Adult Zebrafish Electrophysiology: A Method to Measure the Extracellular Electrical Activity of Neurons In Vivo

Abstract

Source: Johnston, L., et al. Electrophysiological Recording in the Brain of Intact Adult Zebrafish.  J. Vis. Exp. (2013)

The protocol describes the procedure to perform electrophysiology in adult zebrafish. This method can be used for measuring neural activity in vivo.

Protocol

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.

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Habitat water			pH 7.0-7.4, conductivity of 400-450 μS;  maintained by Instant Ocean and Sodium Bicarbonate
0.4% Tris-Buffered Tricaine	Sigma-Aldrich	E10521	pH 7.2-7.4; stored at -20 degree C
60 ml Luer lock syringe tubes	Becton, Dickinson and Company	309653
3-way Stopcocks with Luer connections
0.010 in Silver wire	A-M Systems, Inc.
Q-series electrode holder
Fisherbrand 100 mm x 15 mm Petri dish	Fisher Scientific	NC9299146
34 G Beveled needle	World Precision Instruments, Inc.	NF34BV
37 cm x 42 cm Kimwip	Kimberly-Clark Professional	TW31KEM
1/8 in diameter tube
1 mm diameter tube
Microscope (Leica MZ APO)	Another microscope can be used