Biological approach - psychology

Themes and studies desriptions

Techniques used to study the brain (MRI and fMRI)

MRI - Magurie(2000)

MRI (Magnetic Resonance Imaging)

Two magnets: first magnet align the hydrogen atoms in the body and second magent sends radio waves that disturb this aligment and when hydrogen atoms return to relaxed state computer captures this information and creates visual images of brain structure that can be futhered analysed by researchers (by voxel-based morphemetry (grey matter density) and pixel counting (area))

Can detect sutructural changes ( but also tumors).

Maguire (2000):

Aim: To investigate the structural differences in the brain of London taxi driver /or to investigates the brain structures associated with spatial navigation memory (depending on the question asked)

Procedure: 16 right handed male London taxi drivers (had licence for at least 1.5 years). They were put in MRI scanner and the scan of their brain was analysed (voxel based morphemetry and pixel counting) and compared with 50 pre-existing MRI scans of healthy right-handed males).

Results: Taxi drivers - greater area and grey matter density in posterior hippocampal region BUT less density and smaller area of anterior hippocapal region compared to non-taxi drivers.

Conclusion:

Posterior - associated with using pre- existing spatial navigation memory.

Anterior - associated with creation of new spatial navigation memory.

Limitations:

• quasi-experiment no cause and relationship can be established - findings are correlational

• participants may ealier in life developed those areas of brain and that is why they chose to become taxi drivers

• MRI causes stress and discomfort especially to the older participants

Strengths:

• empirical evidence

• biological explanation for behaviour

• localisation of functions

Strengths of MRI:

• High resolution image

• non-invasive technique

Limitations:

• loud banging noises - uncomfortable and may cause stress

• prone to errors cause by distrurbances like movement, temperature

• ethics - may reveal tumors or other diseases

fMRI (functional Magnetic Resonance Imaging):

• is a neuroimaging technique that measures brain activity by detecting changes in blood flow, providing real-time data on brain function.

• it is based on BOLD (Blood Oxygen Level Dependent) signal because oxygenated and deoxygenated blood have different magnetic properties. fMRI enables researchers to observe brain activity and correlate it with cognitive tasks.

• It is based on the assumption that regions more active require more oxygenated blood for energy. This method helps understand how different brain areas engage during various mental processes.

• color-coded scans indicating intensity of oxygentaed blood flow

Strengths:

• It provide higly detailed information regarding brains activity

• is non-invasive

• helps to link biological mechanisms with psychological processes

Limitations:

• It has 5-seconds dely between the neural activity and the fMRI measurement, which can complicate interpretation of data.

• it is indirect method for mesuring neurtrasmitters effect or hormons

  Study: Fisher (2005) or Sharot (2007)

  Fisher(2005)

  Aim: to investigate the role of dopamine in romantic love

  Procedure: 17 participants who described being “in love”. Undergo functional MRI techniques to measure brain activity linked to romantic feelings. During the scanning were shown a picture of their loved one followed by distractng task and then picture of a person non-romatically connected. The scans were analysed.

  Results: Activation in the ventral tegmental area and caudate nucleus was observed while participant was looking at the picture of their loved ones. Those areas are associated with dopamine release. So if more oxygenated blood flow there therefore more dopamine release connected to reward, motivation and addiction.

• Conclusion: fMRI helped show that romatic love is associated with activation of domapine regions of the brain suggesting that people can become “addicted” to love.

  Limitation:

• findings are correlational - indirect measurement of dopamine release

Localisation of functions

The idea that specific areas of the brain are responsible for particular mental processes, such as memory or emotion.

Maguire (2000) and Draganski demonstrated how brain structures are associated with specific cognitive tasks, highlighting the concept of localization.

Neuroplasticity

The brain's ability to reorganize itself by forming new neural connections throughout life. It enables adaptation and recovery from injury, as well as learning and memory.

Maguire (2000) but better use Draganski (2004)

Draganski (2004) investigated the effects of learning a new skill on brain structure, showing that physical changes occur in response to experience, supporting the concept of neuroplasticity.

Participants: self selected sample of 24 adults (no existing experience with juggling)

Procedure: Randomly allocated to two condition either juggler or non-jugglers. Procedure involved teaching participants a juggling routine and then waiting for them to learn the skill and then asking them to stop juggling at all. Three MRI scans were done on fixed intervals: before training, after learning, and after stopping (3 months later)

Findings: MRI scans showed that there was no difference between brain structures at the beggining.

Then after learning the skill juggling group MRI scans showed an increase of grey matter in mid-temporal cortex - associated with visual memory, coordination and movemnt.

After 3 months of not practicing the skill there was a decrese in grey matter in mid-temporal cortex indicating neural prunning and suggesting that learning new skills leads to structural brain changes. But there still was greater amount in contrast to the begining.

Conclusion: Grey matter icreased in specific brain regions as participants gain and learned new skill (neuroplasticity in response to environmental demands). As the skill is not needed (stop juggling) the grey matter decrease (neural prunning).

Neural prunning is the process by which unused neural connections are eliminated, aiding the brain's efficiency.

Strengths:

• high internal validity - baseline measurments that are absent in Maguire study

• useful application of findings - possible therapies for degenerative brain conditions - Alzheimer.

Limitations:

• self - selecting sample - not representative

• jugglers participants were not in controlled environment when learning and stopping juggling. So some might have over-practiced, underpracticed which would mean that neural growth and prunning was due to other factors.

Hormones (oxytocin and testosterone)

Zak (2009) and Kosfeld (2005) investigated the role of oxytocin and testosterone in social behaviors. Oxytocin, often referred to as the "cuddle hormone," is linked to social bonding and trust, while testosterone is associated with aggression and competitive behavior. Both hormones play significant roles in influencing psychological processes.

Zak - testosterone and males generosity

Procedure: 25 males exposed to either textosterone gel or placebo (increase in hormone measured by blood tests) . After 1 day played an Ultimatum game - decision making game deciding how to split and donating money with the other player. If the offer was too low, it could be rejected and neither received the money.

Results: when on testosterone participants offered 27 % less money compared to placebo. And if received low sum rejected more often and the money was lost. Testoserone decrease generosity maybe due to status-seeking or dominance motivation.

Conclusion:

Testosterone influence social-decison making by redusing prosocial behaviour and increasing selfishness and competetiveness in males.

Kosfeld (2005)

Role of oxytocin in interpersonal behaviour and in promoting prosocial behavior and trust.

Male participants randomly allocated to euther oxytocin or placebo group (internasal injections). Played a trust game in which either assigned a role of “investor” or a “trustee”. Investors could give (0,2.4.8,12) monetary units to a trustee and the amount was tripled. Trustee could return any amount of money but without multiplying the sum. Also palyed risk game (the same but all participants were investors and played agaist computer)

Neurotrasmitters

Chemical messengers that transmit signals across synapses between neurons, influencing various psychological functions and behaviors.

Serotonin - Caspi et al (2003) - Link between 5-HTT gene and depression in response to stessful life events)

Caspi:

• self recalled data of stressful life events ( 21st - 26th birthdays)

• Then intervew to asses the depression episodes

• and correlational analysis between alleles length, perceived stress and developing a depression

Dopamine - Fisher (2005) - dopamine in romantic love.

Genes and behaviour

Caspi (2003) 5-HTT gene and depression

Twin studies

Monozygotic - share 100% of DNA

Dizygotic - share 50 % of DNA

McGuffin (1996)

whether exeriencing a depressive episode increases the likelihood of major depression in twin.

177 twins one -proband had diagnosed major depression.

Procedure: diagnostic assessments and interviews to gather info on depression history and symptoms

Conducted blindly.

Self reported psychiatric interviews

Hospital data

Resreachers calculated correlations in liability and corconance rate which is likelihood of the twin also developing depression based on the presence of major depression in the proband.

MZ twins - 46% concordance rate for major depression

DZ twins 20 % corcondance rate

Shorter depressive episodes (less than 13 months) were more stronly associated with other twon also being depressed

Conclusion: There is a strong genetic component to major depressive disorder

Shared family environment does not appear to play a significant role

Shorter depressive episodes in one twin may indicate higher genetic vulnerability

Evolutionary explanation fo partner preference - based on anisogamy (eggs are costly - females more selective, sperm is cheap)

The evolutionary explanation for partner preference suggests that due to anisogamy, where females produce fewer, more costly eggs and males produce numerous, less costly sperm, females tend to be more selective in mate choice to ensure the best genetic quality and resource provision for their offspring.

Buss 1989) conducted a study revealing that women prioritize financial stability and ambition in partners, while men value youth and physical attractiveness.

participants : Around 10 000 people from 33 countries covering 37 different coultures.

age : 16-28

Procedure: participants rated 18 characteristics on a scale of 0 - undesirable to 3 (must be) and also ranked 13 traits in order of importance

Findings:

females (36 out of 37 cutures) rated good finantial prospects as more important than males did.

Males preferred younger partners females preferred older partners- reproductive strategies

Moderate support for chastity (czystość) preference - 62% of males valued it more than females (males cannot know (withot DNA testing or obvious differences) that the child is his)

Excitatory neurotransmitter

Chemical substances that promote the firing of neurons, increasing the likelihood of the transmission of an action potential between neurons.

Glutamate is the most common excitatory neurotransmitter in the brain, playing a key role in learning and memory but also can contribute to neurotoxicity in excessive amounts.

Kraal (2020) investigated dietary glutamate in chronic pain.

Procedure: analysis of previuos researches and studies on glutamate's effects on pain perception. Findings suggested that high dietary glutamate may influence chronic pain conditions and further study is needed to establish direct causal relationships.