[Synaptic effects induced in lamprey motor neurons by direct stimulation of individual presynaptic fibers].

Parallel intracellular recording from giant reticulospinal axons and target motoneurons of the lamprey (Lampetra fluviatilis) revealed unitary synaptic actions produced in the post-synaptic membrane by direct stimulation of individual presynaptic fibres. It is shown that monosynaptic reticulomotoneuronal EPSPs contain both electrical and chemical components which have different synaptic delay, time course, amplitude, sensitivity to Cadeficit and operating characterisitcs. A single motoneuron may receive direct electrotonic inputs from several giant axons. Individual giant axons may affect segmental motoneurons not only via monosynaptic connections but also via additional synaptic relays.