[Changes in the duration of action potentials of functionally different Helix neurons in response to serotonin].

Bath application of serotonin was studied for its effect on the duration of action potentials in sensory neurons, interneurons and motoneurons participating in avoidance behaviour of snail. Serotonin application increased the action potential duration in sensory neurons, while in interneurons and motoneurons such changes were absent. An increase of the action potential duration in sensory neurons can be the mechanism of the EPSP amplitude increase recorded in interneurons during application of serotonin. Functional consequences of selective reactions in neurons with different functional role are discussed.