Biological Psychology

Structure and Role of the Neurone:

Neurones are electrically excitable cells in the nervous system than function to process and transmit information.

One end contains dendrites with the centre of the cell being the nucelus connected to the axon terminal at the other end via schwann cells (covered in myelin sheath with a node of ranvier connecting each one).

Function of Neurotransmitters:

Neurotransmitters are the chemical agents secreted across the synaptic cleft, transfiring information from one neurone to another.

• Dopamine: movement, attention and learning.
• Serotonin: mood, sleep, aggressiveness.
• Endorphins: pain releif, pleaure, contentedness.
• GABA: inhibitor neurotransmitter.

1. An action (electrical) impulse is triggered, travelling to the axon terminals via vesicles.

2. Electrical impulse release at terminals as a neurotransmitter once the vesicles have fused with the membrane to release their contents.

3. Neurotransmitter crosses the synaptic cleft to the post-synaptic neurone.

4. If complementary receptors are present on the dendrites of the next neurone the neurotransmitter will bind and is accepted.

• 1. Nicotine: more dopamine as more impulses are triggered - more neurotransmitter made.
• 2. Cocaine: blocks reuptake channels so more dopamine present in the synapse.
• 3. Cannabis: binds to CBI receptors, blocking activity so there's more dopamine in the reward system.
• 4. Alcohol: depressant effect, increasing the action of GABA, that inhibits neurotransmitters, therefore, more neurotransmitters present.
  

Pros:

• Milner found pleasure centre in the brain of rats.
• Highly studied theory so very reliable and widely accepted.

Cons:

• Current tools cannot accurately see transmission.
• Animal brains are not the same as human brains so cannot be necessarily related.

Structure:

You need to know the internal and external structures.

Internal: hippocampus, hypothalamus, amygdala, cerebellum, pituitary gland.

External: frontal lobe, peritiel lobe, occipital lobe, temporal lobe.

As an explanation for aggressive behaviour:

• Prefrontal cortex controls emotions and decision making.
• Raine et al: showed NGRIs had differences in their prefrontal cortex.
• Charles Whitman had a small amygdala and uncharacteristically gunned students at his school dead.
• Phineas Gage: personality completely changed to be more aggressive after a rod through the brain.
• Downer: shows the amygdala is involved in aggression.

Charles Darwin proposed the theory of evolution that has since been used to describe why some of us may be aggressive.

The theory states that an advantageous gene will enable the species to survive and reproduce, therefore passing said gene on to offspring.

This works for aggression if, in the past, aggression has been advantageous to us as we were able to protect our young.

Therefore the most aggressive of the species were able to survive and pass on the aggressive gene to offspring until it becomes more frequent in the population.

Pros: renowned theory widely accepted. Lorenz found gulls were aggressive from birth.

Cons: this does not explain instances such as domestic violence, where there is no clear advantage, or why every person is not aggressive (why levels of aggression differ)

The Personality:

• Id: the 'I want' part of the personality.
• Ego: reasons between the superego and the id to make decisions.
• Superego: the conscience, battles with the 'I want' part every day.
• The Unconcious: repress bad experiences to here so they do not affect the person.
• Catharsis: release aggressive thoughts into the conscious.

Pros: strong and detailed explanation, concepts used today in therapy so very applicable, takes into account the individual (unlike most biological explanations).

Cons: doesn't explain how, just a description, people are still aggressive after catharsis which have been proven to not work.

Testosterone: a hormone linked with aggression, evidenced by the castration of mice making them less aggressive (testosteron is produced in the testes of males). Wagner et al.

Dabbs et al found that 10/11 prisoners had high levels of testosterone when a saliva swap was taken and anaylsed.

Barzmen et al studied 17 boys in a hospital and found the hormone cortisol directly correlated with aggression.

Case Studies:

Case studies are extremly specific to the person.

Damage to the brain may be affected by individual differences in case studies of braindamaged patients when it is assumed there are no individual differences.

Freud:

His view of the personality shows there can be development of individual differences, as each person will develop the personality to a different extent.

E.g. different mixes of the id, ego and superego can lead to a person percieving the same situation differently - if their 'I want' part overules the ego.

Gender:

Neurotransmitters: Jovanovic, 2008, shows womens brains have more serotonin receptors. We also contain different hormones (women have less testosterone and hormones releated to mensutration cycles that men do not e.g. FSH).

The Role of Evolution:

See slide 5, role of evolution and natural selection in aggression.

Opposingly, Rogoff & Mosier (2003) compared US families with Mayan Indian families and found the 'terrible two' stage of childhood did not exist, and where 61% of the childrens reactions were co-operative, 68% of the US childrens reactions were competitave.

The Role of Hormones:

The main hormones concerned with growth are pituitary growth hormone, thyroid hormone, the sex hormones testosterone and estrogen and the sex-gland-stimulating hormones.

CAT:

An alternative to x-rays, that can only look at hard bone structures, CAT scans are able to look at soft tissue from multiple angles to produce an image.

Pros: quick, not invasive. Cons: exposure to radiation, shows just structure and not function.

PET:

Injected with a radioactive material, such as glucose, that is traced in the brain and comes up as red showing activity and blue showing no activity.

Pros: reliable and valid, shows structure and function. Cons: invasive and too broad, expensive procedure, can only be done up to twice a year due to dangers involved.

fMRI:

Electromagnet traces changes in nuclei via blood flow in the brain, coloured areas show activity.

Pros: scientific, not invasive, high resolution image. Cons: claustrophobia, sometimes inaccurate due to movement sweking image, correlation not causation.

A: to find out if there is a genetic basis for schizophrenia.

P: Independent groups design using 62 schizophrenia sample, half male and half female.

• 24 MZ and 33 DZ twin pairs were identified.
• Mental health was then measured by hospital notes, questionaires, interviews, personality tests

F: In every category of SZs there was a significant difference between MZ ad DZ twins, with MZ twins being more liekly to share a similar diagnosis of mental illness. 21% of MZs had a healthy twin, 79% shared the illness. 55% of DZs were healthy whilst 45% shared the illness.

C: there is a genetic element to SZ but because MZ concordance was not 100% genetics can only predispose someone to getting the condition.

C: G: large sample, male and female. R: a repeat of previous studies = reliable. A: allow for screening for genetic disposition V: range of data collected. E: Yes, full debrief, no deception, consent.

A: Is there a genetic cause of schizophrenia?

P: 34 SZ patients, 33 controls.

• Tracked down Danish families through records, finding 463 relatives.
• Used mental health register to assess their mental health using 4 psychiatrists in a blind test.

F: 8.7% biological SZ concordance. 1.9% adoptive SZ concordance.

C: There is a genetic componant to SZ because biological families were more likely to share SZ that adoptive families. Kety went on to do more studies to confirm this point.

C: G: Only Danish, good sample with controls. R: repeatable as evidenced by Kety's own later experiments. A: genetic screening for SZ V: Yes concurrent validity with past studies. E: No consent for data to be used, kept annoynmous, potential stress.

Brain abnormalities in murderers indicated by positron emission tomography.

A: to see if there is a difference between murderers (NGRIs) and non-murderer brain scans.

P: 41 offenders, 39 male and 41 matches controls.

• PET scan, PPs kept medication free 2 weeks prior to the scan.

F: murderers showed less activity in the frontal lobe, the corpus callosum and an imbalance of activity between the two brain hemispheres

C:

• Prefrontal deficits might make someone impulsive and emotional.
• Deficits in the limbic system might make someone aggressive (includes amygdala).

C: G: Large sample and controls. R: PET is objective and reliable. A: early-intervention for those who have had damage to the brain. V: high internal, low ecological. E: consent, some harm due to invasive procedure, ethical concerns over conclousions of study.

A: Examining genetic and environmental effects on social aggression: A study of 6-year-old twins.

P: 234 twins from Quebec, longitudinal study: 44 MZ male, 50 MZ female, 41 DZ male, 32 MZ female and 67 DZ mixed.

• Teachers questionnaire about behaviour in physical and social aggression, scroes added from both to produce a single score.
• Children of the schools were then shown photos and told to circle for the best social and physical aggressive descriptors.

F: Chi2 showed no significant difference between the two teacher ratings. MZ ratings twice as high as DZ, both teacher and peer reatings suggested more genes than enviornment. 60:40 nearly each time.

C: Strong genetic element, through social aggression seems to be from the environment,

C: G: 88 pairs dropped out, only in Canada but large sample. R: questionnaires easily replicated, but lkanguage differences mean less reliable. A: could help reduce bullying V: high ecological, low internal  not 100% concordant though E: consent, though could create poor relationships.

What are the implications for society if aggression is found to be caused by nature not nurture?

Aggression:

• 2013 UN study created a World Homicide Map showing you are 25x more likely to be murdered in Brazil than in the UK.
• Can be explained by the amygdala, evolutionary theory, hormones, the environment you grow up in (SLT), your personality, brain structure, genetics such as the MAOA.

Implications for society:

• If violence is not part of human nature it would make the World Homicide Map make sense and mean that violence would decline as the world gets richer and healthier.
• Solution to violence would be to tackle poverty, sickness and corruption.
• If violence is part of human nature there may be screening or designer babies to try and remove the genes from children.
• Could lead to different court systems as they couldn't help themselves, it is a part of their nature.

A correlation to see if there is a relationship between finger quota and a self-rating of aggressive tendencies.

Long ring fingers shown to have more testosterone.

P: class questionaire on aggression and ringer finger measured.

Spearmans shown as 124 which was not significant, so we had to accept the null that there is no difference between finger quota and self-rating of aggressive tendencies.

G: No, same age and one classroom. R: No, though questionaires easily replicated. A: To pre-screening for aggression. V: No. E: all consented, no harm or deception.

• Milner found pleasure centre in the brain of rats.
• Raine et al: showed NGRIs had differences in their prefrontal cortex.
• Charles Whitman had a small amygdala and uncharacteristically gunned students at his school dead.
• Phineas Gage: personality completely changed to be more aggressive after a rod through the brain.
• Downer: shows the amygdala is involved in aggression.
• Charles Darwin proposed the theory of evolution that has since been used to describe why some of us may be aggressive.
• Lorenz found gulls were aggressive from birth.

• Dabbs et al found that 10/11 prisoners had high levels of testosterone when a saliva swap was taken and analysed.
• Barzemen et al studied 17 boys in a hospital and found the hormone cortisol directly correlated with aggression.
• Jovanovic, 2008, shows womens brains have more serotonin receptors.
• Rogoff & Mosier (2003) compared US families with Mayan Indian families and found the 'terrible two' stage of childhood did not exist, and where 61% of the children's reactions were co-operative, 68% of the US childrens reactions were competitive
• Gottesman and Shield (1966)
• Kety et al (1968)
• Brendgen et al (2005)
• Montelicco-Heino: castrated rats were less aggressive.