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Lecture 8

PSY210H1 Lecture Notes - Lecture 8: Detection Theory, Tube Socket, Lectern

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March 14, 2011
Genetics, epigenesis, and plasticity con’t
Zero in on a specific chapter in the textbook, read it, then do
independent work to find relevant journal articles good idea to read
stuff by the people cited in the textbook
Use at least 10 journal articles, MUST be peer-reviewed, ideally within
the last 10-15 years
Books are okay only within the last 5-10 years, and if their authors
have written in peer-reviewed journals
Older your sources, more likely they’re irrelevant now
APA format only include the things you actually cited, not things you
just read
o In-line citations
Genetics, epigenesis, and plasticity
Becoming increasingly more difficult to separate nature and nurture,
which is why this debate is dissolving
What would lead us to think that environment is not independent
from genes but that genes are independent from environment?
What’s Lamarkian evolution?
o The idea that animals can pass on acquired characteristics
o Fairytale version of Lamark why giraffe’s have long necks –
they stretched lots to get to tall trees, did lots of giraffe yoga,
and their necks got a little longer, and they passed that on to
their kids, etc etc
o Before Darwin, this was a plausible solution
But now we know better people synthesized Darwinian evolution
with Mandelian genetics - there’s nothing we can do to pass on
acquired characteristics to your offspring if you lose a leg in an
accident, you’re not going to pass on the loss of a leg to your child
This seems to imply that genes can’t be affected by the environment
only across generations (mutations, genetic drift)
How to make a distinction between gene structure and gene activity -
yes, the genes themselves cannot be affected by the environment, but
how they are turned on and off can
This is a large part of epigenesis
Neuroplasticity = significant influence of environment on gene
Genes --> gene activity <--> enzyme protein -> muscles/neurons

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How is there feedback between gene activity and enzyme protein?
Enough protein will turn off gene two-way causation
Hugely affected by biological factors
Feeds back to other levels feedback loops within feedback loops
within feedback loops self-organizing system
Each level can be described as either nature or nurture not clear
which can be described as which as any given time
“the environment” isn’t a single thing – a room, a building, a country,
etc even your body can be considered an environment nature and
nurture are no longer independent or singular there isn’t a single
part of the diagram we can point to and say “THIS is the environment”
or “THIS is nature”
genes shape environment, environment shapes all gene activity and
this means we have a new account of what development means
o development used to be learning, maturation, additive
interaction between the two
o the above is neither learning, or maturation, or simply a
combination of the two development is EMERGENCE
Bjorklund’s theory, example of little girl learning to play violin
from earlier lecture
dynamical systems are simultaneously integrating into wholes and
differentiating into parts
complex systems produce emergent functions, new abilities this is
what it means to be a complex system more different kinds of
interaction with the environment while maintaining your integrity as
an organism/system
brain = epigenesis on speed, in a way tremendous plasticity
two types of plasticity synaptogenesis and neurogenesis
o synaptogenesis ability to grow new synaptic connections or
kill existing ones
o neurogenesis ability to grow new neurons or kill existing
this process is directly affected by environmental factors
certain behaviours can lead to cortical thickness if you are a violin
player, the part of your brain associated with fine fingers movements
will be bigger and stronger
long term meditators have increased introspective awareness - “you
can train your mind to change your brain”
your brain is a machine of machines that can make itself into a new
kind of machine way more advanced than a computer
computers are only capable of quantitative development not

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emergence through dynamical systems is one of the most powerful
explanations as to why development occurs in a stepwise pattern
dynamical system that occurs between nature and nature has much
more to do with development then genes or environment on their
emergent dynamical system shapes development in powerful ways
MAOA enzyme that is a catalytic reaction for several
neurotransmitters in the brain MAOA levels are correlated with
increased aggression and anti-social behaviour
o People who have done research on this:
o Caspi et al 2002
o Bjorklund
o Mark Lewis
Correlations between MAOA levels, child maltreatment
and antisocial behaviour as well study aimed to look
at all three factors
Maltreated boys predictive of antisocial behaviour,
especially for children that had low MAOA
Lower MAOA on its own was not correlated with highly
anti-social behaviour
Only low MAOA and maltreatment as a child greatly
predicted antisocial behaviour
Maltreatment as a child generally predicted anti-social
and aggressive behaviour
o Epigenetics species of interactionism
Brain is constantly redefining itself as a dynamical
Highly accelerated in the brain
Push itself to qualitative change
Bronfenbrenner and Ceci’s bioecological model
o Very good at accommodating the facts of epigenesis and
o Layered environment environment does not refer to a single
o Proximal process genes can only exert this influences when
certain experiences activate them interactions between the
child and its direct contact environment
o Proximal processes must occur regularly and for an extended
period of time
o Degree to which environment supports proximal processes
and the regularity and duration of these process has a large
impact on gene expression and activity, hence it is a
bioecological model
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