Biology LOA Flashcards
Rosenzweig & Bennet (1972)
Aim
To investigate whether environmental factors such as rich or an impoverished environment affects the development of neurons in the cerebral cortex
Rosenzweig & Bennet (1972)
Procedure
Rats were played in either an enriched environment (EC) or an impoverished condition (IC).
● EC: 10-12 rats in a cage provided with different
● stimulus objects to explore and play with, and they also received maze training
● IC: each rat in an individual cage (isolation and no stimulation)
The rats typically spent 30-60 days in their respective environments before they were killed so the researchers would study changes in the brain anatomy
Rosenzweig & Bennet (1972)
Findings/Conclusions
The anatomy of the brain was different for rats in the EC and the IC
● The brains of EC rats had increased thickness and higher weight of the cortex, and had developed more acetylcholine receptors in the cerebral cortex
● The neurons in the EC rats had more dendrites i.e. more dendritic branching
Rosenzweig & Bennet (1972)
Evaluation
Strengths:
Experiment was a rigorously controlled laboratory experiment so it was possible to establish a cause-and-effect relationship
Limitations:
Experiment used animal models thus it may be difficult to generalize to humans unless research with humans provide the same results
Holland (1984)
Aim
To investigate whether there’s a genetic bases for anorexia by studying identical (MZ) and non-identical (DZ) twins, where at least one twin in each pair suffered from anorexia
Holland (1984)
Procedure
30 female twin pairs (16 MZ & 14 DZ), 4 male twin pairs, 1 set of male triplets
● Twin and triplets were selected because one of the twins (& the triplet) had been diagnosed as suffering from anorexia
● Data was collected on the other twin and triples to check for concordance
● MZ - monozygotic (identical) twins which are genetically identical because they were formed from one fertilized egg that split into two
● DZ - dizygotic twins (non-identical) which have 50% of their genes in common and formed by two separate fertilized eggs
● Concordance rate - correlation found where the higher genetic relationship, the more similar individuals will be if the particular characteristic being investigated is inherited
Holland (1984)
Findings/Conclusions
High concordance rates is 55% for MZ female twins, compared to 7% for DZ
· 5 of the non-anorexic female co-twins had psychiatric illnesses/eating disorders
· None of the male co-twins (or triples) had anorexia
· The anorexic male twins tended to have been disadvantaged at birth and to be the less dominant of the pairs
· No conclusions can be drawn from the data from male twins due to small numbers
· Results support the view that there is some genetic basis for anorexia among females, since identical twins (who share same genes) had 55% concordance, while DZ twins (who share half of same genes) showed only 7% concordance
Holland (1984)
Evaluation
Strengths:
The fact that the concordance was not 100% provides hope to sufferers that their condition isn’t an inescapable result of their biological makeup.
Limitations:
- The sample was very small, and the results may not generalize.
- It may be that factors other than genes are influencing these results; for example identical twins are likely to be treated differently from non-identical twins, and this may contribute to behavioral abnormalities.
Kendler et al. (1991)
Aim
To establish the prevalence (number of causes) of bulimia and to see whether there were genetic risk factors
Kendler et al. (1991)
Procedure
● 2163 female twins were given personal, structures, psychiatric interviews
● The twins were assessed for psychiatric disorders
● The risk factors for bulimia nervosa were recorded
Kendler et al. (1991)
Findings/Conclusions
● Prevalence of bulimia was 2.8% of those interviewed
● There are genetic risk factors involved in bulimia nervosa
● Risk factors for bulimia included; poor parental care, dieting and fluctuating weight, slim ideal body image, low self-esteem, feeling a lack of control over one’s life
● MZ twins - concordance was 23%, DZ twins - concordance was 8.7%
Kendler et al. (1991)
Evaluation
Strengths:
Collects a lot of data – good for large sample sizes as it is easier to generalize to a wider population,
Limitations:
No ethical issues as no one was harmed.
Fessler et al (2006)
Aim
To investigate whether the morning sickness experienced by pregnant women has an evolutionary basis (hypothesized that nausea response helps to compensate for suppressed immune system)
Fessler et al (2006)
Procedure
496 healthy pregnant women aged between 18 and 50 yrs old
● Women were asked to consider stomach churning scenarios: 1) walking barefoot and stepping on an earthworm 2) someone accidentally sticking a fishhook through their finger 3) maggots on a piece of meat in an outdoor trashcan
● Before making the women rank how disgusting they found the scenarios (survey), Fessler posted a series of questions to determine whether they were experiencing morning sickness (for those in 1st trimester, found food scenarios most disgusting)
Fessler et al (2006)
Findings/Conclusions
● Women in the 1st trimester of pregnancy scored higher on scores across the board on disgust sensitivity than their counterparts in the second and third trimester
● Many diseases that are most dangerous are food borne, but our ancestors could not afford to be picky about what they ate all the time
● Natural selection helped compensate for the increased susceptibility to disease during this risky period in pregnancy, by increasing the urge to be picky about food
Fessler et al (2006)
Evaluation
Strengths:
- Generalizability (large sample, wide age range)
Although it is restricted to women it could lead to insight on gender differences
- Quasi experiment : choice of pregnant women
- Well controlled: 32 images shown to each participant
Healthy women eradicating confounding factor of illness affecting responses
- Data was ranked by self-report - quantitative thus could use statistical analysis
Limitations:
- Findings can not be solely based on evolution, as the environment could be an interfering variable
- There is cultural and emotional influences on women’s disgust
- Quasi-experiment meaning that the IV could not be manipulated
- Data was ranked by self-report which is often unreliable
Individual differences in terms of food ‘likes’ and ‘dislikes’ and even paste food poisoning experiences will affect ‘rankings’
Curtis et al (2004)
Aim
To carry out research on the internet to test whether there were patterns in people’s disgust responses
Curtis et al (2004)
Procedure
Used an online survey in which participants were shown 20 images
● Among 20 images were 7 pairs which was infectious or potentially harmful to the immune system, the others were visually similar but not infectious (e.g. one pair was a plate of bodily fluids and a plate of blue viscous liquid)
● There were 77,000 participants from 165 countries
Curtis et al (2004)
Findings/Conclusions
● Disgust reaction was most strongly elicited for those images which threaten one’s immune system
● Disgust reaction decreases with age (also higher in young people than in older people)
● Women had higher disgust reactions than men
● The disgust reaction was strongest for images which threatened the immune system.
● Disgust also decreased with age and women had higher disgust reactions than men.
Curtis et al (2004)
Evaluation
Strengths: Applicable as it is ecologically valid Can be generalized Cost effective Time effective Some quantitative data
Limitations: No cause and effect No control over variables Low range of levels The study was conducted online The validity of the results is somewhat unreliable
Sekiguchi (2012)
Aim
To better understand post-traumatic stress disorder (PTSD)
Sekiguchi (2012)
Procedure
Researchers compared MRI brain scans they had taken of 42 healthy adolescents in other studies in the two years before the killer wave, with new images taken three to four months thereafter.
● Emotional stress caused by last year’s tsunami resulted in a part of some survivors’ brains to shrink, according to scientists in Japan who grasped a unique chance to study the neurological effects of trauma.
Sekiguchi (2012)
Findings/Conclusions
Among those with PTSD symptoms, they found a shrinking in the orbitofrontal cortex, a part of the brain involved in decision-making and the regulation of emotion, said a study published Tuesday in the Nature journal Molecular Psychiatry.
Conclusion: “The changed volumes in the orbitofrontal cortex are correlated to the severity of PTSD symptoms,” author Atsushi Sekiguchi told AFP.
“The changed volumes in the orbitofrontal cortex are correlated to the severity of PTSD symptoms,” author Atsushi Sekiguchi told AFP.
Sekiguchi (2012)
Evaluation
N/A
Draganski et al (2004)
Aim
To see if the structure of an adult human brain alters in response to environmental demands
Draganski et al (2004)
Procedure
● MRI was used for the PPs to visualize learning-induced plasticity in the brains of volunteers who have learned to juggle
● PPs: 21 female, 3 male, mean age: ABOUT 22 years
● This group was divided into two groups, designated as jugglers and non-jugglers (both groups were inexperienced in juggling at the time of their first brain scan)
● Subjects in the juggler group were given 3 months to learn classic three-ball cascade juggling routines
● A second MRI scan was performed when the PPs had become skilled performs (if they could sustain juggling for at least 60 seconds)
● A third scan was carried out 3 months later; none of the jugglers practiced or attempted to extend their skills
● Researchers used a voxel-based morphometry to investigate region-specific changes in grey and white matter by averaging results across the volunteers
Draganski et al (2004)
Findings/Conclusions
● Group comparison at the beginning showed no significant regional differences in grey matter between jugglers and non-jugglers
● In the longitudinal analysis, the juggler group demonstrated a significant transient bilateral expansion in grey matter in the mid-temporal area and in the left posterior intraparietal sulcus between the first and the second scans
● Individuals show a transient and selective structural change in brain areas that are associated with the processing and storage of complex visual motion
Juggling and the perception and spatial anticipation of moving objects, is a stronger stimulus for structural plasticity in the visual areas, than in the motor areas.
Draganski et al (2004)
Evaluation
N/A
Brefczynski-Lewis et al (2007)
Aim
To examine the differences in brain activity that might have resulted from being engaged in meditation over a long period of time
Brefczynski-Lewis et al (2007)
Procedure
12 meditators were recruited, 7 of which were asian. The meditators have experienced between 10,000- 54,000 hours of meditation practice in a Tibetan Buddhist method.
Asian meditators were compared to caucasian meditators with an interest in learning to meditate.
A 3rd group of PPs were promised financial incentive if their attention regions were most active.
● PPs were told to focus on one dot in front of a computer screen while at rest with no concentration
● fMRI scans were used to monitor their brains
● while experiment was ongoing, researchers played various noises in an attempt to distract participants from their meditation and force them to work harder to sustain attention.
● noises included a woman screaming, a baby cooing and a restaurant background noise.
Brefczynski-Lewis et al (2007)
Findings/Conclusions
● Attention-related networks in the brain and the visual cortex was more active during meditation than during rest periods
● Novice meditators would find it more difficult than experts to sustain their concentration, so this effort would be observed on the fMRI
● Experienced meditators showed less activation in areas of the brain associated with daydreams, emotional processing, and other thoughts not relating to the task
● Experienced meditators showed a response to the disturbing stimuli, not in terms of a change in attention away from the target of their concentration meditation, but in terms of adjustment of concentration (an active resistance being disrupted)
Differences are due to neuroplasticity, some kind of changes in the brain that have occurred over time as a result of sustained meditation
Brefczynski-Lewis et al (2007)
Evaluation
Limitations:
For the experienced meditators, they didn’t see the before and after image of their brains, therefore the researchers were not able to see the change in activity of their brains
Bremner et al (2004)
Aim
To measure the volume of the hippocampus based on the theory that prolonged stress may reduce the volume of the hippocampus due to increased cortisol levels
Bremner et al (2004)
Procedure
MRI scans took place to see the brains of the participants and the participants had to complete memory tests (e.g. remembering stories or a list of words). The participants were veterans and female adults who had experienced early childhood sexual abuse. Some also developed PTSD, but not all of them.
Bremner et al (2004)
Findings/Conclusions
Researchers found that there were deficits in the short-term memory and that the hippocampus was smaller in PTSD patients than in a control group. The veterans with most memory problems also had the smallest hippocampus.
The findings in this study showed a clear correlation between the number of years of abuse as measured by a trauma test, memory problems, and hippocampal volume. Also, people suffering from PTSD often suffer from other psychological disorder (e.g. depression) which could perhaps also play a role in the observed changes in the brain.
Bremner et al (2004)
Evaluation
Strengths:
The findings or a large reduction of hippocampal volume in combat-related PTSD have been replicated many times
Limitations:
The sample was so small that it was difficult for the researchers to conclude anything definite about the relationship between trauma and hippocampal volume.
Maguire et al (2000)
Aim
To see if fully licensed taxi drivers in London would have a different hippocampi structure in their brains compared to ‘normal’ people
Maguire et al (2000)
Procedure
Right handed male licensed London taxi drivers (32-62 years participated
· The average time spent training to be a taxi driver before passing licensing tests fully was 2 years
· MRI scans were used to scan the structure of their hippocampi, which were compared to existing MRI scans of healthy males who did not drive taxis
Maguire et al (2000)
Findings/Concolusions
Taxi drivers left and right hippocampi had a significantly larger gray matter volume compared to non-taxi drivers, which was focal.
There is probably a redistribution of grey matter in the hippocampi of taxi drivers due to the regular use of the spatial memory skills.
Connection:
The use of MRI in this study allowed for the researchers to—
· See that one important role of the hippocampus is to facilitate spatial memory in the form of navigation
· Observe the structure in the brain and find a correlation between the hippocampi (biological factor) and memory skills (cognitive process)
Maguire et al (2000)
Evaluation
Strengths: • No researcher bias • No ethical implications Limitations: • Only observed males • Only observed 16 matched pairs
Heston (1966)
Aim
Adoption Study on Schizophrenia
Study was to see whether schizophrenia (Sz) has a genetic
Heston (1966)
Procedure
● 50 adoptees whose biological mothers had been diagnosed Schizophrenia vs to control of 47 adoptees whose mothers had not been diagnosed w/ Schizophrenia
● Each participant had been separated from their mom during first few days of life
Researchers then:
● Compared psychosocial adjustment using school, police, and hospital records
● Proceeded with personal interviews and Minnesota Multiphasic Personality Inventory (a personality test in mental health)
● Had psychiatrists independently rate the participants
Heston (1966)
Findings/Conclusions
● Percent of incidents of schizophrenia in general population (which is 1%) was similar to those adopted with no family history of schizophrenia
● This study presented the idea that schizophrenia may be inherited, and therefore, a genetic component
● However, 10% (5 of the children) of the adopted children with a family history of schizophrenia were late diagnosed with schizophrenia
Heston (1966)
Evaluation
Strengths:
Rich qualitative data
Naturally occurring independent variable
Limitations: Unequal sample size: 47 compared to 50 Knowing that their biological mother having Sz No cause and effect Low control over variables Can’t be generalized
Martinez & Kessner (1991)
Aim
To determine the role of the neurotransmitter, acetylcholine (ACh) on learning memory.
Martinez & Kessner (1991)
Procedure
Laboratory experiment using rats. They were trained to run in a maze.
IV: level of ACh, DV: speed of maze completion and number of errors made by rats in
maze. They were divided into three groups:
● Group 1: received an injection with scopolamine which blocks ACh receptor sites - leading to LESS ACh in their brains
● Group 2: received an injection with physostigmine which blocks the production of an enzyme which cleans up ACh from the synapse - leading to MORE ACh in their brains
● Group 3: control group who were not injected with anything
Martinez & Kessner (1991)
Findings/Conclusions
● Group 1 had problems find their way through the maze and made more mistakes
● Group 2 ran quickly through the maze and made less mistakes, and was quicker than group 3 (the control group).
Conclusion: ACh plays an important role in creating a memory of a maze.
● shows that animal research can inform our understanding of human behavior
● animals and humans are not exactly the same, but there is a similar physiology
Martinez & Kessner (1991)
Evaluation
Strengths:
- The experimental method of this experiment makes it clear to see the cause-effect chain between the neurotransmitter acetylcholine and memory formation.
- Conclusions drawn from this experiment are therefore accurate.
- Multiple trials could have been easily performed
- Easily replicable
- Possiblity that humans can be treated with acetylcholine or physostigmine for memory-loss
- No differences in the role of acetylcholine between cultures (as rats were used, not people); results may be relevant for every human
- No people were harmed in this experiment
- No deception was used in this experiment
Limitations:
- Rats were harmed
- Ethical concerns to the extent that the rats suffered
- The results cannot be completely applied to humans
Baumgartner et al (2008)
Aim
To investigate the role of oxytocin after breaches of trust in a trust game
Baumgartner et al (2008)
Procedure
PPs replayed artist game used by economists and neuroscientists to study social interaction
● The “investor” (player 1) receives a sum of money and must decide whether or keep it or share it with a “trustee” (player 2).
● If the sum is shared, the sum is tripled.
● Player 2 must then decide if this sum should be shared (trust) or kept (violation of trust)
● fMRI scans were carried out in 49 PPs and they either received oxytocin or placebo via a nasal spray
· PPs played against different trustees in the trust game and against a computer in a risk game – in 50% of the games their trust was broken
Baumgartner et al (2008)
Findings/Conclusions
● PPs in the placebo group were likely to show less trust after feedback on betrayal, as they invested less
● PPs in the oxytocin group continued to invest at similar rates after receiving feedback on a breach of trust
● fMRI scans showed decreases in responses in the amygdala (the amygdala is involved in emotional processing and has many oxytocin receptors)
Conclusion:
If oxytocin is given to individuals, it seems that brain circuits in the amygdala involved in fear regulation are affected, and there is an increase in trust and generosity. It can also explain why peep are able to restore trust and forgive in long-term relationships.
Baumgartner et al (2008)
Evaluation
Strengths:
Oxytocin could explain why people are able to restore trust and forgive in long-term relationships.
Limitations:
· Scanner research is merely mapping brain activity but nothing definite can be said about what it really means at this point in science
· Low ecological validity - giving oxytocin may not reflect natural physiological processes, since the function of oxytocin is very complex
· It is too simplistic to say that it is “the trust hormone”
