[Discharges of neurons of the frog tectum during electric stimulation of individual retinal ganglion cells].

In the frog optic tectum, at the depth of 200-270 micron extracellular monosynaptic PSPS of one axon were recorded under threshold electrical stimulation of the retina by a short train of stimuli. The latency of presynaptic spike was 8-12 ms. At a 5-25 ms interval between successive stimuli a negative spike was observed on the top of the testing EEG quanta enlarged 1.5-2.5 times. This spike is considered to be a population discharge evoked by the firing of a single fibre of the optic tract. This fibre terminates in layer F or G, while the population spike is generated by the tectum units of layers 6-8. A possibility that the firing of the 3d-5th class detectors excites tectal ganglionic cells whose axons form the main part of the tectobulbospinal tract is discussed.