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Biomedical subjects

E Dodt

Publications and source records attributed to E Dodt.

36 records · Page 2Linked to original sources
PubMed1975

Early receptor potential from the pineal photoreceptor.

Rapid photoresponses were obtained from the pineal organ of Rana catesbeiana and Rana esculenta comparable to the early receptor potential (ERP) of the retina of their lateral eyes. Light source was a xenon filled discharge tube with a maximum energy input of 365 J. The flash duration was 600 mu sec measured at 1/3 peak amplitude. The response pattern of the ERP of the exposed Epiphysis cerbri (intracranial portion of the frog's pineal organ) resembled the ERP of the isolated retina and the R1 deflection of the ERP of the eye-cup. It was greatly diminished during consecutive flashes and was absent during light adaptation. It was confined to the Epiphysis cerbri and was similar in time course and shap to, though smaller as, the ERP of the isolated retina. The photoresistant component of the ERP in the eye-cup was lacking in the Epiphysis cerbri and in the isolated retina. The action spectrum of the ERP of the Epiphysis cerbri closely resembled the photopigment absorption of rhodopsin indicating that the structural cones of the pineal organ contain a photopigment different from the retinal cones of the frog's lateral eye.

Action Potentials↗
PubMedDate not supplied

Effect of pre-adaptation on pattern electroretinogram (P-ERG).

Up to now light and dark adaptation are considered as of minor importance when recording the pattern electroretionogram (P-ERG) which in man reflects cone vision. In order to test this supposition transient P-ERGs were recorded in six healthy subjects to a reversing checkerboard pattern produced by a pivoted mirror system after two minutes of pre-exposure to darkness (1), to the pattern reversal stimulus (2), and to uniform illumination of 3.3 log cd/m2 (3). Field size was 18 x 20 degrees, check size 69 min of arc, reversal frequency 3.5/s, contrast 0.95. When recording the P-ERG within the first 30 s after pre-exposure, the amplitude/luminance function of the p-q and the q-r component was shifted along the luminance axis without changing the maximum amplitude. For a criterion response of 1.5 microV there was a sensitivity difference of 1.3 log units between measurements after pre-exposure to darkness and after strong illumination. Furthermore, the P-ERG latencies of the q and the r component displayed significantly shorter values after pre-exposure to strong light than after darkness, whereas no change of p-latency was recorded. We conclude that pre-exposure to darkness and strong illumination has no effect on the P-ERG elicited at high luminance levels. However, pre-adaptation should be considered when recording the P-ERG at luminance levels near threshold.

Adaptation, Physiological↗