BLOA Studies Flashcards
Martinez and Kezner (1991)
1991
Aim: to investigate the role of acetylcholine in memory formation.
Method: used rats in a experimental study. They were trained to run a maze and then divided into three groups.
Group 1- injection with scopolamine- blocks acetylcholine receptor sites, reducing available acetylcholine.
Group 2- injection physostigmine-blocks production of cholinesterase which cleans up acetylcholine from the synapses, leading to more available acetylcholine.
Group 3- a control group received no injections.
Findings: group 1 had problems finding their way through the maze and made more mistakes. Group 2 ran quickly through the maze, quicker than the control group and made few mistakes
Conclusion:
shows acetylcholine is important memory because the rats showed different memory capacity depending on acetylcholine level.
Evaluation:
A controlled lab experiment= can be concluded that the level of acetylcholine is one factor that affects memory (control group makes it possible to identify a cause-effect relationship) but neurobiology of memory is very complex. Questionable to what extent the finding can be generalised to humans.
Use: this study shows that the neurotransmitter acetylcholine affects the human behaviour of memory by causing an increase in memory functions with higher amounts of acetylcholine compared to lower levels of acetylcholine, which decreases memory functioning.
Berridge and Kringelnach (2009)
2009
investigated the effects of dopamine in pleasure seeking.
¬ fMRI scans were used to study the brain areas involved in the subjective experience of pleasure. They found that the orbitofrontal cortex was active when people reported feeling pleasure.
¬ The researchers concluded that dopamine and the nucleus accumbens is maybe involved in pleasure seeking. This could explain addictive behaviour.
¬ The orbitofrontal cortex and natural opiods are perhaps linked to the subjective experience of pleasure.
Fisher (2004)
2004
investigated dopamine in “addiction to love”
This is an evolutionary explanation of behaviour. “Being in love” had similarities with “being addicted” according to Fisher.
¬ Dopamine increases desire and reward by triggering the same emotional rush of pleasure when you see or think of the loved one as if you were taking a drug like cocaine.
¬ Dopamine can explain the highs of romantic passion (high levels of dopamine) and the lows of rejection (low levels of dopamine)
Avery et al (2001)
2001
Provides indirect evidence for the role of melatonin in SAD.
Method:
Randomly assigned 95 SAD patients to 3 groups.
1. Bright-light therapy
2. Dawn simulation
3. Placebo
A structured interview was used to provide a depression rating specific to SAD
Results:
Group 1 & 3 showed less improvement in symptoms and more side effects than the dawn stimulation group. Group 3 complained of more insomnia than the other groups at four weeks.
Conclusions:
SAD symptoms are related to shifts in sleep patterns caused by a lack of daylight at the normal waking time.
Bright-light therapy and dawn simulation helped to realign sleep patterns with the people lifestyles.
This is probably because these therapies help to inhibit melatonin secretion at appropriate times.
BUT the study didn’t look at melatonin levels.
Braumgartner et al (2008)
Aim: to investigate the role of oxytocin in trust.
Method: 49 participants. They played a trust game used by economists and neuroscientists to study social interaction. The investor (player 1) receives a sum of money and decides whether to keep it or share it with a “trustee” (player 2). The sum is triples if shared. Then player 2 must decide if the sum should be shared (trust) or kept (violation of trust).
fMRI scans were carried out on the participants and they received either oxytocin or a placebo via nasal spray. Participants played again difference trustees in trust games and against a computer in a risk game, in 50% of these their trust was broken. They also received feedback from the experimenters on this during the games.
Results: placebo group likely to show less thrust after feedback on betrayal, invested less.
Oxytocin group continued to invest at similar rates after feedback on a breach of trust.
Evaluation: oxytocin could explain why people are able to restore trust and forgive in long term relationships. Giving oxytocin like this in an experiment may not reflect natural physiological process. Function of oxytocin is very complex and its too simplistic to say its simply the ‘trust hormone’.
Maguire et al (2000)
Aim: to investigate whether changes could be detected in the brains of London taxi drivers, who have extensive experience in spatial navigation. Also to further investigate the role of the hippocampus in spatial memory.
Method: the participants where 16 healthy, right-handed, male taxi drivers, with an age range of 32-62 years and a range of experience, all had been London taxi driver for at least a 1 ½ years. The researchers used structural MRI scans of the taxi drivers and compared them to the scans of a control subjects, which were not participants but existing scans of 50 healthy, right-handed males who didn’t drive taxis.
Results: posterior hippocampi of the taxi drivers were much larger compared to those of the control subjects, the anterior hippocampal region was larger in the control subjects than in the taxi drivers. The hippocampal volume correlated with the amount of time spent as a taxi driver.
They concluded that there has most likely been a redistribution of grey matter in the hippocampi as a result of intense development and use of spatial memory skills required to remember the routes.
Evaluation:
+
Use of technology= no researcher bias/demand characteristics.
-
Natural experiment difficult to make conclusions as any differences found between two groups may not have occurred because of the independent variable-Cant ID cause and effect relationship.
Participants only male/right-handed.
Use: research suggests that the continuous use of an environmental stimulus leads to neuroplasticity when the use of one area of the brain is increased, this area increases in volume. With the taxi drivers, the environmental factor of an increased use of spatial memory, which is localised to the hippocampus, lead to an increase in the volume of the hippocampus.
Rosenzweig et al (1972)
1972
Aim: to investigate whether environmental factors, an enriched of depreived environment, effect neuroplasticity. In particular, the development of neurons in the cerebral cortex.
Method: the participants were rats,placed in an enriched environment or in an impoverished environment (IV=type of environment).
EE: 10-12 rats in a cage provided with different stimulus objects to explore and play with. Also received maze training.
IE: eact rate in an individual acge , in isolation and no stimulation.
The rate were exposed to their environments for 30-60 days before the were euthanized so their brains could be studied. DV=weight of brain.
Findings: the anatomy of the brains of the rats in the EE and IE differed. Rats from the EE had thicker cortex and heavier frontal lobe (associated with thinking, decision making and planning), compared to the rats in the IE.
The rats from the EE had also developed more acetylcholine receptors in the cerebral cortex.
Evaluation:
+
very controlled lab experiment possible to establish cause-effect relationship.
-
lacks ecological validity as the findings can’t be generalised to humans because the brains and environmental inputs differ between humans and animals such as rats.
Curtis et al (2004)
2004
Aim: to investigate whether there were patterns in people’s disgust responses.
Method: 77000 people from 165 countries participated in an online survey. They were shown 20 images, for each they were asked to rank their level of disgust. Among the 20 images were 7 pairs in which one was infectious or potentially harmful to the immune system and the other was visually similar but not infectious.
Results: disgust reaction was most strongly elicited for the images that could be harmful to the immune system. Disgust reaction decreased with age, disgust reactions were higher in young people than in older people, women had high disgust reactions then men.
Evaluation:
+
big sample and range of nationalities good generalisability-if they want to see how disgust has evolved, it has to be seen universally which they did.
-
ethics involves in showing people repulsive images.
Protection of participants from physical and psychological harm. (aim is to break ethical harm as they want to stimulate disgust).
However, done in an ethical way- on a computer you can quickly and easily get rid of the image.
Fessler et al (2005)
2005
Aim: to investigate their prediction that disgust sensitivity in the first trimester of pregnancy was heightened.
Method: 691 pregnant women with a mean age of 28.1 years completed a web-based survey, they were offered no compensation. In the survey they were asked to indicate their current level of nausea using a 16-point scale. They then answered questions in order to test their disgust sensitivity in 8 different areas.
->food, contact with animals, body products, dead animals, hygiene, contact with toilets.
Findings: pregnant women in the first trimester had higher disgust sensitivity to food and body products than women in their second and third trimester.
Disgust sensitivity level was particularly heightened in relation to food, which is what the researchers predicted.
->food borne illnesses are dangerous to women in the first trimester, disgust sensitivity level was predicted to be high.
Results may suggest that nausea and vomiting are an evolved behaviour because they decrease the rick women will eat dangerous food.
Evaluation:
+
findings supported by other studies (Curtis et al 2004) so although not big but significant in this study, other research points in the same direction which makes the finding more reliable.
-
data collected through questionnaires. Self-reports may not be reliable. Not an effective way of measuring disgust->more reliable to confront participants with real disgust-eliciting objects.
Bouchard et al (1990)
1990
Aim: to determine how much of intelligence is attributed to genetics or the environment.
Method: longitudinal study over 11 years. Over 100 sets of self-selected MZT ( monozygotic identical twins raised together) and DZT(dizygotic fraternal twins raised together) from around the world (cross cultural study) were raised together and apart. Researchers gave them approximately 50 hours of psychological and physiological testing. Tests included the WAIS and an adapted Raven test.
Results: similarity rates between MZTs raised apart were approximately 76%. Bouchard determined a heritability estimate of 70% of intelligence attributed to genetics, and 30% to other factors.
Evaluation:
+
much research has supported these findings making them reliable.
Large sample making the study more externally valid.
-
Correlation data can’t establish cause-effect.
No control for the effect of environmental variables which effects accurate estimations of genetic contribution to intelligence.
Whalstein (1997)
1997
Aim: to investigate how socio-economic status affects IQ. Wanted to show higher socio-economic status improves IQ.
Method: transferred an infant from a low socio-economic status to a home where the parents have a higher socio-economic status.
Findings: IQ increased 12-16 points, suggesting that environment has a lot to do with intelligence.
Conclusion: strong interaction between genes and the environment to produce intelligence level.
-Strong interaction between genes and the environment to produce intelligence level.
Scarr and Weinberg (1997)
1997
Aim: to determine the contribution of environmental and genetic factors to the poor performance of black children on IQ tests as compared to white children.
Method: trans-racial adoption participants who were African American children from low IQ backgrounds were adopted by middle-class white families.
Findings: no significant difference in IQ correlations. They were found to have an average IQ of 106 at the age of 7. Whereas children of a similar background brought up in low income biological families has an average IQ of 97. The IQs of the adopted African American children was tested years later. By the age of 17, their IQs has dropped to 97, same as the average children from similar background brought up in the biological families (Weinburg et al 1992)
-To some extent as they found no significant difference in IQ correlations. However, overall it does not support Bouchard as they said 70% down to genetics whereas Scarr and Weinberg suggests to more a mix of genetics and the environment.
Caspi et al (2003)
Aim: to investigate the relationship between the 5-HTT gene and depression.
Method: a longitudinal study involving 847 participants. Two types of 5-HTT genes-
1. Long-little of 57% population.
2. Short- 43% population.
The researchers compared participants with normal 5-HTT (long) genes and a mutation of the 5-HTT gene with shorter alleles specifically after stressful events.
Findings: after stressful events, the participants who carried a mutation of the 5-HTT gene (and has experience many stressful events) were more likely to become depressed than the participants that carries that normal 5-HTT gene.
The 5-HTT gene could suggest vulnerability to depression after stress.
Evaluation: since so many people carry the mutation of the 5-HTT gene, it’s hard to conclude that it is the gene that makes/made the difference. That the gene made a major contribution to depression. (people who carried the other variation also became depressed).
It could have been environmental factors (stressful events) that caused depression.
The study showed a correlation between the presence of 5-HTT short allele and depression, a cause-effect relationship can’t be established.
