Biological study studies Flashcards
(18 cards)
Rogers and Kesner
Aim: Investigate the role of acetylcholine in memory formation.
Method: Administered scopolamine (an acetylcholine inhibitor) to rats before navigating a maze.
Results: Rats given scopolamine made more errors in the maze.
Conclusion: Acetylcholine is important for the consolidation of spatial memories.
Caspi et al
Aim: Investigate gene-environment interaction for the serotonin transporter gene (5-HTT) in relation to depression.
Method: Large sample of NZ participants divided into three groups based on 5-HTT alleles:
Group 1: Two short alleles
Group 2: One short, one long allele
Group 3: Two long alleles
Participants completed a “Stressful Life Events” questionnaire and were assessed for depression.
Results:
Individuals with one or more short alleles showed more depression symptoms and suicidal ideation in response to stressful events.
The effect was strongest with increased stressors; inheritance of the gene alone was not sufficient for depression.
Conclusion: Interaction between genetic predisposition and environmental stressors increases the likelihood of developing depression.
Draganski
Aim: To investigate how learning a new skill (juggling) affects brain structure.
Method: Jugglers learned a three-ball routine (after an initial MRI) and had a second MRI after mastering it, followed by a third MRI three months later (after stopping juggling).
Results: Jugglers showed increased grey matter in the mid-temporal area, linked to visual memory, after learning to juggle. This increase diminished after they stopped practicing. Non-jugglers showed no significant changes.
Conclusion: Brain changes were associated with the practice of juggling, indicating that skills can lead to structural brain modifications.
HM:Milner
Aim: To examine the effects of surgery that removed parts of HM’s medial temporal lobes.
Results: HM developed severe anterograde amnesia, losing the ability to form new long-term memories but retaining childhood memories and motor skills.
Conclusion: Milner’s extensive research demonstrated the critical role of the hippocampus in converting short-term memories into long-term ones, significantly enhancing the understanding of memory localisation in the brain.
Maguire
Aim: To investigate the brain structure of London taxi drivers.
Method: Conducted a single-blind study comparing brain scans of right-handed London taxi drivers to right-handed males who were not taxi drivers.
Results: Found that taxi drivers had significantly larger posterior hippocampi and smaller anterior hippocampi compared to control subjects.
Conclusion: The study supports the idea of neuroplasticity, suggesting that the posterior hippocampus is involved in recalling spatial information, as taxi drivers rely on this knowledge daily.
Newcomer et al
Aim: To examine the effects of elevated cortisol on verbal declarative memory.
Method: Healthy participants were placed into one of three conditions:
high cortisol, low cortisol, and placebo. Participants recalled prose paragraphs at baseline, one day after, and four days after treatment.
Results:
The high cortisol group showed impaired recall. No significant differences between low-dose and placebo groups.
Conclusion: High cortisol levels negatively affect recall, indicating a link between stress hormones and memory performance.
Rogers and Kesner
Aim: To investigate the role of the neurotransmitter acetylcholine in memory formation.
Method: Rats were trained to navigate a maze, then injected with either scopolamine (which blocks acetylcholine receptors) or a placebo.
Results: Rats given scopolamine took longer and made more mistakes in the maze compared to the control group.
Conclusion: Acetylcholine is crucial for the formation and retrieval of spatial memory.
Rosenzweig et al
Aim: To study the effects of environmental enrichment on brain plasticity in rats.
Method: Rats were raised in either enriched or impoverished environments.
Results: Rats in enriched environments had thicker cerebral cortices and greater brain weight compared to those in impoverished environments.
Conclusion: Stimulation from enriched environments positively affects brain development and neural growth.
Weissman et al
Aim: To explore the genetic basis of Major Depressive Disorder (MDD).
Method: Families across three generations did a longitudinal study comparing high-risk (depressed family history) and low-risk (non-depressed family history) groups.
They were interviewed by clinicians who had no knowledge of their family history.
Results: Grandchildren with two preceding generations of depression showed a higher risk of developing psychiatric disorders.
The risk increased significantly when both grandparents and parents had depression.
Conclusion: The study suggests a genetic influence on the intergenerational transmission of psychiatric disorders, including MDD, particularly when depression is present across multiple generations.
Zhou et al
Aim: To investigate if certain chemical compounds communicate gender information, acting as human sex pheromones.
Method: Many people, of many sexual preferences, were experimented on. They examined the effects of two specific compounds on the perception of gender in moving figures.
Results: One compound biased certain groups (heterosexual women and gay men) to perceive figures as more masculine. The other compound biased another group (heterosexual men) to perceive figures as more feminine.
Conclusion: The study suggests that specific chemical signals convey gender information, influencing how certain individuals perceive masculinity and femininity.
Buss
Aim: To investigate mate selection preferences across a wide range of cultures.
Method: Over 10,000 respondents from 37 different cultures. Questionnaires were used to gather data on mate preferences.
Results: Women prioritized financial prospects more than men in almost all cultures. Men universally preferred younger mates, while women preferred older mates.
Specific cultural differences were observed in the ranking of traits like love, education, health, and domestic skills.
Conclusion: Mate selection preferences show universal patterns, likely influenced by evolutionary factors, but also exhibit significant cultural variations.
Cases et al
Aim: To investigate the genetic origins of aggression using genetically modified mice.
Method: Genetically modified mice lacking a specific gene (MAOA).
Procedure: Observed the mice for behavioral signs and conducted “resident-intruder” tests to assess aggression. Autopsies were performed to examine neurochemical levels.
Results: Mice without the specific gene showed offensive aggression and threatening behaviors. These mice also had elevated levels of certain neurotransmitters in their brains.
Conclusion: The absence of the specific gene leads to a predisposition towards aggressive behavior in mice, suggesting a potential similar link in humans.
Kendler et al
Aim: To investigate the heritability of major depression, including gender differences and changes in influencing factors over time.
Method: A large number of twin pairs from a national registry. Telephone interviews were conducted to assess lifetime major depression using established diagnostic criteria. Data on environmental factors was also collected.
Results: Higher concordance rates for major depression were found in women compared to men. Identical twins showed significantly higher concordance rates than non-identical twins.
Conclusion: Major depression shows higher heritability in women, suggesting some gender-specific genetic risk factors. The study supports the use of twin studies for understanding major depression.
Meaney
Aim: To explore how glucocorticoids (stress hormones) affect memory in rats.
Method: Rats were divided into:
Treatment Group: Handled daily for three weeks to simulate maternal grooming.
Control Group: Removed from mothers but not handled.
Memory Test: At two years old, rats were placed in a pool to find a hidden platform, and their routes were tracked.
Findings:
Control rats showed significant memory deficits and hippocampal neuron loss.
Treated rats exhibited better memory and less cognitive decline.
Conclusion: Early grooming activates genes that improve stress response and memory, demonstrating an epigenetic link.
Sapolsky et al
Aim: To investigate the impact of social hierarchy on cardiovascular health in a troop of baboons.
Method: Longitudinal and naturalistic study in Western Kenya. Included observations, physiological tests, and experiments.
Results: Baboons at the bottom of the social hierarchy experienced chronic stress, leading to elevated levels of glucocorticoids (cortisol).
Long-term stress exposure correlated with negative health outcomes, (heart problems etc)
Conclusion: The study highlights the significant role of social stress in influencing health, particularly through hormonal responses associated with hierarchical positioning.
Troster and Beatty
Aim: To examine the role of acetylcholine in memory formation and retrieval.
Method: Adult men received either a placebo or varying doses of a substance that inhibits acetylcholine (scopolamine) across different sessions. Multiple memory tests were administered.
Results: The acetylcholine-inhibiting substance impaired the encoding of new memories. However, the ability to recall long-term memories remained unaffected.
Conclusion: Acetylcholine is essential for the encoding of new semantic and spatial memories, confirming its critical role in memory formation.
Wedekind
Aim: To investigate whether Major Histocompatibility Complex (MHC) influences mate choice.
Method: Male and female university students with diverse MHC types, were the participants. Men wore T-shirts for two nights under controlled conditions to collect their natural scent. Women then smelled and ranked the pleasantness, intensity, and sexiness of T-shirts from men with similar and dissimilar MHC, as well as an unworn shirt.
Results: Women generally rated the odor of men with dissimilar MHC as more pleasant. This preference was altered in women using oral contraceptives.
Conclusion: The study suggests that MHC influences mate choice, likely through scent, and this effect can be modulated by hormonal factors.
Antonova
Aim: To examine the effect of a specific neurotransmitter blocker (scopolamine) on brain activity during spatial memory tasks in humans.
Method: Healthy adult males were the participants. Participants received either the blocking substance or a placebo, then performed a spatial navigation task while their brain activity was measured using fMRI. Double blind study
Results: The blocking substance significantly reduced brain activation in the hippocampus during spatial navigation.
Conclusion: The findings indicate that the neurotransmitter acetylcholine is critical for encoding spatial memories in humans.
