By Prabh, Zoya, Rose, Georgia, Lucy
and Humayra
http://www.bing.com/videos/search?q=mirror+
neuron+system&docid=4599596995707135&mi
d=8D04BBC9F9C0FAD6037C8D04BBC9F9C0FAD
6037C&view=detail&FORM=VIRE1
Rizzolatti , 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—the
same area that showed activity
when the animals
made a similar hand movement.
• 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_ne
urons_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.
• 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 mirrorneurons 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.
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 .
• 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.
• 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.
• 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.