PSYCO104 Lecture Notes - Lecture 4: Diffusion Mri, Infrared Spectroscopy, Pulse Oximetry

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PSYCH 104 – Lecture 4 – Biological Psychology and Genetic Influences
Diffusion Tensor Imaging (DTI):
Relatively new
Based on MRI taking different types of images of the brain measuring the
diffusion of the water in the neural tissue
oAllows for fine, precise detail about the structures
oDownside: Expertise is hard and more expensive
Functional Magnetic Resonance Imaging (fMRI):
Repeated cycles of measuring and detecting changes in the blood and
oxygenation of the brain
oWhen the brain is used it needs more oxygen
Make people do different cognitive tasks (ex. get people to sing,
solve problems, do math) during scanner
Observe the changes and see which parts are being used for
each task
Disadvantage: Stay in these machines for a long time (bad for people who are
claustrophobic), the time course is limited to how quickly the image gets
processed to assess the brain
Near Infrared Spectroscopy (NIRS):
Infrared lights pointed towards the skull
oShine lights into the brain
Receptors on them (refracted infrared lights come back)
oMore oxygenated blood (more refraction than deoxygenated blood)
Can get a pattern of activation of the brain
Time course is good (measures pretty quickly for the changes and the refractions
happening)
oCan get a clear idea of where the refracted lights are coming from
Downside: you can only measure the cortical levels (the outside portions) such
as the cerebrum
oDoesn’t penetrate and is not precise enough to judge activity levels
Electroencephalography (EEG):
As neurons fire, there will be a change in electrical activity that the sensors can
detect, can get the measure of neural activation
oDownside: only get measure of the electrical change for cortical
structures
Generalization: precision is limited (gaps between each recorder)
o256 electrodes (time course is the best)
Measured in milliseconds or even less
Can see the quick changes in impulses and activity
Intracranial EEG
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oTakes recordings of the electrical impulses directly inside the brain
oElectrodes implanted into different brain structures
oNot done for experimental purposes
oRecording the medical issue an individual is having
Ex. Epileptic seizures (early monitoring system to know when they
will have a seizure)
Can record the data and get more precise data (the signal
won’t be disturbed)
Magnetoencephalography (MEG):
Very expensive
Uses a device called SQUID:
oMachine measures slight changes in magnetic potential within the brain
while it is functioning
oUses it to reconstruct an image of activation
Fast time course (10 milliseconds)
Downside: can only use this for cortical activity (surface levels of the brain)
oStrength between two magnets (gets weak when distance is too far)
Transcranial Magnetic Stimulation (TMS):
Assess brain function and the roles
Wave the “TMS” wand over an individual’s head (magnetic field that disrupts the
activation around the area)
oReduces coherent signal
oSending neurons into a haywire state
Observe the changes in behavior (ex. Can’t speak)
Regions of the Brain:
Forebrain
Midbrain
Hindbrain
oNames are based off of how the embryo was developed
Hindbrain:
Made up of the:
oBrainstem
oMedulla
oPons
oCerebellum
Controls the primitive level of functioning
Structures automate the body’s processes
Brainstem:
oA lot of major neuron tracts and motor tracts continuing down to the spinal
cord
oContains many of the basic life support systems
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Ex. Respiration, when the heart should beat, when to breathe,
lungs expand, etc.
oLook at this amount of activity to see if someone is “alive”
Not much activation in this area for more than 12 hours (claimed
as brain-dead)
No signals from the brain back to the body (no processing is
occurring)
Medulla:
oControls functions (sends the signals to the parts of the body that are
essential to survival)
oAffected by alcohol drastically
Suppresses activation of the medulla
Alcohol poisoning (shuts down the medulla)
oBreathing and heart beating can’t take place
because of severe alcoholism
Pons:
oNeural fibers cast from the lower centre to the higher centre
Pons act as the bridge
oClusters of neurons responsible for sleep and dreaming
Damage to the pons will result in a coma
Cerebellum:
oCan damage the cerebellum because it won’t be critically important for
necessary life functions
Responsible for involuntary motor movements
Damage: jerky movements, inability to perform walking,
multiple sclerosis (MS)
oDisrupted by alcohol
The more alcohol consumed the more and more uncoordinated
Precise timing of neuron firing is disrupted
Midbrain:
Relay the lower centres to the higher areas that are critical to interpret the signal
(complex thought)
Reticular formation (can be in all parts of the brain, but mostly in the midbrain)
Gray matter, red nucleus, substantia nigra, and ventral region (important for
voluntary control)
Reticular formation:
oSensory system (alerts the brain that messages are coming)
Allows or blocks the messages to go to higher centres
Transmit messages down into the lower portions of the brain and
body
Allows us to be consciously aware of our existence
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Document Summary

Psych 104 lecture 4 biological psychology and genetic influences. Functional magnetic resonance imaging (fmri): repeated cycles of measuring and detecting changes in the blood and oxygenation of the brain, when the brain is used it needs more oxygen. Make people do different cognitive tasks (ex. get people to sing, solve problems, do math) during scanner. Infrared lights pointed towards the skull: shine lights into the brain. Receptors on them (refracted infrared lights come back: more oxygenated blood (more refraction than deoxygenated blood) Can see the quick changes in impulses and activity. Intracranial eeg: takes recordings of the electrical impulses directly inside the brain, electrodes implanted into different brain structures, not done for experimental purposes, recording the medical issue an individual is having. Epileptic seizures (early monitoring system to know when they will have a seizure: can record the data and get more precise data (the signal won"t be disturbed)

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