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PSYC 221 Lecture Notes - Transcranial Magnetic Stimulation, Positron Emission Tomography, Magnetic Resonance Imaging

Course Code
PSYC 221
Thomas Spalek

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Neurocognition 1
Terminal button attaches to dendrites of neighbouring neurons
Types of Neurons
1. Sensory neuron aka afferent neuron – from the external environment to the CNS
2. Motor aka efferent neuron – project away from CNS to muscles
3. Interneuron – form bridges between sensory and motor neurons (important
component of the reflex arc)
4. Pyramidal neuron – in the cortex – PRIMARY NEURONS ASSOCIATED WITH COGNITION
Nerve Communication
1. Polar – it has a positive and a negative end (e.g., a battery) (average = -70 mV)
2. Depolarize
3. Hyperpolarize (re-polarize)
4. Refractory period - keeps AP from only going one direction down the axon
Excitatory neurotransmitters like acetylcholine
Inhibitory neurotransmitters like GABA
If a target neuron is sufficiently excited will produce an AP transmit it’s NT to
the next neuron
AP is an all-or-none response that is always the same magnitude UNLIKE POST-
Anatomy of the Brain
Central fissure goes from the top middle of the brain and extends all the way down
the side to the ear
Corpus callosum = broad band of nerve fibres connecting the two hemispheres of the
White matter = myelinated portion of neurons in the brain; more dense
Gray matter = cell bodies in the brain

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Neurocognition 2
Structural Techniques
Lesions/brain damage
Virtual lesions – Transcranial magnetic stimulation (TMS)
Create “virtual lesions” with electrical coils with a magnetic field aiming
towards scalp, overstimulating small areas in the brain which creates
temporary lesions that can help neuro research
Wilder Penfield – neurosurgeon in Canada, mainly Montreal
Famous for brain surgery on epileptic patients
Direct stimulation – stimulate areas before getting rid of epileptic areas in
surgery while the patient was awake – some patients even smelled burnt toast
Mapped brain areas using direct stimulation that are still used today with
almost no change despite being created 70 years ago
Single cell recordings – plant recording device in cell, manipulate stimuli to
record the cell’s response to that stimuli
CT/CAT – Computer Axial Tomography
Uses x-rays shot at different angles, working in unison with x-ray detectors, to get a
picture of what’s inside body
Measures amount of x-rays absorbed by your head
Different tissues absorb x-rays at varying degrees
Computer analyzes intensity of the x-rays as they leave the body and produces a
Magnetic Resonance Imaging
Large magnetic field
Earth magnetic field = .000005 Tesla
MRI = 4 Tesla
That is 800,000 times greater
Radio wave pulses shot at head
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