Non-Invasive Recording of the Electroretinogram from Both Compound Eyes in the Cockroach Periplaneta Americana L. in Response to Light Stimuli.

This paper presents an original method for noninvasive recording of electroretinogram from both compound eyes of insects. The method was found to be highly reliable and reproducible. The photovoltaic effect, which distorts response amplitude and shape, was eliminated by using a gold recording electrode. The data obtained using this method showed that the magnitudes of the responses of the eyes in pearl mutant cockroaches, which lack screening pigment, to light stimuli were approximately four times greater than those of wild-type insects. The time to peak response decreased with increases in stimulus light intensity for shortwave and long-wave stimuli. Pearl cockroaches reached maximum responses faster than wild-type cockroaches. Results of covariance analysis indicated that these differences could not be explained completely in terms of an increase in the number of photons reaching photoreceptor membranes. This suggests that there are additional differences in the physiology of the compound eye between mutant and wild-type individuals. The positive deflection of the potential after the end of light stimulation depended on light intensity and was a reflection of receptor cell hyperpolarization. [ABSTRACT FROM AUTHOR]