Biological Approach

methodology studies

HM + Bremner

methodology key words (6)

case study, brain scan, MRI, VBM, pixel counting, PET

case study

longitudinal research of a particular person or event in order to gain information about how the brain affects behavior- commonly used before technological advancements in neuroscience

brain scans

a more modern way of studying brain and behavior as technology has developed given psychologists more nuanced understanding

MRIs

magnetic resonance imaging- produces a 3D map of brain structure using a magnetic field and radio waves to map hydrogen molecules that are present in brain tissues showing the density of different areas of the brain- can be viewed as a slice or full 3D image

pixel counting

method used to calculate the areas of brain areas using an MRI scan

VBM

voxel-based morphometry- method used to determine the volume of brain areas using an MRI scan

PET scans

positron emission topography- observes metabolic brain processes by detecting gamma rays emitted indirectly by a small, non-harmful radioactive trace which is introduced to the bloodstream by a modified glucose (FDG) molecule which travels to the brain; the most active areas will use the most glucose so will emit the most radioactivity. Produces a multicolored image with the activity being indicated by the colors

HM

A- to investigate the function of the brain using a case study of someone with brain damage

P- HM had his hippocampus removed in a lobotomy procedure with the aim of curing his epileptic seizures, he was observed regularly at his home through the following 50 years before his death, one famous test includes the star test in which he had to repeatedly trace a star whilst only seeing his hand in the mirror in order to test his procedural memory

F- was able to retain information in STM shown through retention of short convos, improved at star task through attempts but didn’t remember previous attempts

C- different areas of the brain are responsible for different types of memory, case studies can be effectively used to study the brain and behavior

HM Carat

case study allowed for otherwise unattainable information to be gained due to it being unethical to reproduce

high ecological validity and mundane realism due to him being studied in his own home increases internal validity

longitudinal means cause and effect can be more confidently established

researcher triangulation decreases effects of researcher bias increasing internal validity

results cannot be ethically generalized or applied because it could be only for HM

Bremner

A: to investigate the effects of childhood sexual abuse and PTSD on the structure of the brain

P: 33 women- 10 w/ sa and PTSD, 12w/ sa no PTSD and 11 w/ neither, MRI scan to see volume of hippocampus using VBM, PET scan to view function of hippocampus during verbal declarative memory task

F: women suffering from PTSD had 16% smaller hippocampus than women w/o and 19% smaller than ppl w/o sa, as well as showing less function during task

C: neural pruning occurs from continuous return to extreme trauma and stress, leading to hippocampal atrophy, MRI can be used to study brain structure and PET can be used to study brain function

Bremner CARAT

cause/effect can be established due to lab conditions decreasing extraneous variables and brain scans eliminating demand characteristics and social desirability bias

lacks ecological validity and mundane realism- brain function may occur differently when occurring in a PET machine

retrospective- could be other extraneous variables leading to this atrophy

Localisation studies

HM + Maguire

Localisation key words (4)

localisation, equipotential theory, monolithic theory of memory, hippocampus

Maguire

A: to investigate the brain structure of London taxi drivers- specifically hippocampi due to time spent navigating routes

P: MRI scans of 16 right handed male taxi drivers who had completed the knowledge test and had their license for at least a year where compared to 50 non-taxi drivers using VBM and pixel counting

F: posterior hippocampi were significantly larger in taxi drivers, the volume was correlated with the time spent as a taxi driver

C: the posterior hippocampi is used for navigation and remembering routes causing neural branching in this area for taxi drivers

Maguire CARAT

brain scans were looked at single blindedly decreasing impacts of researcher bias and increasing internal validity

MRI reduces chance of demand characteristics and social desirability bias

retrospective and naturally occurring variable which cant be manipulated meaning cause/effect can’t be established only correlation- differences could be due to other extraneous variables (low internal and external validity)

localisation

the theory that brain functions have specific areas in the brain which are responsible for them

equipotential theory

the theory that the responsibility for brain functions is shared between different areas of the brain

hippocampus

an area of the brain this is usually linked with memory

monolithic theory of memory

the theory that all memory is localized to once specific area as one function

neuroplasticity studies

Rosenzweig, Bennett and Diamond and Bremner

Neuroplasticity key terms

neuroplasticity, dendritic branching, aborisation, long term potentiation, dendritic pruning, hippocampal atrophy

neuroplasticity

the brains ability to alter its structure in response to environmental changes

dendritic branching

the process of new dendrites sprouting due to repeated stimulation- occurs due to an enriching/stimulating environment or repeated practice of a particular task

aborisation

occurs after lots of branching when dendrites form tree like structures

long term potentiation

how branching happens- when a neuron is stimulated an action potential is created which travels down the axon, repeated stimulation causes gene expression

dendritic pruning

dendrites are pruned during times of high stress or due to lack of use

hippocampal atrophy

a possible result of dendritic pruning in the hippocampus- it becomes smaller

Rosenzweig, Bennett and Diamond

A- to investigate how enriching environment and deprivation can affect the brain structure of rats

P- rats were placed in either an enriching environment with other rats, stimulating toys and food choices or an environment of deprivation alone, with no toys and basic food, they were killed after 30 or 60 says and their brain structure was examine

F- rats in the enriching environments had thicker cortexes than those in the environments of deprivation, this doubled in 30 days compared to 60 days

C- stimulation of the brain can lead to new neural pathways being formed and an increase in neural density

Rosenzweig, Bennett and Diamond Carat

highly controlled lab experiment means cause/effect relationship can be established- high internal validity, may not be generalizable to humans due to differences between rats and humans, leaves questions answered eg: what about the enriching environments caused the branching

Animal Models

when research cannot be conducted on humans they are conducted on animals

why are animal models used (3)

the procedures are too unethical to carry out on humans

the effects can be easier studies across generations due to shorter life spans

animal conditions are easier to control (no demand characteristics etc.)

animal models positives (6)

we can compare them to human experiments on the same topic to determine their value

lack of demand characteristics and observer effect strengthening cause/ effect relationship

currently the only way to study some theories until new tech is developed

legislation such as the 1986 Animal Act in the UK makes it more ethical

use of the 3 Rs also increases ethics- reduce number of animals, replace the technique whenever possible and refine the technique to cause the least harm possible

utilitarian view of ethics says its for the greater good of the psychological field

animal models negatives

lack of generalizability to humans- only really valuable if there is other research confirming the effect in humans. just because some behaviors are similar this is only a correlation and we cannot assume it will be the same with all behavior

suffering of animals being undetectable doe snot mean it’s not real- why are practices too unethical for humans ethical for animals?

animal brains do not have the same nuance as human brains- they are not as effected by social and cultural factors leaving results lacking nuance

studies + theory for value of animal models in brain and behavior

Rosenzweig, Bennett and Diamond and Bremner- neuroplasticity

ethical animal considerations in Rosenzweig, Bennett and Diamond

very little value placed on the lives of the rats- killed before researchers even knew if the results would be valuable

studies + theory for values of animal models in genetics and behavior

Cases and Caspi- genetic predispositions

Cases

A- to investigate the genetic origins of aggression in mice

P- mice were genetically modified to have an enzyme that breaks down norepinephrine and serotonin called MAOA deleted, the researchers then observed these mice’s behavior when they were placed in a cage of control mice and when alone

F- the mice ran frantically, shook violently and bit the experimenters, when placed in the cage with the other mouse they adopted a threatening hunched position and participated in aggressive behavior

C- for mice behaviors can be based on genetic factors, when human males lack the same enzyme their aggressive behaviors may be attributed to this

Cases CARAT

highly controlled so cause/effect can be established and high internal validity- level of control not possible with humans

can’t necessarily be generalized to humans- what about social factors?

undue harm caused to mice- clearly distressed

Caspi

A- to examine the role of 5-HTT in depression

P- 847 kiwis assessed longitudinally from ages 21-26, divided into 3 groups based onto their alleles of the gene (short/long), periodically filled in stressful life event questionnaire and assessed for depression

F- people with short alleles were more likely to develop depressive behaviors in response to stressful life events

C- the gene gives humans a genetic predisposition to depression

Caspi CARAT

self report- danger of self report effect and introspection illusion and possibility of bidirectional ambiguity- those depressed more likely to present stressful life events (not actually predisposition)

external validity- only kiwis, culture may hinder or encourage the development of of depressive behaviors

longitudinal makes cause and effect easier to establish and enhances predictive validity

what does the comparison of cases and caspi say about the value of animal models

predisposition in humans and not animals- whilst the animal model can tell us the behaviors can be genetic it lacks the nuances of social factors and predispositions

value of animal models in hormones studies

Meaney and Newcomer (cortisol)

Meaney

A- to investigate the effect of cortisol on the memory of rats

P- rats separated from their mothers for 15 minutes everyday, some were brushed for those 15 minutes- imitating being groomed by their mothers whilst the other were not (this would raise levels of cortisol), two years later the rats were put into a pool of milky water with a platform, the researchers tracked the route the the rats took to escape based on memory of past attempts to escape

F- the rats who were not groomed took a more circuitous route to escape

C- the heightened levels of cortisol in their early lives impacted their memory- for rats high levels of cortisol can have long term negative impacts

Meaney CARAT

longitudinal and prospective high predictive validity and internal validity

hard to control extraneous variables such as how much grooming rats received outside of 15 mins decreasing internal validity

assumed to be generalizable to humans- possibly not true

undue stress or harm caused to rats

cortisol wasn’t directly measured could actually be other factors eg: neuroplasticity