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1.
目的 :采用黄色背景光蓝闪光刺激ERG(blue on yellowflash ,ERG)方法 ,探讨非渗出性年龄相关性黄斑变性(AMD)的短波长敏感视锥细胞通路、视杆细胞系统以及双谷a波的改变特征。方法 :采用AVES 80 0 0型视觉电生理检查系统 ,在Ganzfeld刺激器上设置黄色背景光 (5 70nm)和蓝色刺激光 (45 0nm) ,检查程序及参数参照ISCEV标准。对正常人 (40眼 )和非渗出性AMD(40眼 )进行观察 ,记录视杆细胞反应、最大反应和视锥细胞反应。结果 :与对照组比较 ,非渗出性AMD的双谷a波数减少 ,视杆细胞反应b波振幅降低(P <0 .0 1) ,最大反应b/a比值异常 (P <0 .0 5 )。视锥细胞反应b波振幅下降 (P <0 .0 0 1) ,长波长敏感视锥细胞 (L cone)和中波长敏感视锥细胞 (M cone)活动受到明显压抑 ,短波长敏感视锥细胞 (S cone)活动得到充分反映。结论 :黄色背景光蓝闪光刺激ERG可以对视杆细胞系统和短波长敏感视锥细胞通路进行检测 ,非渗出性AMD的短波长敏感视锥细胞通路、视杆细胞系统和b/a比值异常 ,双谷a波数减少。黄色背景光蓝闪光刺激ERG具有临床应用价值  相似文献   

2.
The human S-cone ERG and single neuron responses from cells mediating the signals of short wavelength sensitive cones (S-cones) were examined and compared with the responses of long (L) and middle (M) wavelength sensitive cones. The S-cone system contributes a relatively small signal to the total cone ERG; it can be selectively light adapted; its b-wave is slower than that of L- and M-cone b-wave; and it lacks a d-wave. Transient tritanopia, a striking feature of S-cone on-retinal ganglion cells, is relatively weak at the level of the ERG. The responses of geniculate neurons were studied using a slowly moving border of energy and wavelength contrast. The ability of cells to respond to wavelength contrast across a border in which energy contrast was reversed was tested in all major varieties of retino-geniculate neurons in the macaque monkey. Cells mediating the signals of S-cones are unique in responding to wavelength rather than energy contrast. The most effective stimulus for such cells is white/yellow wavelength contrast at minimum energy contrast. It is suggested that the S-cone system's major role is to detect wavelength (chromatic) contrast and in particular white and grey from yellow and brown at minimal energy (brightness) contrast.  相似文献   

3.
To investigate the contributions of amacrine cells to red-green opponency, a linear computational model of the central macaque retina was developed based on a published cone mosaic. In the model, amacrine cells of ON and OFF types received input from all neighboring midget bipolar cells of the same polarity, but OFF amacrine cells had a bias toward bipolar cells whose center responses were mediated by middle wavelength sensitive cones. This bias might arise due to activity dependent plasticity because there are midget bipolar cells driven by short wavelength sensitive cones in the OFF pathway. The model midget ganglion cells received inputs from neighboring amacrine cells of both types. As in physiological experiments, the model ganglion cells showed spatially opponent responses to achromatic stimuli, but they responded to cone isolating stimuli as though center and surround were each driven by a single cone type. Without amacrine cell input, long and middle wavelength sensitive cones contributed to both the centers and surrounds of model ganglion cell receptive fields. According to the model, the summed amacrine cell input was red-green opponent even though inputs to individual amacrine cells were unselective. A key prediction is that GABA and glycine depolarize two of the four types of central midget ganglion cells; this may reflect lower levels of the potassium chloride co-transporter in their dendrites.  相似文献   

4.
de Monasterio and Gouras (1977) have shown that the short-wave lobe of tri-phasic, red-green opponent ganglion cells in rhesus and cynomologus monkeys results from interaction between middle- and long-wave sensitive cones. They have argued that the same is true for the human red-green system. We show that the short-wave red lobe of the human red-green system as determined by hue cancellation must result from the interaction of all three cone types with the short-wave receptor predominating.  相似文献   

5.
PURPOSE: To determine the visual pigment content of the rods and cones of the guinea pig (Cavia porcellus) and to quantify the level of coexpression of pigments within individual cones. METHODS: Microspectrophotometry was used to measure the absorbance spectrum of visual pigments in individual rods and cones from three retinal regions: dorsal, ventral, and a subequatorial transition zone. Partial bleaching was used to establish whether two spectrally distinct visual pigments were present within a single cone. RESULTS: Rods possessed a pigment with a wavelength of maximum absorbance (lambda(max)) close to 500 nm. A population of middle-wave-sensitive cones (M cones) contained a pigment with lambda(max) at approximately 530 nm, and a short-wave-sensitive cone population (S cones) contained a pigment with lambda(max) close to 400 nm. The majority of cones in all regions were M cones. Approximately 10% of cones in the transition region were found to coexpress the M and S cone pigments in a ratio of approximately 4:1. Coexpression was not detected in S cones. CONCLUSIONS: In C. porcellus, coexpression of cone pigments occurs in a small number of cells but is biased in favor of the M pigment. Given the relatively low level of coexpression, detectable in only approximately 10% of the cones in the transition region, it is unlikely to cause any significant detriment to dichromatic color vision.  相似文献   

6.
In man the electroretinogram to pattern reversal stimuli (P-ERG) represents a cone response of the proximal retina, dominated by the cone mechanisms sensitive to red (R) and green (G). Additionally there is a cone mechanism sensitive to blue (B) which can be studied with and without steady exposure to yellow light. During exposure to a super-imposed uniform yellow background (576 nm) the transient P-ERG of the B cones is represented by potentials of small amplitude (< 1 V). The latency (peak time) of the response is about 30 ms longer than that of the midspectral (R and G) cones. Furthermore, the P-ERG of the B cones saturates at low luminances and exhibits a maximum amplitude at about 460 nm. Without yellow adaptation, the P-ERG of the B cones can be studied only with low-intensity stimuli of short wavelengths. Near threshold, both the long-latency response of the B cones and the short-latency response of the R and G cones are recorded simultaneously, forming a double-peaked wave shape. At suprathreshold luminances, even of short wavelength (435 nm) the P-ERG of the B cones is concealed by the larger short latency response of the midspectral cone mechanism.  相似文献   

7.
W Verdon  P A Howarth 《Vision research》1988,28(10):1119-1128
Using i.r. pupillometry, we measured the response of the pupil to tritanopic metamers alternating at 0.94 Hz. These are lights that differentially stimulate only the short wavelength (S) sensitive cones. We find a response at the alternation frequency for 5 of 7 observers. This shows, for the 5 observers, that S cone signals can influence pupil size, probably via the traditional retinotectal light reflex pathway. Changing the radiance of just one of the alternating pair of lights causes the two lights to differ in their total M + L cone stimulation. The pupil's response to this imbalance can antagonize its response to S cone stimulation. By this procedure we find that imbalances in M + L cone stimulation of less than 0.3 log10 unit offset the pupil's response to S cone stimulation of more than 0.8 log10 unit. This suggests that afferent pupillary signals from S cones are weak relative to those from M + L cones.  相似文献   

8.
Ekesten B  Gouras P  Yamamoto S 《Vision research》2000,40(19):2573-2577
Responses of single retinal ganglion cells in different areas of mouse retina were studied to determine their cone inputs, using spectral sensitivity functions and chromatic adaptation. Spectral sensitivity curves were based on threshold response criteria to full field stimulation. The retina of the mouse was viewed through a dilated pupil with a surgical microscope. Ganglion cells were classified into three groups: one receiving inputs from short wave sensitive cones, a second receiving inputs from only middle wavelength sensitive cones and a third receiving inputs from both of these types of cones. The ventral retina, contained a large fraction of the first group of ganglion cells. The dorsal retina and the border between these two areas contained relatively more of the latter two groups. A small fraction of cells were found which displayed antagonistic-like interactions between photoreceptor systems. The results demonstrate that single ganglion cells in mouse retina can select responses from only one of the two cone mechanisms present in this retina, even in areas containing both types of cones.  相似文献   

9.
Thresholds were measured for a tiny, brief, violet flash on a long wavelength, B cone-isolating background in foveal locations spaced only 4 or 5′ of arc apart. Large spatial variations in B cone sensitivity were found just beyond the foveal tritanopic area even though thresholds for the same wavelength test flash hardly varied at all across these same retinal locations when the flash was detected by G cones. The relative constancy of G cone threshold suggests that these spatial variations are intrinsic to the blue-sensitive mechanism and cannot be explained by prereceptoral filtering. The spatial variations in B cone sensitivity are consistent with physiological evidence that B cones are scarce in the retina. In one observer, it was possible to discern discrete peaks in sensitivity spaced roughly 10′ of arc apart. A model is described which takes optical spread and eye movements into account to show that these peaks may represent individual B cones (or clumps of B cones).  相似文献   

10.
We measured functional input from short-wavelength selective (S) cones to neurons in the dorsal lateral geniculate nucleus (LGN) and striate cortex (area V1) in anaesthetized marmosets. We found that most magnocellular (MC) and parvocellular (PC) cells receive very little (<5%) functional input from S cones, whereas blue-on cells of the koniocellular (KC) pathway receive dominant input from S cones. Cells dominated by S cone input were not encountered in V1, but V1 cells received more S cone input than PC or MC cells. This suggests that S cone inputs are distributed broadly among neurons in V1. No differences in strength of S cone inputs were seen on comparing dichromatic and trichromatic marmosets, suggesting that the addition of a medium-long wavelength selective cone-opponent (“red-green”) channel to a dichromatic visual system does not detectably affect the chromatic properties of the S cone pathways.  相似文献   

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