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Techniques to Learn about the Brain and Neural Function

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Gunshot wounds, tumors, strokes, Alzheimer s disease Korsakoff s Syndrome: caused by B1 deficiency related to malnutrition or alcoholism – PowerPoint PPT presentation

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Title: Techniques to Learn about the Brain and Neural Function


1
Techniques to Learn about the Brain and Neural
Function
  • Studying patients with brain damage linked loss
    of structure with loss of function
  • Phineas Gage
  • http//www.youtube.com/watch?v9QXI_BxlY7M
  • Paul Broca and Carl Wernicke
  • Gunshot wounds, tumors, strokes, Alzheimers
    disease
  • gtKorsakoffs Syndrome caused by B1 deficiency
    related to malnutrition or alcoholism

2
Lesions damaging the structure
  • Allows study loss of function
  • Ablation removal of the structure
  • Vast majority of lesion studies are with lab
    animals, work is determined by Animal Care and
    Use Committees

3
Organization and Evaluation of Brain Function
  • http//www.learner.org/resources/series142.html?po
    pyespid1569

http//www.learner.org/resources/series142.html?po
pyespid1569
4
Direct electrical stimulation provides another
way to test brain function
  • EEG (electroencephalogram) amplified tracing of
    activity of a region of the brain produced when
    electrodes positioned in direct contact with the
    scalp transmit signals about the brains
    electrical activity to an EEG machine

5
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7
EEG
  • Used to study epilepsy
  • Present stimulus repeatedly to a subject and have
    it filter out activity unrelated to the stimulus
  • conclusion identification of electrical wave
    evoked by the stimulus
  • Ex we can detect where information goes in a
    cats brain when its whiskers are stroked

8
Imaging Techniques Provide Images of Brain
Anatomy (CAT/CT and MRI)
9
CAT Scan/CT Scan (computerized axial tomography)
  • CAT scan creates computerized image of X-rays
    passed through brain
  • Creates 2D slices
  • Arranged to show extent of a lesion

10
CAT Scans
  • 2. Procedure may involve injection of contrast
    dye
  • Shorter scanning periods than MRI (no magnets
    used)
  • Used for patients with pacemakers and metallic
    implants

11
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12
MRI (magnetic resonance imaging)
  • Giant circular magnet causes hydrogen nuclei in
    the water of cells to orient in a single
    direction
  • Pulses of radio waves cause atoms to spin at a
    frequency
  • Computer constructs images based on these signals
  • MRI images more detailed than CAT or PET scans
  • Can be produced for any plane of view

13
MRI produces the most detailed picture of brain
structure 3D
14
Some imaging techniques have enabled
neuroscientists to observe activity of the brain
as it functions.
  • fMRI (functional magnetic resonance imaging)
  • PET scans (positron emission tomography)

15
fMRI
  • Capitalizes on MRI ability scanners to detect
    changes in oxygen during heightened neural
    activity
  • Heightened activity more oxygen used by brain
  • fMRI preferred to PET b/c it doesnt expose brain
    to radioactivity
  • Magnetic fields pose mild risk, if overused

16
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17
PET Scans (positron emission tomography scan)
  • Ready for this? Here goes
  • When neurons are active, automatic increase in
    blood flow to active regions of the brain bring
    oxygen and glucose necessary for respiration
  • Blood flow changes are used to create brain
    images when tracers (i.e. radioactively labeled
    glucose) injected into the blood of the subject
    emit particles called positrons
  • Positrons are then converted into signals
    detected by PET scanner
  • In other words, the positrons almost immediately
    are destroyed and produce pairs of gamma
    particles, and the gamma radiation is detected by
    the scanner
  • Glucose concentrates in the areas of greatest
    activity and the concentration of labeled
    substances taken up by the brain tissue
  • Revealed in colored computer graphics
  • This all depends on the amount of metabolic
    activity in the imaged brain region
  • This technique tracks complex series of
    interactions in different brain areas associated
    with specific mental processes
  • 2. PET scans expose subject to radioactivity

18
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19
Other advances allow neuroscientists to learn
about relationship of neurological function to
behavior
  • BEAM brain electrical activity mapping
  • Feeds EEG information from numerous recording
    sites more accurate diagnoses of tumors,
    epilepsy, and learning disorders
  • B. MEG magnetoencephalogram
  • C. SQUID superconducting quantum interference
    device
  • Sensitive devices to detect magnetic fields
  • D. PRONG parallel recording of neural groups
  • E. TMS transcranial magnetic stimulation
  • F. Gene knock out technology (removal of specific
    genes from mice)

20
How well did you do? 1999 AP Exam 79
  • Which of the following is a brain-imaging
    technique that produces the most detailed picture
    of brain structure?
  • a. Electroencephalography (EEG)
  • b. Magnetic resonance imaging (MRI)
  • c. Positron emission tomography (PET)
  • d. Computerized axial tomography (CAT)
  • e. Electromyography (EMG)

21
I think my hyperactive 5 year old may have ADD.
To make sure that he is in fact suffering from
Attention Deficit Disorder and not epilepsy,
doctors would most likely use which machine to
conduct the necessary tests using strobe lights?
  • a. MRI
  • b. CT
  • c. PET
  • d. EEG
  • e. fMRI

22
If while in an experiment where I am asked to
select and defend some options, I am told that,
Hypothetically, if we were to deceive you, would
you be deceived? and I answer that I would know
if I was being deceived and then they deceived
me anyway and I did NOT notice it all, I would be
exhibiting
  • a. Hindsight bias
  • b. Confirmation bias
  • c. Change blindness
  • d. Choice blindness
  • e. Choice-blindness blindness
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