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Lecture 4

PSYCH 1XX3 Lecture 4: Neuroscience 2


Department
Psychology
Course Code
PSYCH 1XX3
Professor
Joe Kim
Lecture
4

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The medulla is a region in the hindbrain that can be further divided into several
sub regions
Rostral ventral medial medulla
Rostral (towards the top), ventral (in front of the neuraxis), and medial
(towards the midline of the brain)
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Can neuroscience explain siblings' drastically different behaviours?
Studying the Brain
Lesion Studies:
It takes special techniques to study the structure and function of the brain
Lesion studies, single cell stimulation and recording with popular
neuroimaging techniques
Brain injury links brain anatomy with behavioural deficits
Phineas Gage Case Study:
In 1848 Phineas Gage was a foreman of a railway construction crew
and he was known to be intelligent, full of life and likable
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An accident occurred and a rod went through his cheek bone and
Neuroscience 2
Tuesday, January 1, 2019
2:13 PM

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and he was known to be intelligent, full of life and likable
An accident occurred and a rod went through his cheek bone and
into the front part of his brain, and this resulted in him becoming
selfish, profane, erratic and unreliable
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It was a 3 foot iron pole
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Gage's case provided support for the view that the brain has
specialized structures for complex behaviours
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Lesion Studies must be specific to target the function of a brain region
Advantage: A direct measure of a brain structure's function. Use animals.
A researcher will destroy, remove or inactivate a defined brain region and
observe results on behaviour.
Disadvantage: Hard to selectively target particular regions and draw
conclusions. Brain is highly interconnected and often a variety of
behaviours are affected by a single lesion.
Solution: specific brain lesions can be studied in animal models
Another approach is targeted stimulation can also provide insight on brain
function
Electrically stimulating an area of the brain and observe the result on
behavior to build an anatomical map related to function
This technique was widely used by Canadian neurologist Dr. Wilder
Penfield to treat patients with severe epileptic seizures
Used microelectrodes
Single cell stimulation helped map behaviour to specific brain regions
Penfield perfected his "Montreal Procedure"
He needed to remove tissues while ensuring critical areas of the brain
would be left intact
The brain itself does not have pain receptors
This means patient can be under local anaesthetic and fully conscious,
working with Penfield to prove the exposed brain to locate and remove
the scarred tissue
Penfield used a small electric charge to stimulate the cortex
This stimulation leads to individual neuron fires and he could accurately
map perceptual processes and behaviours to specific brain regions
E.g. If Visual Cortex was stimulated, patient would report seeing flashes of
light
If Motor Cortex was stimulated they would report a muscle twitch
His work revealed specific function to previously unmapped regions of the
brain
Single cell recording reveals the function of individual neurons

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Electrodes can be used to record ongoing electrical activity in the brain
through single cell recording techniques
A small electrode is held just outside the cell body of an individual neuron
Neural activity is recorded while the animal performs a task or a stimulus
is presented
The pattern of firing reveals a particular neuron's functional role
For example, in a study for visual neuroscience, Hubel and Wiesel
presented cats with specific visual stimuli while recording single cells in
the visual cortex
In this way individual cell types were identified that responded to specific
categories of visual stimuli
Large- Scale brain structures are studied using neuroimaging techniques
To study large-scale structure and function of brain regions,
neuroscientists use structural and functional neuroimaging techniques
CT scans produce structural slices of the brain
The first structural neuroimaging technique that was developed was
computed tomography
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Relatively quick and inexpensive picture of brain
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Helpful to diagnose brain injuries
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Low resolution however
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MRIs provide higher resolution images of the brain
Magnetic Resonance imaging , powerful magnetic fields are
generated which align the hydrogen atoms found throughout the
brain
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