Electrophysiology of the Insect Dorsal Ocellus : III. Responses to flickering light of the dragonfly ocellus

The ERG of the dragonfly ocellus has been analyzed into four components, two of which originate in the photoreceptor cells, two in the ocellar nerve fibers (Ruck, 1961 a). Component 1 is a sensory generator potential, component 2 a response of the receptor axons. Component 3 is an inhibitory postsynaptic potential, component 4, a discharge of afferent nerve impulses in ocellar nerve fibers. Responses to flickering light are examined in terms of this analytic scheme. It has been found that the generator potential can respond to higher rates of flicker—up to 220/sec.—than can the receptor axon responses, the postsynaptic potential, or the ocellar nerve impulses. The maximum flicker fusion frequency as measured by fusion of the ERG is that of the sensory generator potential itself.