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BIOLOGICAL LEVEL OF ANALYSIS:
PHYSIOLOGY AND BEHAVIOR
1. A small amount of brain tissue from a person cannot be distinguished from that of a
monkey.
2. The human brain produces its own natural opiates that elevate mood and ease pain.
3. The brain accounts for a larger percentage of body weight in humans than in any other
species.
4. Electrically stimulating a cat's brain at a certain point can cause the animal to cower in terror
in the presence of a small mouse.
5. Both animals and humans seem to have reward centers located in the brain.
6. We ordinarily use only 10 percent of our brains.
7. Some people can write but are unable to read.
8. If a blind person uses one finger to read Braille, the brain area dedicated to that finger
expands.
9. Adult humans cannot generate new brain cells.
10. Some people have had the hemispheres of their brains split with no apparent ill effect.
Warmup: INTRO TO BIOLOGICAL LEVEL OF ANALYSIS
What does biological perspective argue?
Behavior is caused by physiology. Humans should be
studied as biological systems.
We should also consider environment and cognition –
they interact with our biology .
This relationship is BIDIRECTIONAL, i.e. biology can
affect cognition and cognition can affect biology.
Physiological Factors
Many physiological factors can play a role in behaviour: • Brain processes• Neurotransmitters• Hormones • Genes These interact with the
environment: stress, a good
looking person walking by,
brain damage from an
accident, etc.
Nature vs Nurture debate
• Researchers debated whether human
behavior is the result of biological or
environmental factors (remember Money?)
• INTERACTIONIST approach – today’s view is a
holistic picture. They both interact.
Biological principles
1. Behavior can be innate because it is genetically
based
– Evolution may play a key role in behavior
2. Animal research can provide insight into human
behavior
3. There are biological correlates of behavior
– There should be a link between a specific biological factor
(e.g. hormone) and a specific behavior
Reductionist approach
• Biological researchers often adopt this approach
in study of human behavior – breaks down human
behavior into its smallest parts (genes, neurotran-
smitters, proteins) – reductionist approach
• Sometimes criticized as overly simplistic
• But we need a detailed understanding of how
factors interact to cause certain behaviors.
Neurotransmission – the way how
messages are sent between neurons
• Neurons (nerve cells) – building block of behavior
• 10-100 billion neurons in nervous system
• Make 13 trillion connections w/ each other
• Send electrochemical messages to brain so people
can respond to stimuli (from environment or internal
changes in body)
Mechanisms of neurotransmission
Neurotransmission
Synaptic transmission
Important to know:
How do each of these effect neurotransmission?
• Axon
• Neurotransmitters
• Synapse
• Terminal buttons
• reuptake
Neurotransmitters and their effects on human behavior
How Neurotransmitters Can Affect Behavior
• Mood, memory, sexual arousal and mental illness are
effected by neurotransmitters
• Study: Kasamatsu and Hirai (Buddhist monks) 1999 –
Aim – determine how sensory deprivation affects the brain
Method – studied Buddhist monks on a 72 hour pilgrimage
to a holy mountain. Took blood samples before and after
monks reported hallucinations
Result – found increase in serotonin levels had activated
the hypothalamus and frontal cortex
Martinez and Kesner’s experiment
• What was the aim?
• How the procedure look like?
• What are the strenghts and limitation of
Martinez and Kesner’s experiment?
Look at page 41 –
research in psychology
Activity• As a team you will develop a skit to explain:
– Neural communication
– How Neurons Communicate (synaptic transmission)
– How neurotransmitters influence us
• Create a skit, interview, or
other interactive presentation.
• Create a Title Board and
vocabulary list.
• Make sure each of your
“actors” is labeled.
The Brain and Behavior
• Early method to study the
brain was to study a case
of brain-damaged patients
over a long period of time
(longitudinally)
• Most Famous is the case
of Phineas Gage
Localization of brain function• Paul Broca (1861) found that people suffering from
damage in the left frontal lobe of the brain
(Broca’s area) were unable to understand and
make grammatically complex sentences. His
patients had trouble producing speech, but were
able to understand it.
• It’s called aphasia
• Most famous case study a young man named Tan
(only word he could say)
• Autopsy revealed source of brain damage – his
disability was the result of a specific brain trauma.
Localization of brain function
• Carl Wernicke (1874) – first to
describe area crucial for language
comprehension – left posterior
superior temporal gyrus
• His patients could produce speech,
but could not understand it. Called
Wernicke’s aphasia
• Now we more understand language
processing.
Localization of brain function
• By carrying out post-mortem studies of people with
strokes, Brocka and Wernicke concluded that
language processing is localized. It is possible to
trace origin of behavior to a specific part of the brain.
• This led to studies in localization to map out the
brain’s functions.
• Doesn’t explain all human behavior – but is a great
step forward.
Look at blue frame
Page 43
Be an enquirer
Localization of brain function and ethics in research
• Robert Heath (1950s) - experiments electrical stimulation of specific
parts of brains of depressed patients - they experienced pleasure.
• the participants press the button themselves
• during a three-hour session, the subject (B-19), electrically self-
stimulated himself 1500 times.
• “During these sessions, B-19 stimulated himself to a point that he
was experiencing an almost overwhelming euphoria and elation,
and had to be disconnected, despite his vigorous protests.”
Localization of brain function and ethics in research
• James Olds - researches on rats
• Aim: what could happen if rats’ pleasure
centers were stimulated
• The rat would receive electrical stimulation of
the nucleus accumbens by pressing a lever
• the rats were willing to walk across electrified
grids in order to get to the “pleasure lever”
• they preferred the stimulation to eating and
drinking
Localization of brain function and ethics in research
• Animal studies show that all drugs increse the production of
dopamine (desire) and reduce the production of serotonine
(satiety)
• Both neurotransmitters play a central role in the feelings
produced by such drugs as cocaine and nicotine
• Frequent consumption of drugs increases amount of
dopamine in nucleus accumbens
Localization of brain function and ethics in research
• In order to carry out researches on the nucleus accumbens
(to gain insight into the nature of addiction) animals
suffered and were killed.
• Is it ethical to use animal reserach for
betterment of human beings?
The use of technology
in brain research
Electroencephalogram (EEG)
• EEG printout is often thought as a „brainwaves”
• When neurons transport information through the brain they
have an electrical charge
• EEG register patterns of voltage change in the brain
• Understanding of: sleep, emotions, epilepsy
• Limited information – we can not reveal in deeper brain
regions
EEG
PET positron emission topography
• Scan monitors glucose metabolism in the brain
• The patient is injected with a harmless dose of radioactive glucose
• The radioactive particles emitted by the glucose are detected by
PET scanner
• Scan products coloured maps of brain activity
• Diagnose: abnormalities like tumours, changes in Alzhaimer’s,
compare brain differences in normal individuals and those with
psychological disorders (schizophrenia),
• PET (compared to MRI) can record ongoing activity in the brain,
such as thinking
PET
fMRI - functional magnetic resonance imaging
• Provides three dimensional pictures of the brain
structures
• using magnetic fields and radio waves
• shows actual brain activity and indicates which areas of
the brain are active when engaged in a behaviour
• easy to carry out
• very often used
fMRI
How the enviroment affects the brain
• BRAIN PLASTICITY – refers to brain’s ability to rearange the
connections between its neurons – the changes that occur in
the structure of the brain as a result of learing or experience.
• Every time we learn something new, the neurons connect to
create a new trace in the brain. This is called DENDRITIC
BRANCHING because the dendrites of the neurons grow in
numbers and connect with the other neurons.
Rozenweig & Bennet (1972)
• Aim: to measure the effect of either enrichment or
deprivation on the development of neurons in the cerebral
cortex
• Two settings: enriched, stimulating environment with lot of
toys and depriveted environment
• Rats spend 30 or 60 days in their cages and then they were
sacrificed
Rozenweig & Bennet (1972)
• Post- mortem studies of rats’ brains showed that rats from
stimulating environment had an increased thickness in the
cortex
• The frontal lobe (associated with thinking, planning and
decision making) was heavier
• Further studies demonstrated cortical thickness increases
when rats were placed with other rats
COMPANY + INTERSETING TOYS
= devlopment of CEREBRAL THICKNESS
Can these findings be generalized to humans?
London Taxi driver study – Eleanor Macguire (2000)
• Dr Eleanor Maguire scanned the brains of 16 London black-cab
drivers, who had spent an average of two years learning 'the
Knowledge' – street names and routes in London.
• The taxi drivers had a larger right hippocampus than control
subjects, and the longer they had been on the job, the larger
their hippocampus size.
• These findings seem to indicate
that the right hippocampus plays
an important role in storing spatial
memories
Read the study and answer the following questions
• Why were london taxi drivers chosen as subjects in the study?
• Which part of the brain were they investigating and why?
• What variables were controlled in this study?
• Who were the control group and what is the purpose of having a control
group?
• What two research methods were used?
• How does the first method differ from a lab experiment?
• Outline the results of the study
• What other variable could explain the differences found?
• What are demand characteristics?
• State one criticism of the study
London Taxi driver study – Eleanor Macguire (2000)
• Significantly greater volume of gray matter was found in only one brain
area in the taxi drivers: the left and right hippocampi.
• The posterior hippocampus had more gray matter bilaterally (both sides)
in taxi drivers than in controls.
• The anterior hippocampus had more gray matter bilaterally in the
controls than in the taxi drivers.
• Read the study on page 47: Richard Davidson (2004)
• Could meditation change the brain activity?
Mozart effect?
How the enviroment affects the brain
• Mirror neurons are neurons that fire
when an animal performs an action or
when the animal observes somebody
else perform the same action.
• Gallese research (1996) with monkeys
and peanuts
• Iacoboni reserch (2004) with human
faces
• Mirror neurons - empathy for others
Functions of Hormones in Human Behavior
• Hormones – chemicals that
affect behaviour
• They are produced by the
glands that make up the
endocrine sysytem
• hormones enter directly
into bloodstream
The endocrine system
HORMONE GLANDS FUNCTION
Adrenaline AdrenalsFlight or fight
response, arousal
Cortisol AdrenalsArousal, stress
hormone, memory
Melatonin Pineal Regulation of sleep
OxytocinPituitary and
hypothalamus
Mother-child
attachment
Testosterone and
oestrogenGonads Development, emotion
Oxytocine
• Produced by hypothalamus after being
stimulated by the pituarity gland
• Plays a role in inducing labour
contractions and lactation
• It is released with touches and hugs
• Associated with bonding between:
– mother and child
– lovers
• „love hormone”
Melatonin
• Production of melatonin by pineal gland is stimulated by
darkness and inhibitted by light
• Melatonin level in bloodstream peak in the middle of the
night, and gradually decrease towards morning
• When winter approaches – we become tired earlier
• Melatonin release correlates with the circadian rhythm –
biological clock
Seasonal affective disorder
• Rosenthal (1987) found that higher levels
of melatonin contribute to seasonal
affective disorder (SAD) – a subcategory
of depression that is characterized by
sleepiness and lethargy – as well as
craving for carbohydrates.
• Reduced levels of sunlight in fall and
winter are believed to disrupt circadian
rhythms in certain people leading to this
form of depression.