Abstract
Dorsal ocelli are small cup-like organs containing a layer of photoreceptor cells, the short axons of which synapse at the base of the cup with dendritic terminals of ocellar nerve fibers. The ocellar ERG of dragonflies, recorded from the surface of the receptor cell layer and from the long lateral ocellar nerve, contains four components. Component 1 is a depolarizing sensory generator potential which originates in the distal ends of the receptor cells and evokes component 2. Component 2 is believed to be a depolarizing response of the receptor axons. It evokes a hyperpolarizing postsynaptic potential, component 3, which originates in the dendritic terminals of the ocellar nerve fibers. Ocellar nerve fibers in dragonflies are spontaneously active, discharging afferent nerve impulses (component 4) in the dark-adapted state. Component 3 inhibits this discharge. The ERG of the cockroach ocellus is similar. The main differences are that component 3 is not as conspicuous as in the dragonflies and that in most cases ocellar nerve impulses appear only as a brief burst at "off." In one preparation a spontaneous discharge of nerve impulses was observed. As in the dragonflies, this was inhibited by illumination.
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Selected References
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- BURTT E. T., CATTON W. T. Electrical responses to visual stimulation in the optic lobes of the locust and certain other insects. J Physiol. 1956 Jul 27;133(1):68–88. doi: 10.1113/jphysiol.1956.sp005567. [DOI] [PMC free article] [PubMed] [Google Scholar]
- FUORTES M. G. Electric activity of cells in the eye of Limulus. Am J Ophthalmol. 1958 Nov;46(5 Pt 2):210–223. doi: 10.1016/0002-9394(58)90800-6. [DOI] [PubMed] [Google Scholar]
- GOLDSMITH T. H., RUCK P. R. The spectral sensitivities of the dorsal ocelli of cockroaches and honeybees; an electrophysiological study. J Gen Physiol. 1958 Jul 20;41(6):1171–1185. doi: 10.1085/jgp.41.6.1171. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HARTLINE H. K., WAGNER H. G., MACNICHOL E. F., Jr The peripheral origin of nervous activity in the visual system. Cold Spring Harb Symp Quant Biol. 1952;17:125–141. doi: 10.1101/sqb.1952.017.01.013. [DOI] [PubMed] [Google Scholar]
- RUCK P. Electrophysiology of the insect dorsal ocellus. II. Mechanisms of generation and inhibition of impulses in the ocellar nerve of dragonflies. J Gen Physiol. 1961 Jan;44:629–639. doi: 10.1085/jgp.44.3.629. [DOI] [PMC free article] [PubMed] [Google Scholar]
- TOMITA T. The nature of action potentials in the lateral eye of the horseshoe crab as revealed by simultaneous intra- and extracellular recording. Jpn J Physiol. 1956 Dec 31;6(4):327–340. doi: 10.2170/jjphysiol.6.327. [DOI] [PubMed] [Google Scholar]