when monkeys observed other monkeys making the same action their brain activity was the same. This is the basis of the mirror-neuron system. The researchers concluded that this system allows for the action and understanding of others’ actions. Behaviours we perform ourselves result in very similar brain activity to those similar behaviours we observe.

support

Ramachandran et al (2000) used an eletroencephalogram to measure children’s brain waves. They found that when an autistic child made a simple voluntary movement the MU wave was suppressed like with normal children. However when the child watched someone else perform the action the MU wave was not suppressed.Researchers conclude the Mirror Neuron System was deficient in autistic children.

• Many researchers have pointed out that this theory of autism is overly simplistic, and mirror neurons alone cannot explain the deficits found in individuals with autism (meaning it is far more complex than just being to do with neurons, and therefore means it is a REDUCTIONIST).

• Animal research is a strong AO3 – how can results be inferred from studies that have been done on Monkeys? They are not human beings so therefore the results can never be assumed to be the same for humans.

• In agreement with Gopnik, (who suggested that mirror neurons arise through experience rather than biological sources) Hebb suggested the theory of cell assemblies, in which neurons form a connection, meaning they can change and grow. Mirror neurons therefore may not be present at birth but develop through the process of association due to experience… This supports the NURTURE over NATURE debate .

Criticisms

• A majority of studies on Mirror Neurons have been conducted using animals, primates in particular.

• Validity can be questioned as it is impossible to determine the actual cause of behaviour, or infer results.

Animal Research

• Humans cannot however be used in such studies due to ethical guidelines, such as protection from harm.

• Cost benefit must be performed, as although there will likely be harm caused to animals, the positive outcome of the research and the knowledge gained is thought to override this.

Animal Research

Nature/Nurture Debate• Mirror Neurons are biological adaptations

for action understanding, which suggests that the behaviour of individuals with brain disorders may be due to their genetics.

• Mirror Neurons come from sensorimotor experience, which we gain from interaction with others and our environment, so they can be seen as both nature and nurture.

• Understanding how and why we develop empathy for others• New knowledge about autism, schizophrenia, and other brain disorders • Development of a new theory about the evolution of language.• New therapies for helping stroke victims regain lost movement.

Implications