Abstract
Visually evoked cortical potentials (VECP) were elicited by test fields between 5° and 110° in diameter under scotopic and photopic conditions. Photopic and scotopic responses in the VECP were identified by implicit time measurements (70–200 ms for the photopic, 180–400 ms for the scotopic response).
The slope of the implicit time vs. luminance curves was steeper under scotopic than under photopic conditions. The change of slope was identified by the spectral luminosity functions as the transition from rod to cone activity.
With a test stimulus of 30 times absolute threshold the scotopic response was obtained not before 10 minutes in darkness. The maximum height of response was reached after 35 minutes of dark adaptation.
Spatial summation of the scotopic response was seen for test flashes between 5° and 110° in diameter (central fixation).
Moving a test field of 5° in the visual field, the sensitivity of the scotopic response (based on the implicit time) increased from the center towards the nasal periphery with a maximum at about 20°. Further move to 40° eccentricity decreased the scotopic sensitivity gradually. The photopic sensitivity decreased strongly as the stimulus field moved from center to nasal periphery.
Sensitivity measurements based on an implicit time criterion of the VECP closely agree with the known distribution of rod and cone cells and the sensory threshold measurements of the scotopic and photopic system.
Due to the magnification properties of the visual cortex, the visually evoked cortical potential (VECP) in man reflects mainly the activity of the foveal and parafoveal parts of the retina (Potts et al., 1965; De Voe et al., 1968). However, under appropriate conditions of stimulation it has been possible to record cortical signals of scotopic origin, predominantly in VECP components marked by long implicit time (van Balen & Henkes, 1960).
Vaughan (1964) identified the break in the implicit time vs. intensity plots as the transition of rod to cone VECP. Using the scotopic VECP as a clinical test of peripheral retinal function, Adams et al. (1969) found abnormal responses in patients with night blindness, while the photopic VECP was normal; the reverse was seen in patients suffering from macular degeneration. In 16 patients with hemianopsia Kojima et al. (1972) observed asymmetries between the responses from the two hemispheres by means of the scotopic VECP. Using an implicit time criterion Huber & Adachi-Usami (1972) found the spectral sensitivity of the scotopic VECP to agree well with the scotopic CIE luminosity function.
The present study was conducted to investigate the spatial distribution of retinal sensitivity by means of scotopic and photopic VECP. Moreover, spatial summation of the scotopic response was determined for test flashes up to 110° in diameter.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Adachi-Usami, E. & E.-J. Kellermann: Spatial summation of retinal excitation as obtained by the scotopic VECP and sensory threshold. Ophthal. Res. 5, 308–316 (1973).
Adams, W. L., G. B. Arden & J. Behrman: Responses of human visual cortex following excitation of peripheral rods. Brit. J. Ophthal. 53, 439–452 (1969).
Baien, A. T. M., Van & H. E. Henkes: Recording of the occipital lobe response in man after light stimulation. Brit. J. Ophthal. 44, 449–460 (1960).
CIE: International Lighting Vocabulary, 3rd Edition, Paris 1970, Publication No. 17.
De Mott, D. W. & R. M. Boynton: Retinal distribution of entopic stray light. J. opt. Soc. Am. 48, 13–22 (1958).
De Voe, R. G., H. Ripps & H. G. Vaughan, Jr.: Cortical responses to stimulation of the human fovea. Vision Res. 8, 135–147 (1968).
Dodt, E. & E. Alexandridis: Electroretinography and pupillography as supplementary tools in the evaluation of retinal function in man. 6th ISCERG Symp. Erfurt 1967; VEB Georg Thieme, Leipzig 1968, pp. 459–466.
Gastaut, H. & H. Régis: Visually evoked potentials recorded transcranically in man. In: L. D. Proctor & W. R. Adey (eds.): The Analysis of Central Nervous System and Cardiovascular Data using Computer Methods (1964 Symposium), Washington, NASA 1965, pp. 7–34.
Holmes, G.: Disturbances of vision by cerebral lesions. Brit. J. Ophthal. 2, 253–384 (1918).
Huber, C. & E. Adachi-Usami: Scotopic visibility curve in man obtained by the VER. In: G. B. Arden (ed.) The Visual System: Neurophysiology, Biophysics, and Their Clinical Application. Proc. 9th ISCERG Symp. Brighton 1971, Adv. exp. med. Biol. 24, 189-198, Academic Press New York 1972.
Kojima, M., H. Abe & K. Iwata: The VER in patients with hemianopsia. Folia Ophthal. Jap. 23, 962–968 (1972).
Le Grand, Y.: Recherches sur la diffusion de la lumière dans l’oeil humain. Rev. Opt. 16, 241 (1937).
Lith, G. H. M., Van: Simultane Bestimmung der elektroretinographischen und sensorischen Reizschwelle. Vision Res. 6, 185–197 (1966).
Lith, G. H. M., Van & E. Henkes: The local electric response of the central retinal area. 6th ISCERG Symp. Erfurt 1967, VEB Georg Thieme, Leipzig 1968, pp. 163-170.
Østerberg, G.: Topography of the layer of rods and cones in the human retina. Acta Opthal. Kbh. Suppl. 6, 1–102 (1935).
Potts, A. M. & E. H. C. Marriot: Studies on the visual evoked response. I. The use of a 0.06 degree red target for evaluation of foveal function. Invest. Ophthal. 4, 303–309 (1965).
Sloan, L. L.: Rate of dark adaptation and regional threshold gradient of the dark adapted eye. Pnysiologic and Clinical Studies. Am. J. Ophthal. 30, 705–720 (1947).
Stiles, W. S. & B. H. Crawford: The effect of a glaring light source on extrafoveal vision. Proc. Roy. Soc (London) 122B, 255 (1937).
Vaughan, H. G., Jr.: The perceptual and physiologic significance of visual evoked responses recorded from the scalp in man. In: Burian and Jacobson (eds.) Clinical Electroretinography. Vision Res. Suppl. 203-223 (1964).
Wald, G.: Human vision and the spectrum. Science 101, 653–658 (1945).
Wooten, B. R.: Photopic and scotopic contribution to the human visually evoked cortical potential. Vision Res. 12, 1647–1660 (1972).
Author information
Authors and Affiliations
Editor information
Rights and permissions
Copyright information
© 1977 Dr W. Junk b.v. Publishers
About this chapter
Cite this chapter
Kojima, M., Zrenner, E. (1977). Local and Spatial Distribution of Photopic and Scotopic Responses in the Visual Field as Reflected in the Visually Evoked Cortical Potential (VECP). In: Lawwill, T. (eds) ERG, VER and Psychophysics. Documenta Ophthalmologica, vol 13. Springer, Dordrecht. https://doi.org/10.1007/978-94-010-1312-3_5
Download citation
DOI: https://doi.org/10.1007/978-94-010-1312-3_5
Publisher Name: Springer, Dordrecht
Print ISBN: 978-94-010-1314-7
Online ISBN: 978-94-010-1312-3
eBook Packages: Springer Book Archive