Dynamic analysis of electrically coupled neurons in Helisoma Trivolvis

A theoretical treatment has been combined with practical methods to obtain quantitative measurements from the transient responses of electrically coupled cells. Communication via electrical synapses is characterized as a low resistance pathway, whereas membrane response is represented by a resistance in parallel with a capacitance.The validity and consequences of this model have been investigated using data from identified pairs of electrically coupled neurons in the freshwater snail, Helisoma trivolvis. An automated procedure has been developed to monitor the degree of coupling over extended periods of time and transform these measurements into equivalent electrical units.The model has been used to: functionally assess the coupled system employing a single micropipette; provide a spatial profile of cell load; monitor induced changes in coupling; examine the role of coupling in controlling the rate of spread of excitation; and evaluate electrical changes which occur within cells during axonal injury and subsequent recovery