Transcript Discuss two effect of the environment on two physiological

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Discuss two effects of environment on
physiological processes:
Environmental effects on brain plasticity
Environmental stressors and physiological
processes
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What are the methodological and
ethical strengths and limitations of the
following studies?
What are the general strengths and
limitations of research? E.g. possible
applications, generalisability,
methodological problems, other possible
factors that may have influenced results
What conclusion can be drawn from the
research? To what extent is the brain
affected by environment? How much do
we know about these processes?
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Brain plasticity is a term that refers to the brain's ability to change as a
result of experience. These changes can occur as a result of learning new
things or because of damage to the brain.
Gopnick et al. (1999) describe neurons as growing telephone wires that
communicate with each other.
Experiences are processed in the brain’s nervous system, and stimulating
environments will result in increased numbers of synapses (brain
plasticity).
Environmental stimulation refers to the way the environment provides
stimulation in the form of social interaction and learning opportunities for
animals and humans. An enriched environment is characterized by
multiple opportunities to learn new things.
Researchers have used animal models to study synaptic changes in the
brain because it is not possible to use humans in deprivation experiments.
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Performed experiment with rats
Wanted to study role of environmental factors on
brain plasticity
Group 1
Group 2
Enriched environmentlots of toys
Deprived environmentno toys
Rats spent up to 60 days in their respective
environments before being killed
Unit 2: Biological LOA
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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.
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The experiment was a rigorously controlled laboratory
experiment so it was possible to establish a cause-effect relationship.
The research challenged the belief that brain weight cannot change. This
was an important finding.
There are ethical issues in the use of animals in research like this- Since
the results contributed to a much better understanding of the role of
environmental factors in brain plasticity it can be argued that the research
was justified in spite of the ethical issues.
Kolb (1999) replicated the study and also found that rats raised raised in
enriched environments showed a large increase of the length of dendrites
in cortical neurons
Can we really generalise results from animal studies to humans?
Researchers use case studies of children who
have grown up in total neglect, i.e. with little or
no experience of language, touch and interaction
with other humans.
The brains of neglected children are often smaller
and there is scientific evidence of altered brain
function (e.g. in intelligence and emotions)
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Brain scans of three
year olds who had a
normal upbringing
and those who were
severely neglected
Found differences in
brain size and
development
Curtis (1977)
 A case study on a girl (Genie) who was socially
isolated (strapped to a potty chair in an
isolated room) until the age of 11.
 She had virtually no language ability. Although
tests showed that she was highly intelligent,
her language abilities never progressed beyond
those of a third grader.
 Genie spent a lot of time alone so the period in
which she should acquire the language and the
abilities to interact with other people passed;
as a result, when she tried to learn to
speak, she only learnt words but she
was not able to make complete sentences
Watch the documentary on Genie and take
notes
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Allows us to study sensory deprivation in
humans which could have practical
applications for treating other cases
One woman sample not representative;
personal brain structure & no control on
variables.
Later studies show critical periods favourable
to behaviour but plasticity throughout life
(Gage 2002).
Ethical issues???
What do we mean by ‘Environmental Stressors’?
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An environmental stressor is any stimulus from the environment
that affects the condition of someone and may cause an
abnormality in their physiological responses.
Examples of environmental stressors include toxins, viruses,
drugs, noise, temperature, traumas, abuse, workplace stress and
life events such as relationships,
jobs and school.
PTSD
 EVERYONE SUFFERS TRAUMA AT SOME TIME. It can be
the death of a loved one; it can be war; an attack,
robbery, rape; it can be the loss of a job.
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Usually the person recovers after some time, and the
trauma fades to a memory – painful but not destructive.
Trauma, however, is not the same as the mental disorder
PTSD – Post Traumatic Stress Disorder.
What is Post Traumatic Stress Disorder?
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If the trauma is prolonged, extreme or repetitive, it can
actually physically injure the brain. The best analogy is
that the amygdala (area of brain associated with fear)
stays in the alert state so long that it gets “stuck” there.
The after effects can last for years, physical damage can
occur, and one suffers the debilitating effects of PTSD.
In about 5% of the population this may lead to PTSD
(post-traumatic stress disorder) with effects that can
last for a brief period or a lifetime.
Six criteria for a diagnosis of PTSD.
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The person goes through or sees something that involves
actual or threatened death or serious injury. The person
responds to this with intense fear, helplessness or horror.
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The person then relives this traumatic event through
dreams, or recollections. He or she can behave as if the
trauma is actually happening right then, and can react
strongly to events that even resemble the original trauma.
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The person tries desperately to avoid this, and to avoid
anything associated with the trauma, in fact, may not even
remember the trauma yet still react strongly to certain
stimuli.
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The person often has difficulty sleeping and concentrating.
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All this lasts longer than a month
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causes significant distress in daily life.
Watch the video on Post Traumatic Stress
Disorder and take notes
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Combat veterans and survivors of childhood sexual
abuse who suffer from PTSD tend to have a number
of stress related problems such as forgetfulness
and difficulty learning.
In such patients stress–related physiological
changes have been observed in the brain,
especially in the hippocampus, which play an
important role in integrating different aspects of a
memory at the time of recollection.
Task: Read through the article and make notes
about how stress can affect the brain.
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Aim: To measure the volume of the hippocampus based on the
theory that prolonged stress may reduce the volume of the
hippocampus due to increased cortisol levels.
Procedure: MRI scans were made of the brains of the participants
and participants completed memory tests (e.g. remembering a story
or a list of words). The participants were veterans and female adults
who had experienced early childhood sexual abuse. Some had
developed PTSD, but not all.
Results: The researchers found that there were deficits in shortterm memory and then performed MRI scans of the participants’
brains. They found that the hippocampus was smaller in PTSD
patients than in a control group. The veterans with most memory
problems also had the smallest hippocampus. The findings showed
a clear correlation between number of years of abuse as measured
by a trauma test, memory problems and hippocampal volume.
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The sample was very small so it is difficult to say anything
definite about the relationship between trauma and
hippocampal volume.
There could be alternative explanations to differences in
hippocampal volume (e.g. that people who suffer from PTSD
often suffer from depression as well). Depression is also
associated with reduction of the hippocampus.
However, the findings of a large reduction of hippocampal
volume in combat-related PTSD has been replicated many
times.
Knowing how PTSD affects the brain (and vice versa), however,
is very important to study. Understanding which parts of the
brain may impact PTSD can lead to the development of better,
more effective medications for the treatment of PTSD.
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Cortisol is a hormone produced by the
adrenal cortex that is produced in response
to stress and restore homeostasis.
Chronic stress may result in prolonged
cortisol secretion.
This leads to a damaged immune system and
impairment of memory and learning.
Both result from atrophy of hippocampus
(Sapolsky, 1996)
Aim: Investigate the stress from examinations and its effect on the immune system.
Procedure:
 Participants were 75 first year medical students (49 males, 26 females).
 Blood samples were taken before and during their exams.
 Immune functioning was assessed by measuring the T-cell activity in the blood
sample.
 Students were given survey for self assessment on other psychological variables e.g.
Loneliness
Results
 Samples taken during exams had a weaker immune system
 Students that claimed that they felt lonely in the survey had a more vulnerable
immune system.
Conclusion:
 Exam tress decreases the functionality of our immune system.
 Immune functioning is also affected by psychological variables.
These long term stressors may make individuals more
vulnerable to the effect of short term stressors such as
exams.
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Confounding variable: No control over other factors that might have
affected the immune system e.g. Caffeine, drugs, diet, sleep, stress
of having injection for study etc.
Correlational study: cannot identify cause and effect relationship.
Did stress cause sickness? Or did sickness cause stress?
The study uses measurable, quantitative evidence (t cell blood
count).
The study uses an unrepresentative sample (medical students) and
so the results cannot be generalised to other groups.
The study uses data that is open to
interpretation (questionnaire)
Discuss two effects of environment on
physiological processes
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Final edit of essay due on Wednesday!
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The studies and testing for Genie were funded by the National
Institute of Mental Health, and David Rigler, a scientist on Genie’s
case, agreed to care for Genie, acting as a scientist, therapist, and
foster parent to Genie for four years.
Rigler found it difficult to juggle his many roles and did not
accurately document the research project. After several warnings
from the NIMH, funding was stopped for the Genie project, citing a
failure to collect data in a scientifically meaningful way.
In the year following the loss of the research grant, the Riglers
ended their care for Genie. She currently lives in an adult foster
care home in southern, California. It’s at least the sixth home she
has lived in since the research project ended.
This leaves us with several questions: Did the team go as far as it
could go in treating Genie, or did the research get in the way? Was
this case treated ethically? What could or should have been done
differently? What can it teach us about the rewards and risks of
conducting “a forbidden experiment?”