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

- Neurons propagate electrical impulses via action potentials. When the neuron is in resting state, there is a slower outflow of potassium ions than the inflow of sodium ions, which leads to the change in membrane potential. This causes the sodium ion channels to open and allow the inflow of sodium ions, generating an electrical impulse.

The method of studying such activities in a cell is called electrophysiology. Begin the procedure by inserting a secondary electrode tip into the nostril of an adult zebrafish. Next, insert the primary electrodes superficially, within the exposed optic tectum, to measure extracellular neural activity.

The primary electrode measures the extracellular membrane potential of all cells surrounding it. The signal represents the combined membrane potential of all these cells. The electrode detects the signal and transmits it to an amplifier-- an oscilloscope-- which presents a visual display of the membrane potential, and a computer.

Observe the readings and analyze the electrical difference between the primary and the secondary electrodes. The electrophysiological measurement is a comparison. In the example protocol, we will measure the effect of pharmac