Objective: It has been shown that discharge of single darkness detector in the frog retina can lead to suprathreshold excitation of the tectal neurons. The present study was designed to explore whether a suprathreshold excitation of frog tectal neurons can be elicited by the discharge of single moving-edge detector.
Material and methods: The discharge of a single retina ganglion cell was elicited by the electrical stimulation. The evoked electrical activity of the tectal neurons was recorded by the carbon-fiber microelectrode brought into the optic fiber layer F.
Results: The obtained data have suggested that a discharge of a single retinal moving-edge detector elicits a suprathreshold excitation of tectal neurons. The suprathreshold excitation of the tectal neurons is achieved due to the frequency facilitation of the fast retinotectal synaptic potentials.
Conclusions: Results of the present study suggest that activation of moving-edge detector gives rise to the same effects as the activation of the darkness one. However, the stronger excitation (the longer volleys of action potentials) for the moving-edge detector is needed to evoke suprathreshold excitation of tectal neurons compared to the darkness one. This difference could be caused by a lower quantal size of neurotransmitter release in synapses of the retinotectal input from the moving-edge detector than from the darkness one.