Bloa physiology and behaviour

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.”


• 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


• 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


• 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

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

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

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.

Bloa physiology and behaviour

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