1. Electrophysiology

1. Shut off the intubation stop-cock and quickly disconnect the Luer lock connecting the intubation base to the tricaine drip.
   1. Move the intact intubation setup to the electrophysiology microscope and connect to the perfusion system.
   2. Turn on the habitat water and perfuse at a rate of 1 ml/min for ~1 hr, in order to wash out the tricaine.
2. Using a micromanipulator under visual control, position the secondary electrode so that the electrode tip can be inserted into the animal's nostril or into the dip behind the upper jaw.
3. Insert the primary electrode needle into the craniotomy opening. Insert the needle into the tissue, such that the tip is positioned fairly superficial within the optic tectum.
   1. If the electrode is too deep, the electrical signal may be small.
4. Collect and analyze the electrical difference recorded between the primary and secondary reference electrodes. This process will allow for extracellular recordings to be obtained.
   1. Collect the data in Gap-free mode at a 5 kHz sample rate, with a low pass filter of 0.1 kHz and a high pass filter of 1 Hz.
   2. Do not begin recording electrophysiological activity until habitat water has perfused for a minimum of 45 min.
   3. Record a baseline of native activity for at least 15 min prior to the addition of experimental drugs. Begin perfusion with experimental drugs of choice and record for the desired amount of time. In healthy preparations, it is possible to record the neurological activity for 2-3 hr.