Research Methods

Research Methods

1. Experimental Ablation

   • Stereotaxic Surgery
     • Brain surgery using a stereotaxic apparatus to position an electrode or cannula in a specified position of the brain
   • Excitotoxic Lesions
     • inject a glutamate agonist into specific part of the brain
   • Electrolytic/radio frequency lesions
     • Burning a hole in the brain
   • 6-hydroxydopamine (6-OH-DA)
     • Specific chemical lesions
       • Poison for dopamine neurons
   • Can be used for chemotherapy/radioactive therapy/removal of tumors
   • Histological Methods
     • Gross Disection
       • Only able to identify areas of fats
     • Microscopic Analysis
       • 1. Preservation of tissue (Perfusion) using Formalin
         • 2. Cut the tissue, usually to freeze using Microtome
           • 3. Stains
             • Golgi
               • Able to see 1% of neurons
             • H&E
               • Standard stain for pathology
                 • Able to identify if tumor is malign or benign
                   • Sudan Black: Stains fat
             • Cresyl Violet
               • Most common stain for NS
                 • Nissyl Stain allows you to see all cells (especially nucleus) but only part of them
                   • Unable to differentiate nucleus from glia.
                 • Good for comparing number of cells
         • Formalin hardens brain

2. Immunocytochemistry

   • Takes advantage of the body's immune reaction
   • Use immunocytochemistry to look for the enzyme that makes the antibody to find the proteins
   • Fluorogold
     • Retrograde Label
       • Injected into striatum & taken up by terminal buttons and carried back to the cell bodies.
         • Afferent
   • PHA-L
     • Anterograde Label
       • injected into substantia nigria through stereotaxic surgery and gets transported from cell body to terminal
         • Anterograde Transport
         • Efferent

3. Studying the Living Brain

   • CAT/CT
     • For aneurysms/stroke damage
     • Contrast Dye (Opaque)
       • Able to be injected anywhere via IV
   • MRI
     • Soft tissue damage, best for corpus callosum study
       • Only able to detect if bigger than 5mm
       • Gross structure of brain
     • Looks for changes in hydrogen atoms (water)
   • fMRI
     • To look at neural activity
       • Detects changes in blood oxy levels
   • PET
     • To detect radioactivity in brain
       • to be injected with a radioactive drug that binds to a receptor to locate the receptors.
         • Cocaine decreases the amount of radioactivity (less glucose taken up, less active)
     • 2-DG (de-oxyglucose) labeling (radioactive)
       • Attaches to neurons

4. Phineas Gage

   • Explosion incident pierced a hot rod through his skull
     • Behaviour changed drastically after incident
     • Frontal Lobe destroyed

5. Lobotomy

   • Invented in 1935 by Egos Moniz for chimpz
   • Popularized by Walter Freeman in the US mid 1930s
     • On autistic/schizophrenic patients
   • Orbidofrontal (small part of prefrontal cortex) destroyed
     • Supposedly turned some people docile, but destroyed other functions too