biological studies Flashcards
Neuroplasticity
The ability of the physical structures within the brain to change according to our experiences.
Neuroplasticity study
Rozenwing, bennet, and diamond
Aim: To determine the effect of a rich or impoverished environment on physical structures of the brain (cerebral cortex)
Procedure:
3 conditions
1: The impoverished environment. Three rats were put into independent cages, with no active or visual stimulation (toys or decorations) present.
2: The enriched environment. 10-12 rats were placed in a cage and surrounded by stimuli.
3: control. Three rats were placed in one cage together, with no additional stimuli.
-all groups had adequate access to food and water
-all were in their respective condition for 30-60 days
Findings
rats in the enriched condition experienced accentuated thickness and growth in the cerebral cortex, and displayed evidence of greater neural transmission of acetylcholine (good for memory and learning)
-study suggests that growth can occur in the brain as a result of an enriched environment.
(can be used for HL, rats were killed)
Neurotransmitters
Chemical substances that are used in the brain and body to send bio-chemical messages which dictate behavior.
Neurotransmitters study
Rogers and Kesner
Aim: to determine the role of acetylcholine in the formation of spatial memory.
-30 rats were acclimatized to a Hebb Williams maze, where they were required to find food placed in one of it’s corners.
-Once the rats had run the maze a few times, they were randomly assigned to one of 2 conditions.
Antagonist: half of the rats were given a scopolamine injection, which blocked the reception of acetylcholine in neural receptor sites.
Placebo: half of the rats were injected with a saline solution which produced no biological effect on the rats. This was done to reduce the confounding variable of adrenaline production.
-injections were made directly to the hippocampus.
-The rats then went through the maze again, the researchers were testing to see which group better retained their memories of the maze.
-encoding of memory was assessed by the average number of mistakes made in the first 5 trials of day 1 compared to the last 5 trials of day 1. Retrieval was assessed by comparing the average dumber of errors on the first 5 trials of day 2 compared to the last 5 of day 1.
-The Rats who received the scopolamine injection took longer to find the food and made more mistakes in the process in the last 5 trials of day 1.
-encoding was impacted. however, retrieval of memories that had already been created did not seem to be impacted.
-Acetylcholine appears to be vital in the encoding of memory, that is, transferring it to long term.
Genetics/genes
Genes are the building blocks of the features of all living things. They are made out of DNA, and dictate the features of a person based on the features of their parents.
Genetics study
Cases et al
TRANSGENIC: a being that has been artificially modified at a genetic level to include a foreign sequence
Aim: to determine the genetic origins of aggression
Procedure:
-Transgenic mice were used, they had the gene that regulates production of monoamine oxidase A (MAOA) (an enzyme that breaks down serotonin and norepinephrine) ‘knocked out’
-To test the impact of genetic variation, one mouse was introduced to the cage of another mouse.
-when a mouse was introduced to a control mouse, it would engage in an excited manor with the ‘intruder’ mouse
-when a mouse was introduced to a transgenic mouse, it would adopt a threatening hunched position and engage in aggressive behavior
(true regardless of gender of mice)
-autopsies of mice brains displayed that there were increases in serotonin, dopamine and norepinephrine. Dopamine levels were 6-9x more elevated in t mice than c mice.
-study displayed that when the MAOA gene is made deficient, mice tend to behave more aggressively
-researchers concluded that a depletion in the MAOA gene leads to a biological predisposition towards aggressive behavior that presents itself in social environments
-study was replicated in humans and showed similar results
Epigenetics
The study of how interaction with an environment can change the way in which genes function.
Epigenetics study
Caspi et al (can also be used for hormoes)
Aim: to determine the role that gene mutation and epigenetics may play in major depressive disorder
Procedure:
-this study is built off Diathesis-stress theories of depression, which suggest that an individuals reaction to certain stressful events depends on their genetic makeup, that if an individual had a specific genotype, then interaction with their environment may cause those genes to be expressed.
-This study was conducted to determine if there is evidence that interaction between genes and an environment can cause a mutation in the serotonin transporter gene (5-HTT) which is involved in the reuptake of serotonin by brain synapses
-a sample of 847 NZ 26 year olds that has been assessed for mental health every second year until they were 21.
-they were divided into 3 groups based on the expression of their 5-HTT genes
group 1: had 2 short alleles
group2: 1 short 1 long
group 3: 2 long
the mutation of the 5-HTT gene has the shorter alleles
-each participant was asked to fill out a questionaire that asked them about stressful life events, which asked them about the frequency of different life stresses regarding such things as finance, employment, relationships, health etc that occurred between the ages of 21 and 26,
-participants were all assessed for depression.
results
-those who had 1 or more short alleles displayed more symptoms of depression and suicidal ideation in response to stressful life events
-the effect was strongest for those that had experienced 3 or more stressful life events
-the gene itself does not cause depression, but it increases the likelihood, as ones reaction to stressful events will be altered.
this study is correlational, no manipulated IV.
the study has not been successfully replicated.
demand characteristics may have occurred in the survey.
holistic approach, evaluates biological and environmental factors.
Kinship studies
Studies that are conducted to test the effects of genes on the behavior of those in the same family. People who are exposed to different environments but have similar genes, they test whether our behaviors are more a result of our environment or our genes.
kinship study
Weissman et al
Aim: to study the potential genetic nature of Major Depressive Disorder
Procedure:
-a sample of 161 grandchildren, along with their parents and grandparents were all evaluated over a course of 20 years for MDD and other mental conditions such as anxiety and alcohol dependency.
-The original sample of depressed patients were selected from a outpatient clinic that specialized in the treatment of mood disorders. The non-depressed participants were selected from the same local community.
-this set of participants and their children were interviewed four times during the 20 years
-the original sample of children eventually grew up and had children of their own which allowed for the study of a third generation.
-Data regarding mental health was collected from clinicians, blind to diagnoses of depression or previous material from interviews.
-researcher triangulation: children were evaluated by 2 experienced clinicians, one a child psychiatrist and the other a psychologist
Results
-there were high rates of psychiatric disorders in grandchildren with two preceding generations with depression
-by 12 years old, 59.2% or grandchildren were showing signs of psychiatric disorders (most commonly anxiety)
-children had a higher risk of depression if it had been observed in their parents and grandparents than children who’s parents were not depressed
-the severity of a parents depression directly related to an increased rate of mood disorder in children
-if a parent was depressed but there was no history of depression in the grandparents, there was no significant effect of parental depression on the grandchildren
Evolutional theories of psychology
The idea that the reason we have developed our thinking in the way that we have is because of environmental factors which shaped our biological makeup throughout the process of evolution.
Evolution study
Ronay & von Hippel
Aim: to determine if men would make more risks in the presence of an attractive female than in the presence of a male (testosterone was also measured as a factor), as Intrasexual selection dictates that the most impressive male has better chances of pro-creation
-A sample of 96 young adult Australian male skateboarders with a mean age of 21.58 was selected
-all participants were asked to perform one easy trick and one difficult trick (with a success rate of ~50%) ten times each.
-after a break they were asked to make 10 more attempts of each trick
-43 did so in front of the same male researcher
-53 did so in front of an attractive female researcher who was blind to the hypothesis
-attractiveness was established by having 20 male raters view photos of women (ew).
-skateboard move outcomes were coded for one of 3 outcomes, success, crash or aborted attempt
-high levels of aborted attempts were seen as low-risk taking
-saliva was collected to measure testosterone levels and heartrate was measured by a heart-rate measuring watch. measurements were taken immediately prior to and throughout the test.
RESULTS
-participants took greater risks in front of the female researcher (less aborted attempts)
-testosterone levels were higher in those who skated in front of the female
-no sig difference in heart rate
-young men take greater risk in front of women and testosterone may be a factor in this
-increased risk-taking is a sign to potential mates that the male is strong ang capable of facing ‘danger’
-same time of day for all tests
Ethical guidelines in psychology
1: no undue stress or harm
2: no unjustified deception
3: debrief
Ethics studies (HL)
Harlow (1958)
(this one is DODGY)
Aim: to study the effect of isolation or integration on human attachment
procedure:
-immediately after birth, infant rhesus macaque monkeys were removed from their mother
-these monkeys were kept away from contact with other monkeys for a period of 3 months to one year
-they were then put in an environment with other monkeys to determine how the lack of parental care would effect their behavior and interaction
RESULTS
-monkeys displayed abnormal behavior like rocking and self-mutilation
-they were afraid of other monkeys and would attack them
-they were unable to socialize with other monkeys
-those that were separated the longest never recovered
-some argue that this study was valid as it gives us an understanding of the role that human attachment plays in mental health
pheromones
Substances which are secreted by one member of a species and received by another member of that same species
