Psych 3L03 Neuroscience Laboratory

PROJECT 1: BRAIN MECHANISMS FOR SKILL LEARNING

LECTURE AFTER THE EXPERIMENT

Selected information for the METHOD of OUR CURRENT PROJECT

Method: subject, apparatus, procedure

  1. SUBJECTS:
    1. Long-Evan hooded rats, male, N=4+2, body weight 250-300g
    2. care: 12:12 light-dark cycle, food (deprived), water
  2. APPARATUS:
    1. Box: 65x15x80cm Plexiglas box
    2. slit opening: ~ 1.5 cm
    3. plat form: 2 x 4 cm
  3. PROCEDURE:
    1. Training:
      1. task
      2. using preferred paw
      3. 5 days, 50 minutes each
      4. movement classification
      5. time interval between reaches
    2. Recording:
      1. done 24 hrs after the last training session
      2. anesthetize rat with sodium pentobarbitol at 60 mg/kg body weight
      3. open scalp to expose skull surface
      4. determine location of bregma
      5. coordinates:
        1. recording AP1.6 mm, ML2.0 mm, Depth 0.4 mm
        2. stimulating AP1.6 mm, ML2.5 mm, Depth 0.4 mm
      6. mark skull surface over forelimb region of motor cortex and drill holes to expose brain
      7. position electrodes on surface of brain and lower 400 mm into layer 2/3
      8. Using two bipolar electrodes: one for stimulating and one for recording. Both are constructed from stainless steel wire insulated with teflon
      9. record field potentials evoked at different intensities of stimulation to construct input/output function.
        1. A Grass Instruments stimulator is used to deliver the stimulation.
        2. Stimulation consists of a biphasic square pulse that is 100 msec in duration.
        3. Seven intensities (mA) are used: 63, 100, 159, 398, 631, 798, 1000
      10. The evoked field potential is amplified (x2000) by a Grass Instruments amplifier and digitized by a National Instruments analog to digital converter. The digitized data is viewed and stored on the computer by LabView software.  The Labview output of response amplitude was calibrated and displayed in the unit of mV. 
    3. Histology
      1. Following the recording the rat is perfused with 10% formalin and the brain is sectioned on a cryotstat and stained with cresyl violet to verify the placement of the electrodes (this wasn't actually done but should have been).