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Psychology Unit 2

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Unit 2 Biological Approach Revision

This section explains the main things you need to know for the Biological approach but not everything is mentioned here.

Again, we would like to make it clear that this is just a revision aid and doesn't cover everything in detail, so make sure you use other resources as well as this.

The Biological Approach specification: Download spec
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3 Key Features:

  • Genetic Inheritance – characteristics via genes
  • Biochemistry – chemical activity (neurotransmitters and hormones)
  • Brain structure – what difference parts of the brain do
 

How Science works & Content

Understanding the Individual

Scanning

Scanning is used in order to study the brain and discover which areas control which functions.

PET scan: colours, to show the flow of blood (simplified)

MRI scans: black and white, an x-ray of the skull (very similar to) – more detailed and precise.


PET: Positron Emission Tomography

It is used to look at functions and studies brain activity levels

It involves injecting a radioactive tracer in to the blood stream to see where most of the blood is flowing

Greater levels of brain activity appear in different colours

Participants are scanned twice (when inactive and active)

Uses are to look at schizophrenia and/or epilepsy


MRI: Magnetic Resonance Imaging

Used to look at structure

It studies the tissues, which looks at abnormalities and can measure the blood flow

It involves injecting a dye into the body to help show organs and relevant areas

A strong magnetic field is passed over the body to pick up radio waves from hydrogen atoms in water molecules to build up a detailed image of the brain

Uses are to compare ‘normal’ and ‘abnormal’ brains, ‘old’ and ‘young’, ‘men’ and ‘women’, and assessing damage following a stroke, tumours (abnormalities)


Biochemistry


The central nervous system is made up of the brain and spinal cord

The brain within the skull and spinal cord is within the vertebrae

The biological approach focuses on the brain, as it controls our behaviour

  1. Striatum: controlling movement and speaking
  2. Hippocampus: Short term memory (STM)
  3. Corpus callosum: brain lateralisation
  4. Ventricles: schizophrenia
  5. Amydala: emotions and depression
  6. Cortex: solving problems and decision making
  7. Cerebellum: stores practical skills (long term)
  8. Thalamus: passes information from senses
  9. Hypothalamus: regulates eating/drinking/motivation
  10. Hemisphere: brain lateralisation

A synapse is a gap between two neurons so that they never meet.

We have 100 billion neurons.

This is a Diagram of the Synapse
Dr. Money: Sex-reassignment study (David Reimer)

Studies in detail

Describe and evaluate two studies relating to the Biological Approach. One must be Money J (1975) Ablatio penis: normal male infant sex-reassigned as a girl, and David Reimer’s subsequent testimony and one other


The other study chosen was:

Gottesman I, and Shields J (1966) Schizophrenia in twins,

16 years’ consecutive admissions to a psychiatric hospital

Schizophrenia in twins Gottesman and Shields


A study researching schizophrenia using twins.

Concordance rate: shared characteristics, both twins having schizophrenia

Disconcordance: only one twin has schizophrenia.


Aim:

  • To see if schizophrenia has a genetic basis
  • To replicate other previous studies that found a genetic basis to schizophrenia


Method:

Twins of the same sex, born between 1893 and 1945 and had survived to 15. 24 twin pairs.

The research method was a twin study, which incorporated the use of a range of methods to collect data including:

  • Hospitals notes
  • Case histories for twins
  • Tape recordings
  • Personality testing
  • Test to look at thought disorder.

The researchers in the study looked at the concordance rate of MZ and DZ twins with schizophrenia.

Concordance was assessed in four ways:

  1. Both twins hospitalised with schizophrenia
  2. Twins have different diagnoses’ – one has hospitalisation
  3. The co-twin has some sort of abnormality diagnosed
  4. The co-tin does not have anything.


Results:

A concordance rate for schizophrenia:

MZ twins between 35% and 58%

DZ twins: between 9% and 26%


Conclusion:

Genes play an important role in development of schizophrenia

Environmental factors must be important


Evaluation:

+ The results agree with those of previous studies, meaning it’s seen to be reliable.

+ Sampling issues are dealt with coherently, as there are many subcategories within the sample

- Although the results suggests a genetic link, it doesn’t explain the relationship further

- It only measures if schizophrenia occurs, doesn’t develop in to why schizophrenia occurs. The study contains more description rather than detail

Role of Genes in human behaviour:


A gene is a set of instructions and carries information.

Each individual has a genotype – which is his or her own genetic composition.

The phenotype is what the individual becomes after their genes interact with the environment they grow up in.

A gene consists of a long strand of DNA.

A chromosome is a double strand of DNA.

Some diseases are ‘sex triggered’ e.g. most colour-blind people are men

If one parent gives two copies of chromosome 21, the child will have Downs Syndrome.

Disease PKU: (brief)

After birth they are tested from their heels, PKU can lead to brain damage but if carefully controlled via their diet it can be diverted.


Hormones and Brain Lateralisation in gender development:

Hormones carry messages through the blood stream, affecting growth, development, mood and metabolism.

Most common illness in men: alcoholism

Most common illness in women: depression