Propagation of Voltage Transients in Arborized Neurites of Retzius Cells of the Leech in Culture

Abstract

Abstract Propagation of electrical signals is studied in Retzius cells of the leech in culture using voltage-sensitive fluorescent dyes at a spatial resolution of 8 × 8 μm2 and 14×14 μm2 and at a sam pling interval of 0.12 ms. The neurons are stimulated by a microelectrode impaled in the soma. Action potentials of a halfwidth of 2 -3 ms are triggered close to the end of the primary neurite dissociated from the leech. They propagate back to the soma at invariant halfwidth at a veloci­ ty of 50-230 μm/ms. They pervade extended arborized secondary neurites which are grown on extracellular matrix protein. Their width is enhanced up to a factor two. The velocity is around 100-150 μm/ms such that delays up to 3.5 ms are observed. Accordingly the neuritic trees are not isopotential. The features of propagation are found to be incompatible with passive spread.