Regional variations in excitability of barnacle neurons

摘要: Optical recording techniques using voltage-sensitive dyes were used to examine the initiation and propagation of action potentials within neurons supraesophageal ganglion giant barnacle, Balanus nubilus. When a neuron was stimulated with current injection into soma, site spike initiation, determined as location earliest time-to-peak, usually in axon, 100 200 micron from soma. The soma broader often later, suggesting that cell body less excitable than axon. potential narrowest at then widened before propagating uniformly down In most cases, somatically electrotonic pulses propagated dendrites little delay or change shape, indicating length these processes great. Several different kinds experiments indicated some cells are excitable. These included observations (a) spikes could be made initiate earlier axonal region which they connected, (b) sometimes decremented subthreshold along dendritic processes. However, other cases decline amplitude widening demonstrated passive dendrites, not all equally