Аннотация:Response of the brain to the single sensory stimuli lasts about second. This period compound potentials and responses of neurons might be recorded, when connections within brain are changing. The change during response to a single stimulus has been named immediate plasticity [11]. The paper presented devotes to the investigations of immediate plasticity by simultaneous intracellular recording of electrical activity synaptically connected identified neurons of the snails Helix pomatia and Helix lucorum.