ABSTRACT
Gap junctions mediate the electrical communication between neurons by providing a pathway of low resistance for the spread of the electrical currents between coupled cells. This chapter describes the necessary steps that make possible the monitoring of electrical transmission in living fish. This in vivo approach provides the opportunity of exploring the properties of neuronal gap junctions in a more natural context under which the anatomical connections and the higher regulatory systems are preserved. The Mauthner cells are a pair of unusually large reticulospinal neurons located in the medulla of fish. The morphological characteristics of both the auditory afferents and the Mauthner cells make the use of the whole-cell voltage clamp technique impractical to estimate the junctional conductance. The microelectrode is lowered into the Artificial cerebrospinal fluid (aCSF) and its impedance monitored on a computer screen or an oscilloscope by applying 1 nA current pulses.
