Electroretinograms from Crayfish Compound Eyes Evokedby Mid-infrared Irradiation:Spectral Sensitivity Measurements of the Fast and Late Reactions

Abstract

Free-electron lasers at Kyoto University and Nihon University were used as mid-infrared (IR) irradiation stimuli for crayfish compound eyes, and two corneal reactions were detected as the amplitude function of electroretinograms and were identified as a fast reaction and a late reaction. This fast reaction is a new discovery. The spectralsensitivities of the two corneal reactions were measured with an electrophysiological technique at eight selectedmid-IR wavelengths in 2 µm steps ranging from 4 to 18 µm. The wavelength at which maximum sensitivity wasreached was 12–14 µm for the fast reaction and 10–12 µm for the late reaction. In addition, adaptation (attenuationand restoration) of the late reaction to repeated mid-IR stimuli was observed.