Bloa Studies

Aim: Test effects of glucocotides on memory

Process: Independent samples. One set of rats taken away from mother (handled) and other set (control) wasn't. Handled rats secreted more glucocotides than control + later in life showed higher basal levels. These effects then were tested by putting rats into pool of milky water with platform.

Results: Handled rats too a longer route to get to platform. Glucocotides can cause hippocampal cell loss = pronounced spatial memory loss.

Eval.: Was able to establish cause-effect, supported by studies on alzheimer's and dementia. Does not explain exact process

Aim: Investigate effects of environment on neuronal development in cerebral cortex.

Process: Enriched vs. impoverished environment 10-12 rats in E with stimuli and toys. I rats in cages and with no toys. 30-60 days -> killed and brains studied.

Result: Thicker and heavier cortex of E vs. I.

Eval.: Study challenged belief that brain cannot change weight. Cause effect established (lab). Replicable. Animals used- can it be generalised? Ethics-boredom + killing. Technically, ethical issues are outweighed byinfo gained for brain plasticity. Further research done that supports the findings.

Aim: Investigate role of oxytocin after breaches of trust.

Process: Participants played trust game. P1 receives money and decides to share or not with trustee (P2). If money is shared, it is tripled. Then P2 chooses to share or not. fMRI scans used on 49 participants who received either a placebo or oxytocin nasal spray. 50% of the time the player's trust was broken.

Result: Placebo group showed less trust and invested less. Oxytocin group continued to invest similar rates (even when trust broken). fMRI showed decreased response in amygdala (oxytocin receptor) and caudate nucleus (learning, memory, trust)

Eval.: Oxytocin explains why people are able to forgive. Scan is only mapping activity does not show process. Does not reflect real life/lacks ecological validity.

Aim: To see how sensory deprivation affects the brain

Process: Researchers studied group of Buddhist monks who were on a 72hr pilgrimage to a holy mountain (Japan). They did not consume food/water + did not speak. Weather was cold. After 48hrs they began to hallucinate. Blood samples were taken before and after hallucinations.

Results: Serotonin levels increased which activated hypothalamus and frontal cortex resulting in hallucinations.

Concl.: Sensory deprivation triggered release of serotonin

Eval.: All men and not sexually active and Japanese- lacks generalisability. Observation- no control therefore may be confounding variables. Ecological validity.

Aim: To determine the role of acetylcholine on memory (and learning).

Process: Rats trained to go through maze and received food at end. After learning, rats were split into 3 groups- 1 injected with acetyl. (receptor site) blocker. 2 injected with acetyl. enhancers (stops synapse from returning to resting state). 3 control.

Result: 2 was better at completing maze and finding food.

Concl.: More acetyl. more memory.

Eval.: Cause- effect due to lab. Generalisability to humans? Ethics- using animals.

Aim: Measure volume of hippocampus based on theory that prolonged stress may reduce the volume of hippocampus due to cortisol.

Process: MRI scans of brains of participants who were veteran and female adults who were victims of childhood sexual abuse (some with PTSD).

Result: Those with short term memory deficits were scanned and PTSD patients found to have smaller hippocampi.

Concl.: Correlation found between number of years of abuse and memory problems and hippocampal volume.

Eval.: V. small sample question of reliability- smaller hippocampus could be due to other factors. Has been replicated, well controlled and MRIs are safe.

Background: HM fell of bike at 9 resulted in brain damage. Had epileptic seizures and drugs did not control them.

Method: at 27, HM had a brain surgery to control epilepsy and stop seizures. Removed tissue from temporal lobe including hippocampus. HM was studied for 40 years.

Results: After operation, HM had anteretrograde amnesia- unable to create new episodic memories but could learn procedural memories. Childhood memories stayed.

Concl.: Hippocampus is needed to transfer memories into long term and brain has many memory systems meaning that memory is more complex than anticipated.

Corkin- took MRI scans and found parts of temporal lobe (incl. hippocampus and amygdala) were missing but damage not as great as anticipated)

Eval.: Contributed greatly to research. In-depth. Studied something that could not be ethically done in a lab. Small sample- lacks population validity, cannot be generalised. Cannot be replicated- rare phenomenon and lacks reliability. Case study- may be biased to researcher. Ethics- HM was not able to remember being studied for 40 yrs.

Process: 5-Htt gene influences level of serotonin (controls mood). Researchers compared participants with normal 5-HTT gene and participants with mutation of it that made it shorter.

Result: Found that mutation carriers + people who have experienced many stressful events were more likely to become depressed than those who experienced stress with the longer allele. 5-HTT may indicate vulnerability to to depression from stress

Conl.: Being genetically predispositioned to depression does not mean that that person will develop depression.

Eval.: Results from genetic tests may result in personal stress someone may choose not to have children. Not all people with gene have depression- cannot be attributed to gene + people without gene mutation also have depression. Correlation- not cause-effect.

Aim: investigate if disgust sensitivity in the first trimester of pregnancy is elevated.

Process: web-based survey was completed by 691 women on pregnancy websites. Mean age 28. 16 point level for nausea in 8 different areas (food, contact with animals, body products, dead animals, hygiene, contact with toilets)

Results: disgust sensitivity related to food and body products was higher of those in 1st trimester vs 2nd and 3rd. Particularly food. Food-borne diseases are v dangerous during 1st trimester and therefore food sensitivity is heightened.

Concl.: Nausea and vomiting evolved to limit likelihood that pregnant woman will digest dangerous foods.

Eval.: Questionnaires (self-report) may not be reliable (no control). Findings supported by other studies. Large sample. Cannot be attributed purely to evaluation- environment. Quasi experiment- no iv manipulation but has ecological validity.

Process: Recruited MZ and DZ twins. Volunteered and males raised together. Sexual orientation determined through being asked directly or asking the homosexual participant. Questionnaires assessing the level of childhood gender nonconformity. (phenomenon which prepubescent children do not conform to their expected gender patterns or identify with opposite sex).

Result: 52% of MZ twins and 22% of DZ both identify as homosexual. Evidence that the more close the genetic link, the more likely that both are to exhibit gay/straight identities. Supports genetic link for homosexual behaviour.

Eval.: sample- non random- gay magazine so ascertainment bias. Skewed data- one twin was already gay. Self-reported data- no way of checking. Bias.