PSYC 110 Lecture Notes - Lecture 11: Direct Current, Narcolepsy, Spatial Memory
27 Jun 2018
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Regions of the brain tend to grow when used and to atrophy when not used.
Experience can change the structure of the brain -> rats were housed in enriched environments (large
cages with many objects to hold) or deprived environments (small cages with nothing except food and a
water bottle). After weeks, the brains of the rats from both groups were checked. Brains of the rats in
the enriched environment had thicker cerebral cortexes, larger cortical neurons, more acetylcholine
(neurotransmitters), more synapses than did those in the deprived environment. These differences were
observed until adulthood. Better learning ability in the enriched environment.
Researchers believed this was due to brain growth from modification of existing neurons and addition of
new glial cells (non neural cells that provide nutritional and structural support). We believed new
neurons were not produced in mammalian brains after birth but new research shows it is possible in
certain areas of the brain.
Generation of new neurons -> most found in the hippocampus. Noticed in rats of the enriched
environment. Make learning and memory better.
As a developing infant, you have 200% of the neurons you'll have as an adult. If you use it, it will grow.
With kids - giving them more experiences - different sorts of hobbies so the brain cells have the
opportunity to wire up - different experiences to learn what the kids are drawn towards and how to
make it as enriching as possible
Kids who grow up in a school district compared to kids who grow up in poor areas - children in enriched
environments grow up to have more successful careers - long term effects of environment
Bucharest Early Intervention Project: 1960s, in Romania they had a dictator named Nikolae - Increase his
population, he will have more power - passed laws of taxes for families with less than 5 children,
mandatory gynecological appointments, not allowed women to use birth control - convinced the
population the state could raise the children better than parents could - led to a lot of child
abandonment & institutionalization - by 1989, 170000 children in institutions - they wanted to change it
but they need empirical evidence to prove the mess - they had a limited budget but they took the
money and made a randomized controlled trial of foster care as an intervention for the children placed
in the institutions - there was a lot of division between children and they did not socially interact with
each other, super sterile not enriching, the resources are bare minimum, it was very quiet or no crying
of babies (think through classical conditioning, crying a lot but still no response so they stopped crying),
nothing to play with
They knew behaviorally there were a lot of issues: acting out, no emotional attachments, autism-like
symptoms, inattention or hyperactivity, growth stunting
Question was is it due to this environment? Bucharest project tried to prove this by showing evidence -
worked with 208 children (longitudinal studies) - took 68 and assigned them to institutionalized care and
68 for high quality foster care and tried to compare all of these to 72 children living with families -
Independent variables: institutionalized, foster care, non-institutionalized
Dependent variables: IQ, brain volume, psychiatric evaluations
Measured at: 30, 42, 54 months and then at 8 years
Was this study ethical?
Highest IQ in kids with parents but IQ of institutionalized and foster kids went down between 18 and 54
months
Foster care is associated with higher volumes of cortical white matter -> Brains are more enriched
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Critical Periods for Certain functions:
ADHD symptoms are not significantly reduced in those placed in foster care at any age
Institutionalization results in disrupted cortical development and reduced thickness in many
cortical areas
These reductions in thickness explain elevated ADHD symptoms in institutionalized children
Foster care has a lasting impact on brain and cognitive development - changing all over the world to
help these kids get as much enriched environment
Gregg Recanzone -> trained monkeys to discriminate between subtly different rates of vibrations
applied to a particular patch of skin on one finger. Received banana pellets for responding to the
vibration. "Untrained" monkeys received the same vibration but they were not rewarded. Noticed that
the monkeys that were rewarded had a larger area of cortex because of the reward received.
In stringed-instrument players, large areas of somatosensory cortex responded to stimulation of the
fingers of the left hand (the same fingers they used to play music for years).
Occipital lobe guides visual input for sighted people but for blind people, it becomes devoted to various
other purposes to compensate for the blindness i.e task of identifying the location from which the
sounds are coming, analyzing tactile input
Birds caching their seeds -> mountain chickadee -> enlargement of hippocampus partly depends on
experience. Hippocampi expands when allowed to hide and retrieve seeds and it shrinks when
prevented from hiding and retrieving.
Hippocampus is involved in many forms of memory - especially, spatial memory.
Cab drivers in big cities -> develop spatial abilities -> in London have to test spatial skills to drive through
the shortest route. Posterior part of the hippocampus is the largest in London cab drivers than in people
who do not drive taxis. -> the longer a person had been driving taxi, the larger was the posterior
hippocampus
Skill learning causes larger portions of the brain to become involved in performing that particular skill.
Learning strengthens synaptic connections between already existing neurons.
Donald Hebb: Some synapses in the brain have the property of growing stronger whenever the
postsynaptic neuron fires immediately after the presynaptic neuron fires.
Neurons could acquire the capacity to respond to input that they previously didn't respond to -> could
be a basis for classical conditioning and learning.
Long term potentiation (LTP) -> produced by artificially stimulating a bundle of neurons entering a
particular region of an animal's brain.
Interference with the brain's normal capacity for such potentiation interferes with the animal's ability to
learn.
Mice -> drug that prevents LTP was injected into a portion of amygdala -> researchers tried through
classical conditioning to train the mice to fear a tone that was paired with an electric shock. The LTP
inhibited mice failed to learn such fear. They responded to the shock but did not show fear responses to
the tone.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Regions of the brain tend to grow when used and to atrophy when not used. Experience can change the structure of the brain -> rats were housed in enriched environments (large cages with many objects to hold) or deprived environments (small cages with nothing except food and a water bottle). After weeks, the brains of the rats from both groups were checked. Brains of the rats in the enriched environment had thicker cerebral cortexes, larger cortical neurons, more acetylcholine (neurotransmitters), more synapses than did those in the deprived environment. Researchers believed this was due to brain growth from modification of existing neurons and addition of new glial cells (non neural cells that provide nutritional and structural support). We believed new neurons were not produced in mammalian brains after birth but new research shows it is possible in certain areas of the brain. Generation of new neurons -> most found in the hippocampus.
