Transcript File

Objective 2.4:
*Discuss two effects of the environment
on physiological processes.
*section B essay question
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Things to consider….
 Early 20th century: believed that brain was only
influenced by genes and thus unchangeable
 Now we know that environmental enrichment
/deprivation(an environmental factor) can modify the
brain (a physiological process).
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Two effects:
 The effect of Enriched Environments on Brain Plasticity
 The effect of the environment on mirror neurons.
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Environment and
Brain Plasticity
 Neuroplasticity is a term referring
to the ability of physiological
processes in all species to change
structurally and functionally as a
result of input from the
environment
• Plasticity occurs on a variety of
levels, ranging from cellular
changes involved in learning, to
large-scale changes involved in
cortical remapping in response to
injury and disease.
•
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Environment and
Brain Plasticity
 The idea of Brain Plasticity
suggest that the brain has the
ability to rearrange
connections between its
neurons-that is, the ability for
the brain to physically
change due to learning or
experience.
 The changes represent our
brain’s adaptation to the
environment.
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1. Environmental Enrichment
• Neurons can compensate for injury or
disease or to adjust their activities in
response to new situations or changes in
the environment. The brain is most plastic
early in life (This is known as the critical
period).
• The brain can rearrange the connections
between neurons (dendritic branching)
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Environment and Brain
Plasticity
• The brain can generate new neurons
throughout life (neurogenesis)
• Learning can increase/decrease
neurotransmission between specific
neurons (long term potentiation)
• It is assumed that as your behavior
changes (in most cases because of
environmental change), so does the
underlying neural circuitry.
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Effects of environmental enrichment on
brain plasticity.
 Environmental enrichment concerns how the brain
is affected by the stimulation of its information
processing provided by its surroundings (including
the opportunity to interact socially).
 Brains in richer, more stimulating environments,
have increased numbers of synapses, and the
dendrite arbors upon which they reside are more
complex.
 This effect happens particularly during
neurodevelopment, but also to a lesser degree in
adulthood.
What does this suggest?
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Rosenzweig & Bennett
(1972)
• Aim: To investigate the effect of enrichment
or deprivation on the development of
neurons in the cerebral cortex in rats
• Research method: Experiment
• Procedure: Rats were placed in either a
stimulating environment (toys) or a deprived
environment (no toys).
• The rats spent 30 or 60 days in their
environment and then they were dissected.
Rosenzweig & Bennett
(1972)
• Findings: Post mortem
studies of the rats´ brains
showed that those that
had been in a
stimulating environment
had an increased
thickness in the cortex.
Kolb (1999)
• Aim: To investigate if stimulating environments
affect the growth of neurons in rats
• Research method: Experiment
• Procedure: Rats were placed in enriched
environments beginning at weaning or as young
adults. Control group were placed in standard
cages
Kolb (1999)
• Findings: Both age
groups raised in
enriched
environments
showed a large
increase of the
length of dendrites in
cortical neurons.
Research on environmental enrichment
cont.
• Two important and consistent findings have
emerged from this type literature.
o First, and not surprisingly, rodents learn and
remember better in an enriched environment.
o Second, neurogenesis (the creation of new
nerve cells) is increased in an enriched
environment, specifically in the hippocampus.
o Thus, animal studies showing the benefits of
environmental enrichment provide important
corroborating evidence.
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Research on environmental enrichment
cont.
•
Such studies suggest that brains are physically sculpted
by our environments. Aspects of the brain can be
changed as we go through experiences. As a person
develops a greater number of skills and abilities, the
brain actually becomes more complex and heavier.
•
Research has also suggested that Children who are
unable to have certain experiences, will have specific
parts of their brain significantly less developed, less
intricate, and thinner in comparison to those who have
had those experiences.
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Research on deprivation and brain damage.
• According to the principle that states animal
research can be used in place of human
because of their biological similarities, we can
infer that a lack of stimulation (deprivation—
such as in old-style orphanages) delays and
impairs physiological parts of the brain
responsible for cognitive development.
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Extra Credit Summary: The Case of Genie
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Responding to the environment
Have you ever have a sensation where you’re watching
someone do something and you can just feel exactly what
they must be feeling, as if you were in their shoes?
Think of an example.
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Mirror neurons and the environment.
•
Another way in which the brain and environment
interact is through the activity of the recently discovered
mirror neurons. Mirror neurons are neurons that fire when
an animal performs an action or when the animal
observes somebody else perform the same action.
This means we subconsciously mimic the actions of
others and thus share, to some extent, their experience.
How can this be effected by your environment?
•
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Mirror neurons and the environment.
• Scientists have long wondered why we get that
feeling, and more than two decades ago, a
team of Italian researchers thought they
stumbled on an answer.
• While observing monkeys’ brains, Gallese et. Al
(1996) noticed that certain cells activated both
when a monkey performed an action and when
that monkey watched another monkey perform
the same action. “Mirror neurons” were
discovered.
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Mirror neurons and the environment.
• Scientists have long wondered why we get that
feeling. A team of Italian researchers thought
they stumbled on an answer.
• While observing monkeys’ brains, Gallese et. al
(1996) noticed that certain cells activated both
when a monkey performed an action and when
that monkey watched another monkey perform
the same action. “Mirror neurons” were
discovered.
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Mirror neurons and the environment.
http://www.ted.com/talks/vs_ramachandran_the_neurons_
that_shaped_civilization.html
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2. Mirror neurons and the environment.
•
The proposed mechanism is rather simple. Each time an
individual sees an action done by another individual,
neurons that represent that action are activated in the
observer’s premotor cortex.
•
This automatically induced, motor representation of the
observed action corresponds to that which is
spontaneously generated during active action and
whose outcome is known to the acting individual.
•
Thus, the mirror-neuron system transforms visual
information into knowledge.
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Mirror neurons and the environment.
•
These mirror neurons, as they are known, also allow us to
know what another person is feeling, without having to
think about it.
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The discovery of mirror neurons is among the most
significant neuroscientific discoveries in recent years.
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This mean that when you see someone doing
something, in your brain you do it too - for instance,
when you watch a person running, the bit of your brain
concerned with planning to move the legs is activated.
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Mirror neurons and the environment.
•
When you see another person expressing an
emotion, the areas of your brain associated with
feeling that emotion are also activated, making
emotions transmittable.
•
Emotion mirroring is thought to be the basis of
empathy. Autistic people often lack empathy and
have been found to show less mirror-neuron
activity.
•
Mirror neurons explain why emotion is whipped up
in horror film audiences - seeing someone else
looking frightened makes you feel scared yourself.
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•
More Info:
http://www.robotcub.org/misc/papers/06_Rizzolatti_Crai
ghero.pdf
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