Cognitive Neuroscience Techniques

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COGNITIVE SCIENCE 17 Peeking Inside
The Head Part 1 Jaime A. Pineda,
Ph.D.
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Imaging The Living Brain

• Computed Tomography (CT)
• Magnetic Resonance Imaging (MRI)
• Positron Emission Tomography (PET)
• Functional MRI (fMRI)
• Electroencephalography (EEG)
• Magnetoencephalography (MEG)

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CT Scans(1970s)

• X-ray scanner rotated 1o at a time over 180 o
• Contrast agent
• Computer reconstruction
• Horizontal sections
• Reveal structural abnormalities, such as cortical
  atrophy or lesions caused by a stroke or trauma.

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Computerized Axial Tomography
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MRI Scans(1980s)

• A strong magnetic field (10-30k X) causes
  hydrogen atoms to align in the same orientation.
  
• When a radio frequency wave is passed through the
  head, atomic nuclei emit electromagnetic energy
  (NMR) as they relax.
• The MRI scanner is tuned to detect radiation
  emitted from the hydrogen molecules.
• Different types of tissue produce different RF
  signals
• Computer reconstructs image.

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MRI vs. CT Scans

• Advantages of MRI
• No ionizing radiation exposure
• Better spatial resolution
• Horizontal, Frontal or Sagittal planes
• Disadvantages
• Cost
• No metal!
• noisier

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Hemodynamic Techniques

• Oxygen and glucose are supplied by the blood as
  fuel for the brain
• The brain does not store fuel, so
• Blood supply changes as needs arise
• Changes are regionally-specific following the
  local dynamics of neuronal activity within that
  region
• These techniques show where functional activity
  occurs

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PET Scans

• A positron emitting radionuclide is injected
  (e.g., 2-deoxyglucose,
• 15O radioactive oxygen).
• Positrons interact with electrons which produce
  photons (gamma rays) traveling in opposite
  directions.
• PET scanner detects the photons.
• Computer determines how many gamma rays from a
  particular region and a map is made showing areas
  of high to low activity.
• 10 mm resolution invasive

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What PET Can Do
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PET vs. CT Scans

• CT images brain structure.
• PET images brain function.
• CT involves absorption of X-rays.
• PET involves emission of radiation by an injected
  or inhaled isotope.

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Functional MRI (fMRI)(1990s)

• Images brain hemodynamics
• Blood oxygen level dependent (BOLD) signal
• Advantages over PET
• No injections given
• Structure and Function
• Shorter imaging time
• Better spatial resolution
• 3-D images
• Check out this website for more info on fMRI
  methods http//www.fmri.org/fmri.htm

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Brain Regions Impaired by Alcoholism
Non alcoholic
Alcoholic
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Psychophysiology

• Electroencephalography (EEG)
• Electromyography (EMG)
• Electrooculography (EOG)
• Electrodermal activity (Skin Conductance)
• Cardiovascular activity
• Heart rate (EKG)
• Blood Pressure
• Plethysmography

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Seizure
Normal
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Signal Averaging
Event-related Potentials (ERPs)

• Background EEG signal can be removed by
  trial-averaging revealing the response of a brain
  region to stimuli

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Electroencepholography

• Non-invasive
• High temporal resolution
• Direct reflection of neuronal activity
• Less expensive than fMRI or PET
• Poor spatial localization due to recordings made
  at the scalp
• Better suited to answering questions about when
  cognitive processes work not where they work

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Transcranial Magnetic Stimulation

• Coil placed over target brain region
• Cognitive failures recorded

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Techniques Used With Nonhuman Animals

• Stereotaxic Surgery
• Lesion Methods
• Electrical Stimulation
• Electrophysiological Recording

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Lesioning Techniques

• Aspiration lesions
• Radio-frequency lesions
• Knife cuts
• Cryogenic blockade
• Chemical Lesions

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Neurohistology Techniques

• Fixation, preservation of tissue, sectioning and
  staining of tissue
• Uses of histological techniques
• Confirming lesion sites or electrode locations
• In combination with neural tracing techniques
  (anterograde, retrograde labeling)
• Autoradiography or Immunohistochemistry

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Neurohistology Techniques

• Nissl Stains
• e.g., cresyl violet
• cell bodies
• Golgi Stain
• whole neurons
• Myelin Stains
• myelin
• For more info., see web site
• http//education.vetmed.vt.edu/Curriculum/VM8054/L
  abs/Lab9/Lab9.htm

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Electrophysiology Techniques

• Intracellular unit recording
• Extracellular unit recording
• Multiple-unit recording
• Patch clamping

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Pharmacological Methods

• Measuring Chemical Activity
• 2-DG Autoradiography
• In vivo microdialysis
• Localizing Neurotransmitters and Receptors
• Immunocytochemistry
• In situ hybridization

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Genetic Engineering
Transgenic mice

• Gene Knockout Techniques
• Gene Replacement Techniques

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Behavioral Research Methods

• NEUROPSYCHOLOGICAL TESTING
• Intelligence (e.g., WAIS, WISC)
• Verbal Subtests
• Information, digit-span, vocabulary, arithmetic,
  comprehension, similarities
• Performance Subtests
• Picture-completion, picture-arrangement, block
  design, object assembly, digit-symbol substitution

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Neuropsychological Testing

• Language (lateralization)
• Sodium amytal test
• Dichotic listening test
• Language deficits
• Phonology
• Syntax
• Semantics

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Neuropsychological Testing

• Memory
• STM, LTM
• Explicit, Implicit
• Semantic, Episodic
• Frontal Lobe Function
• Wisconsin Card Sorting Task

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Animal Behavior Paradigms

• Species-common behaviors
• Aggressive Behaviors
• Defensive Behaviors (e.g., anxiety paradigms)
• Reproductive Behaviors
• Locomotor Activity
• Traditional Conditioning Paradigms
• Pavlovian (Classical) Conditioning
• Operant Conditioning

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Animal Behavior Paradigms

• Open Field Apparatus

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Animal Behavior Paradigms

• Operant Conditioning Apparatus

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Animal Behavior Paradigms

• Common Learning Paradigms
• Conditioned Taste Aversion
• Conditioned Avoidance
• Radial Arm Maze
• Morris Water Maze
• Conditioned Defensive Burying

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Animal Behavior Paradigms

• Radial Arm Maze