[Electrotonic excitatory postsynaptic potentials evoked by stimulation of ventral roots in motoneurons and Muller axons of Lampetra fluviatilis lampreys].

In experiments on isolated spinal cord of the lamprey, during stimulation of the ventral roots, excitatory postsynaptic potentials (EPSP) in motonuerons and Muller axons were recorded which are stable to the abssence of Ca and the presence of Mg in the perfusion fluid. With the increase in stimulation the EPSP gradually increased, persisting after the subtraction of extracellular field from the recorded intracellular response. The results obtained demonstrate that in the lamprey excitation may be transmitted electrotonically from activated motoneurons to the adjacent ones and to Muller axons. It is suggested that neighbour motoneurons interact via electric synapses which are formed by the returning collaterals of motor axons and by motoneurons, as well as via dendro-dendritic contacts.