biological studies Flashcards
Feinstein et al 2012
Case study:
S.M has a rare genetic condition
Damage to both amygdalae (localized damaged)
bilateral lesions in her amygdalae
which
Previous studies show reduction in fear conditioning and recognizing fear
This case study tested ability to experience fear
Three tests
Pet Store
Haunted House
Scary Film Clips
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Took her to an exotic pet store
Observed and took notes of her reactions to the snakes and spiders
She says she doesn’t like them and “tries to avoid them”
Her reactions in the shop showed otherwise
She was intrigued, curious, touched the snakes, even said “this is so cool.”
She didn’t display any fear.
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Took her to a “haunted house”
An old sanitorium turned into a haunted house once per year.
5 other female volunteers joined.
Researchers followed and took notes of their behaviour.
The volunteers were scared and shrieking, whereas SM displayed no fear.
She even scared one of the “monsters” by mistake.
Radke et al 2015
Technique used to study the brain in Radke et al. (2015)
fMRI
Aim: to investigate relationships between perceiving a social threat, testosterone, and the amygdala
-54 healthy females
half given small dose of testosterone
half given placebo
laid in fMRI and shown pics of “happy” or “angry” faces
“Approach” or “avoid” faces as instructed to by researchers using joystick
Group with testosterone had more activation in amygdala when approaching angry faces and was higher approaching happy face
In situations involving social threat, people are more motivated to defend themselves, thus test increases activation of amygdala
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Group with testosterone had more amygdala activation viewing an angry face. More amygdala activation helps physically prepare to fight the threat.
testosterone levels prime and ready our brain to defend yourself against a threat. Motivation to defend yourself. higher amygdala activation leads to emotional readiness to react aggressively. However there is no impact on the PFC, so high testosterone does not directly imply aggression as PFC levels are normal and could still inhibit impulsive behavior.
Maguire et al (2001)
Aim: To investigate whether there is relationship between the number of years of driving a taxi and the anatomy of one’s brain
Method/Sample:
Quasi-experiment - Correlational study as the IV is not manipulated
2 groups of participants
16 right-handed male London taxi drivers ranging of ages (they had to complete “knowledge: test and have their license for at least 1.5 years to be eligible to take part of the study)
50 right-handed non-taxi drivers (control group)
MRI scan
Single blind control (researchers didn’t know whose brain they were looking at)
Procedure:
Participants brain were MRI scanned and taxi drivers anatomy was compared with non-taxi drivers
Taxi drivers brains were measured with VBM (measures density of gray matter in brain) and pixel counting (measures area of hippocampus)
Gray matter: where most neural connections lie in the brain
Results:
Positive correlation between the number of years participants were taxi drivers and size of the posterior hippocampus
Negative correlation between the number of years participants were taxi drivers and size of the anterior hippocampus
No differences were observed in other parts of the brain
Conclusion:
This demonstrates that the hippocampus may change in response to environmental demands and the hippocampal region is more involved during the encoding of new environmental layouts
It shows that the hippocampus, which is located in the limbic system, that is in the brain, carries out specific functions that is involved with the encoding of memory especially spatial information, such as the layout of London’s roads
Passamonti et al., 2012
-30 healthy participants
-Drank a tryptophan lacking drink, or placebo (different days)
-Low tryptophan = low serotonin
-But we can’t measure serotonin in the brain of living participants
Randomized order (some T→P, others P→T)
-Double-blind procedure.
-Viewed images of different types of faces (sad, angry, neutral)
-The participants were put in fMRIs and their brain activity was measured (to observe the activation of different areas
-The results showed that there was reduced activity in the frontal lobe during the low serotonin conditions when the participant was viewing the angry face. Moreover, communication between the amygdala and the frontal lobe was weaker in this condition.
Antonova (2011)
Aim: whether scopolamine, an acetylcholine inhibitor, affected hippocampal activity in the creation of spatial memories. Acetylcholine is a neurotransmitter that plays a role in motivation, attention, learning, and memory.
Method/Sample:
20 healthy male adults
Double-blind experiment
Procedure:
Participants were either injected with scopolamine or placebo.
Participants played a VR game where they had to find a pole, then restart the game and 30 seconds later, they would have to find the pole again but at a new spot in the arena.
They did this while under a brain scanner.
Participants returned 3-4 weeks later and redid the test with opposite treatment
Findings:
Those injected with scopolamine took longer on average to find the pole, and that there was reduction in activity in the hippocampus (in charge of encoding memory into long term).
Conclusion: This suggested that acetylcholine could be involved in the consolidation of spatial memories (as the accuracy was the same for both groups, only the time was different).
Draganski et al (2004)
Aim: Find out whether the human brain can change structure in response to environmental demands
Procedure: Random sampling design, self-selected sample
Randomly allocated a sample of volunteers into 2 groups
One : jugglers
Two : non-jugglers
Made sure that both groups had no experience of juggling before the start of the experiment
First MRI performed
Participants in the juggler group subsequently spent three months learning a classic juggling routine with three balls
Second MRI performed
Participants in the juggler group spent three months where they were instructed not to practice juggling
Third MRI performed
Results: Prior to the start of the experiment there was no difference in brain structure
Second scan the juggler had more gray matter in some areas of the cortex mostly the mid-temporal area
Third scan differences decreased but jugglers denser gray matter
Conclusion: If we practice something then our brain will increase and when we stop practicing then it will decrease again, but often not to its original state
Wedekind 1995
Aim: to determine whether one’s MHC would affect mate choice.
Sample: 49 female and 44 male students from the University of Bern, Switzerland.
Procedure: Men asked to wear T-shirts for two nights. Perfume-free detergent. Not use any deodorants, perfumes, no spicy foods, not engage any sexual activity.
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Two days later, the women were asked to rank the smell of 7 t-shirts during second week after beginning of menstruation.
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3/7 boxes contained men with MHC similar vs 3/7 MHC dissimilar and 1 unworn as control.
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woman ranked odours of intensity and pleasentness (0-10)
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male body odours more pleasent = differend
odour assessment
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reversed when taking oral contraceptives
Baker & Raine(2007)
&
Mason (1994)
Over 1000 MZ and DZ twins and triplets studied.
Antisocial behavior measured through self-report, teachers, and caregiver questionnaires.
Compared DZ & MZ twins antisocial ratings to create correlations
Overall results showed heritability was around 50%
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Aim
To investigate the extent to which anti social behavior can be attributed to genes (heritability of behavior)
Type of Experiment
Twin study
Participants
1,210 twins in California, USA
Procedure
Child, teachers, caregiver filled out questionnaires to test the child’s personality, behavior and social skills (anti-social behavior)
Results
Heritability of anti-social behavior always came to around 50%
Strengths
Data triangulation (from child, teachers and caregivers) - reduces the effect of individual bias
Limitations
1) Cannot establish a causational relationship
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Baker et al’s findings are supported by:
Meta-Analysis: 12 twin and 3 adoption studies carired out between 1975 and 1994 showed the same finding - 50% heritability for antisocial behaviour.
However, the effects of genetics was stronger in extreme antisocial behaviour, suggesting these types of extremes are more genetically based and less influenced by environmental factors.
Baker & Raine(2007)
Over 1000 MZ and DZ twins and triplets studied.
Antisocial behavior measured through self-report, teachers, and caregiver questionnaires.
Compared DZ & MZ twins antisocial ratings to create correlations
Overall results showed heritability was around 50%
—-
Aim
To investigate the extent to which anti social behavior can be attributed to genes (heritability of behavior)
Type of Experiment
Twin study
Participants
1,210 twins in California, USA
Procedure
Child, teachers, caregiver filled out questionnaires to test the child’s personality, behavior and social skills (anti-social behavior)
Results
Heritability of anti-social behavior always came to around 50%
Strengths
Data triangulation (from child, teachers and caregivers) - reduces the effect of individual bias
Limitations
1) Cannot establish a causational relationship
Meyer-Lindenberg, 2008
Meyer-Lindenberg et al. (2008) showed this in their study that compared the brain activity of two groups of healthy participants.
One group had high expressing MAOA gene (MAOA-H), whereas another group had the variant that has low expression of the MAOA gene, which is the type correlated with aggressive behaviour (MAOA-L).
When viewing angry and fearful faces in an fMRI, the MAOA-L group had significantly increased activity in their amygdala, and reduced activity in their ventromedial prefrontal cortex.
Buss 1989
AIM - wanted to test these evolutionary assumption to see if they can explain human mate selection
Method - questionnaire
Sample: 37 samples from 33 counties with 10047 participants. All countries had at least 100 participants except Iran. The sample was collected different ways: during wedding license application; systematic sampling; newspaper ads; high school students
Asked to complete 2 surveys
Survey 1
Biographical data and what age they preferred to marry, preferred age difference, who should be older, desired number of children
Asked to rate 18 characteristics on how important they are ona 4 point scale
Survey 2
Provided 13 characteristics that participants were asked to rank in terms of desirability in a mate
Results
36 out of 37 samples, women valued good financial prospects in a potential mate more than males
In all samples men preferred mates who are young, (avg 25) Age preference is close of peak female fertility
Females preferred older mates
34 out of 37 samples showed that males value physical attractiveness in potential mates more than females
23 out of 37 samples valued chastity.
Zhou (2014)
Method
–> 96 self-reported heterosexual and homosexual males and females.
–> The AND, EST and the control substance were placed in identical jars from which the participants inhaled.
–> ‘Point light displays’ were employed, with 15 light dots positioned at major joints of walkers (taken from male and female walkers on treadmills). There were point lights from 50 males and 50 females.
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RESULT
–> smelling AND biased heterosexual females and homosexual male participants to perceive the walker as male and smelling EST biased heterosexual males and homosexual female participants perceive them as females.
–> The results from bisexual and homosexual females fell in between those of heterosexual males and females.
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Conclusion
–> Hence, there is direct evidence that the two hormones communicate opposite gender information that has a differential effect on the two sex groups, based on their sexual orientation.
–> This also shows that human visual gender perception is the result of subconscious chemosensory biological cues
