Flashcards in 20 Gene-Environment Interactions Deck (23)
What is Pavlov's idea of equipotentiality?
Any stimulus can be associated with any other stimulus, no matter what they are
How did Garcia and Koelling (1966) demonstrate the biological preparedness to form associations between certain stimuli?
Rats in arena given saccharine water. Every time they drink they get AV stimulus (a click and flashing light.)
In condition 1, the rats were poisoned - drinking made them sick
In condition 2, the rats were shocked - drinking made them feel pain
In a subsequent trial, the rats who were poisoned would not drink saccharine water; the rats who were shocked would drink saccharine water but stop if exposed to AV stimulus.
So... Condition 1 rats formed association between taste and feeling sick
Condition 2 rats formed association between AV and feeling pain
Tastes preferentially associated with sickness
AV stimuli preferentially associated with pain
Do all species show similar biological preparedness?
No, pigeons, for instance, more readily associate colours with sickness, rather than taste with sickness
How did Susan Mineka prove existence of evolved module for fear learning in monkeys?
Lab-raised monkeys observed other monkeys show fear to flower –> no fear conditioned.
Lab-raised monkeys observed other monkeys show fear to snake –> YES fear conditioned, even if never encountered/bitten by snake.
How can instincts interfere with learning?
A natural SSDRI such as flight can interfere with approach learning, for instance. Also, raccoon dropping coins into moneybox example. Behaviour towards moneybox shaped with food, but couldn't get raccoon to let go because coin associated with food. Same for pigs and chickens - once object associated with food, object treated like food.
How did Cooper and Zubek (1958) demonstrate differential benefits of environmental enrichment for dull and bright strain rats?
If environment enriched - big improvement for dull strain rats, no difference for bright strain.
If environment impoverished, big decrease for bright strain rats, no difference for dull strain.
What is the link between Alzheimer's disease and the oestrogen gene?
Women who carry the ε4 version of the oestrogen gene are much more likely to develop Alzheimer's than rest of population
How does Alzheimer's treatment efficacy vary depending on genotype in women? And what does this show about how genes work?
Hormone-replacement therapy slows down symptoms - UNLESS you have ε4 gene. Type of genes you have determines how you respond to environmental stimuli. Also head injury isn't linked to Alzheimer's UNLESS you have ε4 gene.
What two things does a gene do?
1. Makes other genes (duplication)
2. Makes RNA (transcription)
What does RNA do?
1. Switches genes on or off
2. Can have enzymatic activity
3. Can make protein (translation)
What do proteins do?
1. Regulate genes
2. Have ezymatic activity
3. Have structural role
4. Are used in signalling
How can environment modulate genetic process?
1. Whether gene is read or not - transcription control
2. Whether or not RNA is translated into a protein - translational control
3. Whether protein is rendered inactive - post-translational control
4. Natural selection of genotype in the first place
According two which two behaviours is rat maternal behaviour quantified?
Arch-back nursing (exposes nipples)
Licking and grooming
High maternal care mothers do lots of this; low maternal care mothers do little
Describe the Francis et al. (1999) rat adoption study?
Pups from low- and high-care mothers adopted out to either a low- or high-care mother - thus 4 groups. Anxiety measured by cross-
What did Francis et al. (1999) rat adoption study demonstrate about maternal behaviour?
Rats raised by high-care mothers are less anxious; girl rats raised by high-care mothers are high-care mothers - adoption effect, no genetic determinant.
(i) maternal behaviour linked to stress reactivity and
(ii) maternal behaviour is transmitted from one generation to the next
How did maternal care affect genetic activity of animals?
Amount of genetic activity for glutocorticoid receptors in hippocampus - important for regulating stress response - is less in rats raised by low-care mothers
What does the rat adoption demonstrate about importance of maternal care environment?
Environment can determine expression of genotype for the rest of your life
What does maternal care change in the cells of the brain?
In cells of low maternal care rats, there is less methylation of proteins in nucleus that bind the DNA. When DNA has fewer methyl groups, it is less easily read. This accounts for fewer glutocorticoid receptors in hippocampus of low-maternal-care rats.
How can poor maternal care start a vicious cycle?
Girls given low maternal care have reduced expression of genes important for regulating stress. Grow up as stressed adults and are less likely to give adequate care to daughters. Cycle continues unless maternal environment is changed.
What do the starved post-WWII Dutch children prove about the interaction of genes and environment?
Starved Dutch more likely to be depressed, and much less methylation (hypomethylation) of DNA than in non-starved Dutch
What cause has been posited to explain why one MZ twin might have schizophrenia and the other not? (discordant SZ in MZ twins)
Changes in gene methylation account for almost all the rest of variance in correlation of expression of SZ between MZ twins. Some environmental factor cause methylation of genes of one twin but not the other -> environment regulates expression of genes
What's an epigenetic explanation for IQ?
Children raised in impoverished environment -> low IQ, so grow up and raise their kids in impoverished environment -> low IQ. Cultural inheritance, not genetic inheritance.