CAS PS 241 Lecture Notes - Lecture 6: Synaptic Pruning, Synaptogenesis, Imitative Learning
14 Dec 2017
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February 14th
Developmental Psychology — Lecture 6
Each neuron forms synapses with thousands of other neurons, resulting in the formation of
trillions of connections — this is Synaptogenesis
Synaptic pruning occurs at different times in different areas of the brain and it is not fully
completed until adolescence. Some abilities come on line when appropriate levels of pruning
have occurred.
The process of pruning is going to occur between birth and adolescence. For each skill
(language, vision…) there is a different time. Pruning in general is not over until puberty, it is in
fact a long period of time.
Remember Baby video Alexandra with fragile memory.
Plasticity
The capacity of the brain to be affected by experience.
Synapses that are frequently activated are preserved.
Prior to birth, neurons have been wiring up in preparation for experiences, which the brain is
expecting.
Experience-expectant plasticity
The experience-expectant plasticity is the process through which the normal wiring of the brain
occurs in part as a result of the kids general experiences that every human who inhabits any
reasonably normal environment will have.
Example: you need to have visual experiences in the first few years of your life in order to
develop normal vision.
The plasticity that expects experience is accompanied by vulnerability: if the expected
experience is not available, development will be impaired.
A key element in experience-expectant plasticity is timing. There are a few sensitive periods
when the human brain is particularly sensitive to particular kinds of external stimuli. Different
capacities have critical, particular times.
Experiment Blakemoor and Cooper (1970)
From point of eye opening after birth, raised kittens in drums with either vertical or horizontal
lines for 5 months. Kittens were raised there.
When kittens were taken out, kittens raised with vertical lines couldn't see horizontal lines
(example: would trip over ropes horizontally stretched in front of them) and vice versa.
Parallel case with human babies.
What happens when human species-typical experiences do not occur?
Children in Romanian Orphanages during a communist regime (1989): social ill resulting from
“baby policy” which banned contraception and abortion (also, families that had more babies
were paid; pregnancies were being monitored illegally). Children in orphanages were denied
normal social-emotional contact and freedom of movement. Children in these orphanages had
no interaction with anybody.
Some children presented autism-like social impairments (no eye contact, not seeming to
understand someone’s voice…).
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Each neuron forms synapses with thousands of other neurons, resulting in the formation of trillions of connections this is synaptogenesis. Synaptic pruning occurs at different times in different areas of the brain and it is not fully completed until adolescence. Some abilities come on line when appropriate levels of pruning have occurred. The process of pruning is going to occur between birth and adolescence. For each skill (language, vision ) there is a different time. Pruning in general is not over until puberty, it is in fact a long period of time. The capacity of the brain to be affected by experience. Prior to birth, neurons have been wiring up in preparation for experiences, which the brain is expecting. The experience-expectant plasticity is the process through which the normal wiring of the brain occurs in part as a result of the kids general experiences that every human who inhabits any reasonably normal environment will have.
