PSYC23H3 Lecture Notes - Lecture 2: John Bowlby, Bulimia Nervosa, Mental Disorder
ACES Video
● Life experiences in childhood lost in time and
further protected by taboos play out half a
century later
● Obese lady gained weight after losing it bc of
harassment -- she had been sexually abused
as a child ]
ACEs vs. Genes
● What about cause and effect
○ Is it the adversity that is causing the
negative health outcomes or could
it be the genes that cause one to be
more vulnerable to adversity?
■ ACEs produce negative
outcomes
■ Bad genes cause negative
outcomes
● Can science give us an answer?
○ How do the animal models allow us
to test whether it’s the ACEs vs. the
genes?
■ Rats
■ Monkeys
○ What kind of human studies would
be necessary to make this same
determination?
○ What kind of ethical issues would
be involved?
Romanian orphans
● Kids rescued before the age of 2 had activity
similar to those with normal brains
Charles Nelson
● Number of mental illnesses as an adult
increases as early adversity increases
Question
● Why would low reactivity in heart rate and
cortisol to a social stressor be viewed as
maladaptive?
● Are differences in catchup rates caused by
the intervention or could there still be a
genetic component?
Nature vs. Nurture Interactions
Developmental Systems Theory (DST)
● Reciprocal relations between organism and
environment and genes and experience
● Subsystems interact
● Time is dynamic
○ The organism responds to the
environment; the organism changes
the next time is responds to the
environment
DST: Plasticity
● Epigenesis: an emergent process by which
an organism’s structure and function change
from relatively undifferentiated states to
increasingly specialized, differentiated forms
throughout ontogeny
○ Is it predetermined?
■ Genes → structural
maturation → activity and
experience
○ Or probabilistic?
■ Genes <-> structural
maturation <-> activity and
experience <->
Identical twins: the “natural” equivalent of clones
● Identical twins are nature’s controlled
experiment
○ They are born with the same genes
but different environments
○ This allows scientists to track the
influence of genetics
● Twins show us that physical attributes such
as height or certain diseases are in large
part determined genetically
○ But twins also exhibit a great deal
of difference, showing us that
environment plays a decisive role in
who we become
Assumption 1: Predetermined Epigenesis
● Everything we become is known in advance
○ All the information is in our genes
○ Developmental outcomes reflect the
expression of pre-existing forms
Counter evidence for assumption 1: predetermined
epigenesis
● Embryonic activity
○ Fibular crest connects tibia to fibula
(A)
○ When chick embryo is prevented
from moving within the egg, the
fibular crest bone (B) fails to
develop (C)
Assumption 2: Heredity as Gene
● Genes are the exclusive vehicles by which
these instructions are faithfully transmitted
from one generation to the next
Counter evidence for assumption 2: heredity as gene
● Intrauterine effects in gerbils
○ Females born in a litter of mostly
males will be exposed to more
testosterone
■ Greater delay in
maturation
■ Greater aggression
■ Great M:F ratio in future
litters
Assumption 3: Genes Encapsulated
● There is no meaningful feedback from the
environment or the experience of the
organism to the genes
● Contrary evidence from epigenetic studies:
○ Dutch hunger study
○ Maternal licking (rats)
Epigenetics
● Neurochemical changes that silence the
promoter regions (the “on” and “off” switches
of the DNA expression)
○ Methylation is one of several
mechanisms by which a promoter
region if the DNA can be regulated
by experienced-dependent
processes
● Multiple types of genes that we consider
○ Stress
○ Growth/metabolic
○ Sexual/reproduction
● Multiple types of experiences
○ Maternal behaviour/deprivation
○ Enrichment
○ Nutrition
○ Drugs
Dutch hunger winter study, Dutch “hunger winter” in
genetic material
● Fetal programming (the genes are listening!):
○ Prepares for an environment of
scarcity or plenty
○ Greater rates of obesity in adults
exposed as fetuses to severe
famine
○ Growth hormones like Factor 2
(IGF2) are overproduced in scarcity
○ Show epigenetic marks
(methylation)
Mechanisms (Meaney’s Team)
● Maternal behaviour in rats
○ Stable across multiple generations
○ Adult offspring who received low
licking/grooming compared to high
L/G
■ Heightened stress
reactivity
■ Less exploration in an
open field maze
■ Slower to eat food in a
novel environment
■ Increased HPA activation
to restrained stress
■ Decreased sensitivity to
the inhibitory effects of GC
on HPA activation
Study of holocaust survivors finds trauma passed on
to children’s genes
Panopticon
Intergenerational transmission of trauma
● 32 Jewish men and women
○ Survived Nazi concentation camp
○ Witnessed or experienced torture
○ Hid during second world war
● After the war is over, they went on to have
children
● Stress-related regions of the genes of these
children were chemically (epigenetically)
altered -- in the same way that trauma
typically is known to alter these genes
Experience transmitted across several generations
● Genetic inheritance vs. epigenetic
inheritance
How can an experience affect you -- if you can’t
remember it?
Can memories be passed down from our distant
relatives?
● Instincts and inherited behaviours represent
a kind of learning and memory that help us
survive:
○ Fight or flight
○ Parenting
○ Tend or befriend
○ Sexual or reproduction
○ Empathy or prosociality
Do informative experiences have to be experienced
by you to affect you?
● Mice taught to fear a certain smell pass this
information on to their children through their
sperm
Document Summary
Life experiences in childhood lost in time and further protected by taboos play out half a century later. Obese lady gained weight after losing it bc of harassment -- she had been sexually abused as a child ] Kids rescued before the age of 2 had activity similar to those with normal brains. Number of mental illnesses as an adult increases as early adversity increases. Reciprocal relations between organism and environment and genes and experience. The organism responds to the environment; the organism changes the next time is responds to the environment. Epigenesis: an emergent process by which an organism"s structure and function change from relatively undifferentiated states to increasingly specialized, differentiated forms throughout ontogeny. Genes structural maturation activity and experience. Genes structural maturation activity and experience They are born with the same genes but different environments. This allows scientists to track the influence of genetics.
