Psychology Biological Flashcards
Scanning Technology (MRI)
- 3D picture of brain structure
- MRI scanner uses a magnetic field and radio waves to map the activity of hydrogen molecules, which are present in different brain tissue to different degrees.
- The image can either be viewed as a slice of the brain from any angle, or it can be used to create a three-dimensional image of the brain.
pro:
+ non-invasive
+ minimal potential harm
+ high resolution
con:
- only indicates structure
- does not show what is happening
Scanning Technology (PET scan)
- observes metabolic processes in brain
- areas of high reactivity = brain activity
- patients given safe amount it FDG - goes through blood
pro
- produces multi colored image that show which part is active
- participants can preform tasks while scanning
con
- required injection of radioactive material
- will not cause harm but is invasive
- slow, poor resolution
Scanning Technology (fMRI)
- shows the structure of the brain
- shows brain activity and indicates which area of the brian is active
- measures changes in blood flow in the active brain
- most frequently used technologies in biopsychological research today.
- It tracks changes in blood flow and oxygen level as a measurement of neural activity.
- When a specific brain area is active, it uses more oxygen, and therefore the blood flow increases
pro
- high resolution
- activities can be perdformed
- easy to carry out
- non-invasive
- no radioactivity
- produces film over time
Maguire et al. (scanning technology)
Aim: aim of the study was to see whether the brains of London taxi drivers would be somehow different as a result of their exceptional knowledge of the city and the many hours that they spend behind the wheel navigating the streets of London.
Subjects:
- 16 right-handed male London taxi drivers
- 50 x right handed male who did not drive taxi
- participants had to have completed the “Knowledge” test and have their license for at least 1.5 years.
- The controls were taken from an MRI database. The sample included a range of ages so that age would not be a confounding variable.
Procedure:
- data from the MRI was measured using two different techniques: voxel-based morphometry (VBM) and pixel counting.
- Voxel-based morphology (VBM) was used in this study to measure the density of grey matter in the brain.
- Pixel counting consists of counting the pixels in the images provided by the MRI scans in order to calculate the area of the hippocampus.
Findings:
- First, pixel counting revealed that the posterior hippocampi of taxi drivers were significantly larger relative to those of control subjects and the anterior hippocampi were significantly smaller. - VBM showed that the volume of the right posterior hippocampi correlated with the amount of time spent as a taxi driver.
- No differences were observed in other parts of the brain.
Conclusion:
- Maguire argues that this demonstrates that the hippocampus may change in response to environmental demands.
How does this relate to localization of function? It appears that the posterior hippocampus is involved when previously learned spatial information is used, whereas the anterior hippocampal region may be more involved during the encoding of new environmental layouts.
Localization
the theory that specific parts of the brain is responsible for specific behavior and cognitive processes
Neuroplasticity
- brains ability to rearrange the connections between it’s neurons due to learning experience
- everytime we learn something, new trace in the brain is created (dentric branching)
- lack of stimulation to the area and discontinued behavior leads to neural pruning.
Draganski et al. (localization, neuroplasticity)
Aim: whether learning a new skill - in this case, juggling - would have an effect on the brains of participants.
participants:
- 24 volunteers between the ages of 20 and 24.
- There were 21 females and 3 males.
- All participants were non-jugglers at the start of the study.
- Each participant had an MRI scan at the start of the study to serve as a base rate for grey matter and brain structure.
Procedure:
- Participants were allocated to one of two conditions - the jugglers and the non-jugglers.
- Those that were in the juggling condition were taught a three-ball cascade juggling routine.
- They were asked to practice this routine and to notify the researchers when they had mastered it.
- At that point the jugglers had a second MRI scan.
- After the scan, they were told not to juggle anymore and then a third and final scan was carried out three months later.
- The non-juggling group served as a control group for the duration of the study.
Findings:
- They analysed the MRI scans, to determine if there was significant differences in neural density (grey matter) in the brains of jugglers vs. non-jugglers.
- From the baseline scans - taken before the study began - they found no significant regional differences in grey matter between the two conditions.
- However, at the end of the first part of the study, the jugglers showed a significantly larger amount of grey matter in the mid-temporal area in both hemispheres - an area associated with visual memory.
- Three months after the participants stopped juggling - when many were no longer able to carry out the routine - the amount of grey matter in these parts of the brain had decreased.
Conclusion:
- it appears that juggling relies more on visual memory
- shows plasticity of brain
Neurotransmitters
Chemical message to other neurons
- action potential across presynaptic neuron
- study using antagonistic drugs
Acetocholine:
- plays role in consodilation of memory (excitatory neurotransmitter)
- dentrict branching
- agonist
Scopolamine:
- inhibits memory formation
- inhibitory neurotransmitter
- neural pronings
- antagonist
Rogers and Kesner (neurotransmitters)
Aim: determine the role of acetylcholine in the formation of spatial memory.
Subjects:
- 30 rats acclimate to a Hebb Williams maze by placing food in one of the corners.
- Once the rats were familiar with the maze - and no longer were afraid of the environment - the experiment could begin.
Procedure:
- The rats were randomly allocated to one of two conditions.
- The rats were either injected with scopolamine or with a saline solution ten minutes before running the maze.
- Scopolamine blocks the acetylcholine receptor sites and thus inhibits any response.
- The saline solution was a placebo injection. This was done to make sure that the fact of getting an injection alone was not responsible for a change in memory.
- An injection could result in an increase in adrenaline which would be a confounding variable. The injections were made directly into the hippocampus.
Results:
- Encoding of memory was assessed by the average number of errors made on the first five trials of Day 1 compared to the last five trials of Day 1, whereas the average number of errors made on the first five trials of Day 2 compared to the last five trials of Day 1 was used to assess retrieval.
- The findings were that the scopolamine group took longer and made more mistakes in the learning of the maze - that is, there was a higher average number of mistakes made on the last five trials on Day 1.
- However, it did not appear to have an effect on retrieval of memories that had already been created. It appears that acetylcholine may play an important role in the consolidation of spatial memories.
Conclusion:
- acetylcholine plays important role in consadilation of spatial memory
Hormones
a set of chemical secreted by glands in the endocrine system, such as pituatary, thyroid and testes
although hotmones reach all parts of the body via the bloodstream, they only targer specific parts with compatable receptors
Cahill and McGaugh
aim : to study the role of emothion and hormones in on the creation of memories
procedure:
- 12 slides accompenied by varying stories
- first group: 1st story is boring, about women and her son who paid a visit to the father in the hospital, they witnessed staff in disaster preperation drill
- second group: boy was in a car accident, his feet were severed, brought to hospital, where his limbs were reattached stayed in hospital for weeks, then went home with his mom
- participants were asked questions, and had 3 options as answeres, A,B,C
- e.g. what job did the father have?
- in a follow up study participants in group two were injected with propanolol to prevent activation of amygldala, beta blocker
results:
- original: participants who heard traumatic story, shoed better recal of specific parts of the story, and details of slides
- follow up: participants with beta blocker did not do better than those who heard boring story
conclusion:
- amyglada plays significant role in creation ofmemory
- can be used in the treatment of PTSD
Pheromones
- A pheromone is a chemical substance produced and released into the environment by an animal affecting the behaviour or physiology of others of its own species. Although pheromones are known to play a significant role in signaling between members of the same species among animals to affect various behaviours, it is not clear that this is also true in humans
- Androstadienone [AND] is a human steroid that is present in male semen and sweat. It heightens sympathetic arousal, alters levels of cortisol, and promotes positive mood state in females. Androstadienone is also found to activate the hypothalamus in heterosexual females and homosexual males, but not in heterosexual males or homosexual females.
- Estratetraenol [EST] is the female equivalent of this steroid.
- One of the stumbling blocks to finding the role of a pheromone in humans is our lack of a functional vomeronasal organ [VNO] and an accessory olfactory bulb. Without the anatomical ability to detect the scent of a pheromone, it is unclear how a pheromone would affect human behaviour.
Genetics
genetic research
biologist do not simply argue that a gene causes a behavior
they recognise a gene-environment interactions
- this is called epigenetic
- it argues that genes must be expressed
- environmental factors such as stress, exercise or diet
- an individual can have the gene but not express it
- twin studies - same gene differenet expression
One of the ways in which genetic research is carried out is through a technique called “family studies.” In such studies, researchers look at the incidence of a behaviour over a number of generations. Usually, this is limited to three generations in most populations.
Weissman et al. (kindship and genetics)
Aim: to study the potential genetic nature of Major Depressive Disorder
subjects:
- longitudinal family study
- 161 grandchildren and their parents and grandparents to study the potential genetic nature of Major Depressive Disorder.
Procedure:
- The study took place over a twenty year period, looking at families at high and low risk for depression.
- The original sample of depressed patients (now, the grandparents) was selected from an outpatient clinic with a specialization in the treatment of mood disorders.
- The non-depressed participants were selected from the same local community.
- The original sample of parents and children were interviewed four times during this period.
- The children are now adults and have children of their own - allowing for study of the third generation.
- Data was collected from clinicians, blind to past diagnosis of depression or to data collected in previous interviews.
- researcher triangulation was used.
- Children were evaluated by two experienced clinicians - with one being a child psychiatrist and the other a psychologist. The inter-rater reliability of their diagnoses were 0.82 for MDD, 0.65 for anxiety disorders and 0.94 for alcohol dependency.
Findings:
- high rates of psychiatric disorders in the grandchildren with two generations of major depression.
- By 12-years-old, 59.2% of the grandchildren were already showing signs of a psychiatric disorder - most commonly anxiety disorders.
- Children had an increased risk of any disorder if depression was observed in both the grandparents and the parents, compared to children where their parents were not depressed. - In addition, the severity of a parent’s depression was correlated with an increased rate of a mood disorder in the children.
Evolutionary explanations of behaviour
- Evolutionary psychologists argue that our behaviours are the result of natural selection – that is, the behaviours that best served the human gene pool have been passed down from generation to generation.
- Since mating behaviours are an essential component of how behaviour is inherited, it should be no surprise that why we choose the partners that we do is a major focus of evolutionary psychologists.
- Wedekind studied what is known as the Major Histocompatibility Complex, a group of genes that play an important role in the immune system.
- MHC genes make molecules that enable the immune system to recognize pathogens; in general, the more diverse the MHC genes of the parents the stronger the immune system of the offspring. MHC genes are expressed co-dominantly – that is, we inherit the MHC alleles from both of our parents and they are expressed equally.
- Evolutionary psychologists argue that our “smell” is a sign of our MHC. Wedekind wanted to see if women are attracted to a man because of his MHC. He did this in his famous “Smelly T-Shirt Study.”
