EMPIRIC LIMITS OF ROD PHOTOCURRENT COMPONENT UNDERLYING A-WAVE RESPONSE IN THE ELECTRORETINOGRAM

被引:29
作者
BRETON, ME
MONTZKA, DP
机构
[1] The Scheie Eye Institute, Department of Ophthalmology, University of Pennsylvania School of Medicine, Philadelphia, 19104, PA
关键词
A-WAVE; B-WAVE; ELECTRORETINOGRAM; PHOTOCURRENT;
D O I
10.1007/BF00160948
中图分类号
R77 [眼科学];
学科分类号
100212 ;
摘要
The corneally recorded rod photocurrent component (photoresponse) underlying the a-wave feature of the electroretinogram was analyzed. The results set empiric limits on critical photoresponse variables. Measurements were obtained from four normal adult subjects on a-wave amplitude, a-wave velocity, b-wave amplitude, b-wave implicit time and b-wave height above baseline. At high intensity, interference from the b-wave component was minimized and the amplitude of the saturated photoresponse component was approximated by the a-wave feature. At lower intensities, the a-wave feature represented progressively less of the underlying photoresponse amplitude. Photoresponse amplitude saturation was signaled by the abrupt slowing of the rate of decline of b-wave peak latency and occurred at an intensity about 2.5 log units above the first appearance of the b-wave. At the intensity of photoresponse saturation, the peak amplitude of the a-wave feature was only about 25% of the maximum amplitude of the underlying photoresponse component. A-wave leading edge velocity was found to increase up to 3 log units above the intensity of photoresponse amplitude saturation and to provide a good estimate of photoresponse velocity at higher intensities. A cascaded low-pass filter model with modifications to accommodate amplitude and timing nonlinearities was used to generate a set of probable underlying photoresponses from the analysis of a-wave amplitude and velocity. Movement of the a-wave leading edge to the left at higher intensities in algebraic combination with a static b-wave leading edge above the intensity of photoresponse amplitude saturation was found to explain the second rise of the b-wave amplitude function and the decline of b-wave amplitude above baseline at high intensities. This analysis provides a basis for modeling the underlying photoresponse on a biochemical level and for interpreting photoreceptor damage in disease states.
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收藏
页码:337 / 361
页数:25
相关论文
共 29 条
[1]  
ARDEN GB, 1976, EYE, pCH7
[2]   THE PHOTOCURRENT, NOISE AND SPECTRAL SENSITIVITY OF RODS OF THE MONKEY MACACA-FASCICULARIS [J].
BAYLOR, DA ;
NUNN, BJ ;
SCHNAPF, JL .
JOURNAL OF PHYSIOLOGY-LONDON, 1984, 357 (DEC) :575-607
[3]  
BAYLOR DA, 1979, J PHYSIOL-LONDON, V288, P589
[4]  
BIRCH DG, 1987, INVEST OPHTH VIS SCI, V28, P140
[5]  
BRESNICK GH, 1987, ARCH OPHTHALMOL-CHIC, V105, P660
[6]  
BRETON ME, 1991, OPHTHALMOLOGY, V98, P1837
[7]  
BRETON ME, 1989, OPHTHALMOLOGY, V96, P1343
[8]   ORIGIN OF EARLY RECEPTOR POTENTIAL OF RETINA [J].
BRINDLEY, GS ;
GARDNERM.AR .
JOURNAL OF PHYSIOLOGY-LONDON, 1966, 182 (01) :185-&
[9]   NEW RECEPTOR POTENTIAL OF MONKEY RETINA WITH NO DETECTABLE LATENCY [J].
BROWN, KT ;
MURAKAMI, M .
NATURE, 1964, 201 (491) :626-&
[10]   KINETICS AND COMPONENTS OF THE FLASH PHOTOCURRENT OF ISOLATED RETINAL RODS OF THE LARVAL SALAMANDER, AMBYSTOMA-TIGRINUM [J].
COBBS, WH ;
PUGH, EN .
JOURNAL OF PHYSIOLOGY-LONDON, 1987, 394 :529-572