Chapter 5: Methods

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Chapter 5 Methods
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Overview of Lecture

• Experimental Ablation
• Recording and Stimulating Neural Activity
• Neurochemical Methods
• Genetic Methods
• Behavior

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The Goals of Physiological Psychology

• Identify
• Neural systems that control discrete behaviors
• Understand
• The physiological bases of behavior
• Genes
• Neurons
• Transmitter/peptide systems
• Systems of neurons

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Central Nervous System Approaches

• Ablation
• Electrolytic lesions/RF lesions
• Chemical lesions
• Aspiration
• Knife cuts
• Temporary blockade
• KCl (spreading depression)
• Colchicine (slows down axoplasmic transport)
• Cryogenic cooling

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• Experimental Ablation
• Stereotaxic surgery
• Stereotaxic surgery
• Brain surgery using a stereotaxic apparatus to
  position an electrode or cannula in a specified
  position of the brain.
• Bregma
• The junction of the sagittal and coronal sutures
  of the skull, often used as a reference point for
  stereotaxic brain surgery.
• Ablation

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The Stereotaxic Instrument

• Allows for precise manipulation of sub-cortical
  structures
• Instrument involves 3 dimensions
• Stereotaxic Atlases
• For many species rats to humans

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Anatomical Techniques

• Histological Techniques
• Perfuse (to remove blood from brain)
• Remove brain
• Fix to solidify brain material (prevent
  autolysis)
• Section brain into thin slices (50-80 microns) ,
  microtome
• Use stains to highlight selective neural elements
• Myelin (Weil stain)
• Cell body (cresyl violet Nissl substance in
  cytoplasm)
• Membrane (Golgi stain)

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• Histological Methods
• Electron microscopy
• Scanning electron microscope
• A microscope that provides three-dimensional
• information about the shape of the surface of a
  small object.

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• Tracing Neural Connections
• Tracing efferent axons
• Anterograde labeling method
• A histological method that labels the axons and
  terminal buttons of neurons whose cell bodies are
  located in a particular region.
• PHA-L
• Phaseolus vulgaris leukoagglutinin a protein
  derived from kidney beans and used as an
  anterograde tracer taken up by dendrites and
  cell bodies and carried to the ends of the axons.

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• Tracing Neural Connections
• Tracing efferent axons
• Immunocytochemical method
• A histological method that uses radioactive
  antibodies or antibodies bound with a dye
  molecule to indicate the presence of particular
  proteins of peptides.

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Immunocytochemistry

• Pituitary cells
• Dual label for Growth Hormone (GH)
• Black GHRH
• Orange GH antigen

SourceL http//cellbio.utmb.edu/ childs/cytochem.h
tm
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• Tracing Neural Connections
• Tracing afferent axons
• Retrograde labeling method
• A histological method that labels cell bodies
  that give rise to the terminal buttons that form
  synapses with cells in a particular region.
• Fluorogold
• A dye that serves as a retrograde label that is
  taken up by the terminal buttons and then carried
  back to the cell bodies.

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• Tracing Neural Connections
• Tracing afferent axons
• Pseudorabies virus
• A weakened form of a pig virus used for
  transneuronal tracing which labels a series of
  neurons that are interconnected synaptically.
• This method permits anterograde and retrograde
  directions.

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• Study of the Living Human Brain
• Computerized tomography (CT)
• The use of a device that employs a computer to
• analyze data obtained by a scanning beam of
  X-rays
• to produce a two-dimensional picture of a slice
  through the body.

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• Study of the Living Human Brain
• Magnetic resonance imaging (MRI)
• A technique whereby the interior of the body can
  be accurately imaged involves the interaction
  between radio waves and a strong magnetic field.

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Electrical Recording

• Patch-clamp
• Intracellular
• Suction electrode-photoreceptors
• Single-unit
• Multiple unit
• Gross potentials

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• Recording and Stimulating Neural Activity
• Magnetoencephalography
• A procedure that detects groups of synchronously
  activated neurons by means of the magnetic field
  induced by their electrical activity.
• This procedure uses an array of superconducting
  quantum interference devices, or SQUIDS.

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• Recording the Brains Metabolic and Synaptic
  Activity
• 2-deoxyglucose (2-DG)
• A sugar that enters cells along with glucose but
  is not metabolized.
• Autoradiography
• A procedure that locates radioactive substances
  in a slice of tissue the radiation exposes a
  photographic emulsion or a piece of film that
  covers the tissue.

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• Recording the Brains Metabolic and Synaptic
  Activity
• Fos
• A protein produced in the nucleus of a neuron in
  response to synaptic stimulation.
• Positron emission tomography (PET)
• The use of a device that reveals the localization
  of a radioactive tracer in a living brain.
• Functional MRI (fMRI)
• A modification of the MRI procedure that permits
  the measurement of regional metabolism in the
  brain.

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• Measuring the Brains Secretions
• Microdialysis
• A procedure for analyzing chemicals present in
  the interstitial fluid through a small piece of
  tubing made
• of a semipermeable membrane that is implanted in
• the brain.

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• Behavioral Effects of Electrical Stimulation
• Transcranial magnetic stimulation (TMS)
• Stimulation of the cerebral cortex by means of
  magnetic fields produced by passing pulses of
  electricity through a coil of wire placed next to
  the skull interferes with the functions of the
  brain region that is stimulated.

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• Neurochemical Methods
• Organophosphate insecticides
• Human exposure to insecticides that contain
  acetylcholinesterase inhibitors (acetylcholine
  agonists) could cause intense, bizzare dreams and
  walking hallucination.

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• Genetic Methods
• Targeted mutations
• A mutated gene )also called a knockout gene)
  produced in the laboratory and inserted into the
  chromosomes of mice fails to produce a
  functional protein.
• Antisense oligonucleotide
• A modified strand of RNA or DNA that binds with a
  specific molecule of messenger RNA and prevents
  it from producing it particular protein.

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Behavioral

• Detection
• Discrimination
• Cognitive Performance
• Motor Performance

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