1972;12:16691684. (A) Cone a-waves that were elicited in the light-adapted state using long-wavelength light stimuli of different intensities. skate, rats) while in others the cone system is the dominant one (e.g. 1903;29:388416. 1984;357:575607. The range of bright flash dark-adapted ERG a-wave of 10 normal subjects is given by the thick continuous traces. The exact cellular origin of OPs is not yet known for certain. This document, from the International Society for Clinical Electrophysiology of Vision (ISCEV), presents an updated and revised ISCEV Standard for clinical ERG testing. [PubMed], Fig. Figure 3b shows an equivalent electrical circuit of the eye (Rodieck, 1973). Jpn J Ophthalmol. The mouse electroretinogram (ERG) consists of a complex set of signals or " waves " generated by multiple types of retinal cell. Vision Res. M-wave of proximal retina in cat. Scotopic stimulus/response relations of the b-wave of the electroretinogram. J Gen Physiol.1985;86:189213. 7.5 Paired-flash analysis of the rod response: A test flash of fixed intensity induces a rod response that reflects the degree to which the dark current is reduced, and the time course of closure, followed by opening, of the cGMP-gated channels. The potential changes that were recorded from these cells in response to light stimuli were identical in shape and temporal properties to the ERG c-wave (Steinberg et al., 1970). [PubMed], Cideciyan AV, Jacobson SG. of the amplitude and time-to-peak of the a-wave and the b-wave. Thus OP recordings have sometimes been used as an indicator of background diabetic retinopathy (Larsen et al., 1980; Simonsen, 1980; Bresnick and Palta, 1987; Asi and Perlman, 1992). This lead to a push-pull model of these cell types (Sieving et al., 1994). Aetna considers ERG experimental and investigational for all other indications including the following (not an all-inclusive list): The passive electrical properties of the frogs retina, choroid and sclera for radial fields and currents. Sensitivity to light. J Neurophysiol.1970;33:323341. In: Osborne N, Chader G, editors. J Neurophysiol. 1978;18:793800.[PubMed]. The relationship to the diameter of the stimulating light is similar. Cold Spring Harb Symp Quant Biol. 21. In fact, any procedure that blocks synaptic transmission from the photoreceptors, like superfusion with cobalt ions or with high magnesium low calcium solutions, will eliminate the ERG b-wave (Furakawa and Hanawa, 1955; Sillman et al., 1969a; Pepperberg and Masland, 1978). The responsiveness of the cone system and its ability to follow fast flickering stimuli depend upon the level of ambient illumination as shown in figure 20 (Peachey et al., 1992). This phenomenon led early studies of patients with congenital stationary night blindness (CSNB) or with melanoma associated retinopathy (MAR) to conclude that the cone system was functioning normally and only the rod system was affected. The d-wave is used only when the cone ON- and OFF-channels need to be separated to identify defects specific to ON-channels (Miyake et al., 1987; Alexander et al., 1992). 2001;18:187196. Pergamon Press; 1985. p. 181219. The first one involves the rod bipolar cells. Role of K+in generation of b-wave of electroretinogram. Correlation of light-induced changes in retinal extracellular potassium concentration with c-wave of the electroretinogram. Generation of b-wave currents in the skate retina. Vol 1: Sensory processes and perception. ERGs recording from the skate. The drugs were injected into the vitreous of the rabbit eye. Therefore, the former is a slow potential at stimulus onset recorded in the dark-adapted retina, while the latter contains ON and OFF components and is recorded in light-adapted conditions (compare Figs. Reconstructing the P-II component of the human ERG response. We assume that a light stimulus elicits extracellular electrical currents that flow from sources to sinks. The b-wave is also found to be affected by drugs that modulate GABAC-type receptors indicating that negative feedback from amacrine cells onto bipolar cells can shape the photoresponses of the bipolar cells and thus, the amplitude and kinetics of the ERG b-wave (Dong and Hare, 2002). An evaluation of retinal electrical anisotropy. Patients' eyes are stimulated with light and the resulting electrical activity from their retinal cells is measured by skin or corneal electrodes. Based on these observations, Miller and Dowling (1970) suggested that depolarization of the Mller cell membrane in the distal retina resulted in extracellular currents that were expressed as the b-wave. 1977;267:737766. 1979;48:163222. 1999;16:727741. His dark-adapted a-wave is smaller in amplitude than that of the normal range and when scaled up exhibits considerably slower kinetics. The paired-flash technique has been developed to reconstruct the P-III component (Pepperberg et al., 1997; Hetling and Pepperberg, 1999). Vision Res. Under regular recording conditions of the ophthalmic clinic, it can be accepted that rod-mediated electrical signals can follow flickering stimuli up to 15Hz. Multifocal electroretinogram revealed moderately and mildly decreased response in the macula and paramacula, respectively (Figure 1C and D). These and other studies reported a light-induced increase in extracellular potassium in the outer and inner plexiform layers. 3a. Invest Ophthalmol. Figure 29C illustrates the construction of the rod response underlying the test flash. This change will be reflected in the ERG responses that are measured with extra-ocular electrodes. The origins of these waves are reviewed briefly for the C57BL/6J . A Flash ERG (FERG) is a test which measures the electrical response of the eye's light-sensitive cells (rods and cones). The ERG originates from extracellular currents that are generated in response to a light stimulus. J Neurophysiol. (A) The effects of a mixture of bicuculline + strychnine on the ERG response of one rabbit (trace 2). 1985;25:13651373. It has been argued, based on recent findings on the rod system in mammals and primates, that rod signals can be transmitted via two pathways. Comparison of the waveforms of the ON bipolar neuron and the b-wave of the electroretinogram. The mouse electroretinogram (ERG) consists of a complex set of signals or "waves" generated by multiple types of retinal cell. Since the neural retina is supplied by the retinal vasculature and the photoreceptors by the choroidal plexus, this experimental manipulation, or pathological cases, effectively eliminates light-induced electrical activity in the neural retina from the photoreceptors. Am J Ophthalmol. 1968;7:214218. The reduction of [K+]o in the photoreceptor layer and the increase in the outer and inner plexiform layers are clearly seen. I. Doc Ophthalmol. [2] The PERG assesses both macular and retinal ganglion cell . Amplification and kinetics of the activation steps in phototransduction. As the stimulus intensity is increased, the ERG b-wave increases in amplitude and becomes faster in kinetics. Fig. Vis Neurosci. Furthermore, the temporal properties of P-II are of value to the clinician. 1969, Finkelstein D, Gouras P, Hoff M. Human electroretinogram near the absolute threshold of vision. Vision Res. Acta Ophthalmol (Copenh). 26. 1951;168:738. Current source-density analysis. 1D) are elicited by fast bright flashes (50 or 100ms in duration) and therefore, only the a-wave and b-wave are seen. Progress in retinal research. II. Therefore, the reduction in the extracellular concentration of potassium ions in the photoreceptor layer, due to light absorption in the photoreceptors, elicits changes in the trans-membrane potential of the Mller cells and is expressed as the slow P-III component of the ERG. As can be seen in these ERG records, the a-wave saturates for the 2 brightest light stimuli. The contribution of voltage- and time-dependent poassium conductances to the electroretinogram in rabbits. According to Ohms law, the potential difference between two points is independent of the pathway through which the current is flowing. The size of the pupil is the major determinant of light intensity to the retina. 24. The data points (red circles and blue triangles) represent data from normal subjects recorded in two different laboratories (Perlman, 1983). Assessing abnormal rod photoreceptor activity with the a-wave of the electroretinogram: applications and methods. [PubMed], Masu M, Iwakabe H, Tagawa Y, Miyoshi T, Yamashita M, Fukuda Y, Sasaki H, Hiroi K, Nakamura Y, Shigemoto R, Takada M, Nakamura K, Nakao K, Katsuki M, Nakanishi S. Specific deficit of the ON response in visual transmission by targeted disruption of the mGluR6 gene. Namely, the amplitude V is linearly related to the light intensity I with a slope of Vmax/s. Localization of origins of electroretinogram components by intra retinal recording in the intact cat eye. 3), it is possible to isolate disorders that affect the sensitivity of the rods, from disorders that affect their maximum response. J Physiol. It was proposed to represent changes in membrane potential of Mller cells due to light-induced increases in the extracellular potassium in the proximal retina (Karwoski and Proenza, 1977, 1980). 8. Vis Neurosci. [PubMed], Brown KT, Wiesel TN. Animal numbers are indicated in figure . 1985;85:911931. Unlike Einthoven and Jolly who suggested that the waves reflected transient chemical processes, Piper suggested that all the ERG components lasted for the duration of the light stimulus. Light-induced potassium fluxes in the skate retina. [PubMed], Brown KT, Murakami M. A new receptor potential of the monkey retina with no detectable latency. Such an experiment is illustrated in figure 29. The b-wave is also affected by OFF-center bipolar cells and by light-induced activity in 3rd order retinal neurons (amacrine and ganglion cells). The vertical dashed lines represent the time frame used to derive the theoretical rod P-III component. Under certain conditions barium ions even caused augmentation of the b-wave as shown in figure 8 (Lei and Perlman, 1999). Vis Neurosci. He showed that light illumination through the pupil, which had previously been covered, caused a slight movement of a galvanometer, suggestive of a positive electrical change in the cornea relative to the back of the eye (Armington, 1974). Adding barium ions to block potassium conductance of the Mller cells does not completely eliminate the M-wave. 1968;8:697700. [PubMed], Doslak MJ, Plonsey R, Thomas CW. These wavelets are much faster than the complex of the a- and b-waves. Fig. 1988;68:293304. J Neurophysiol. The difference between these field potentials arises from their photoreceptor basis. According to Ohms law in electricity, when an electrical current flows through a resistor, a gradient of electrical potential is formed that equals the product of multiplying the magnitude of the current by that of the resistance. Wave III was equivalent to the c-wave. [PubMed], Hood DC, Birch DG. Depth recordings reveal that the OPs attain maximum amplitude when the microelectrode is in the inner retina (Brown, 1968). (C) Reconstruction of the rod response underlying the ERG response to the test flash (continuous trace). A model, similar to that suggested for the rod P-III, has also been suggested for the cone P-III (Hood and Birch, 1993, 1995). [PubMed], Karowski CJ, Proenza LM. Handbook of perception and human performance. (B) The responses in A were corrected for cone contribution. However, the b-wave ratio is normal indicating normal signal transmission. The full field electroretinogram (ERG) is used to detect loss of retinal function or distinguish between retinal and optic nerve lesions. Furthermore, the amplitude-stimulus intensity relationship was similar for the Mller cell photoresponses and the ERG b-wave. The a-wave is used as the independent variable and is used together with the normal b-wave to a-wave ratio (of Fig. The differences in the properties of these waves are described for 34 strains of mice and 11 F1 hybrid mice, as is the way that inter-strain . [PubMed], Bresnick GH, Palta M. Oscillatory potential amplitude. 1970b;9:5863. The thick continuous traces show the range of a-waves that were recorded from 10 volunteers with normal vision in the dark-adapted state using a white light stimulus of 664 cd-s/m2. The full-field electroretinogram (ERG) is a mass electrophysiological response to diffuse flashes of light and is used widely to assess generalized retinal function. Fig. However, the time-to-peak of the ERG b-wave is not the time-to peak of the isolated P-II component but rather depends upon the summation of P-II and P-III (Hood and Birch, 1992). [PubMed], Perlman I. Both systems operate independently with very little interactions between them. New York: Academic Press. The responses are of larger amplitude and are characterized by faster rise times as the irradiance of the adapting field is raised. What does it do? Vision Res. In figure 24, the mean (+/- s.d) of the b-wave ratios for 20 volunteers with normal vision is plotted as a function of the a-wave amplitude. As stimulus intensity is increased, the b-wave increases in amplitude until a plateau is reached at intensities brighter by about 2 log units than that needed to elicit the smallest recordable b-wave. Current source density analysis of the electroretinographic d-wave of frog retina. Proc Natl Acad Sci U S A. Faber DS. & Brown, K. T. (1965). 19. The b-wave is also eliminated when the blood flow through the central retinal artery is blocked either intentionally in laboratory animals (Noell, 1954; Brown and Watanabe, 1962), or in human patients (Nilsson, 1971). (C) The ERG response of a rabbit to a flash (20_s) flash of white light. [PubMed], Dick E, Miller RF, Bloomfield S. Extracellular K+activity changes related to electroretinogram components. The effects of barium chloride solution injected into the vitreous of one eye, while saline was injected into the vitreous of the other eye, were tested. This component of the ERG is also referred to as the receptor component. This is the light current and basically reflects the reduction in the dark currents due to light absorption in the photoreceptor outer segments, and closure of cGMP-gated cationic channels (see chapter on photoreceptors)(Penn and Hagins, 1969; Sillman et al., 1969b). [PubMed], Dodt E. Cone electroretinography by flicker. Depth recordings of the ERP with microelectrodes and intracellular recordings led to the conclusion that the ERP originated in the photoreceptors (Brown et al., 1965; Murakami and Pak, 1970). Under special conditions of ERG recordings, the c-wave can be observed in patients. He reported that a sink for the b-wave was in the distal part of the retina, most probably in the outer plexiform layer, while the source was distributed proximally and distally to the sink. 1988;29:16151622. 1988;3:8487. Effects of some common cations on electroretinogram of the toad. 11. The exact source of the ERG b-wave is still under dispute. [PubMed], Heynen H, Wachtmeister L, van Norren D. Origin of the oscillatory potentials in the primate retina. The global or full-field electroretinogram (ERG) is a mass electrical response of the retina to photic stimulation. After 3 months without RLRL therapy, the bilateral outer retinal damage partially recovered ( Figure 2 C and D), and the visual acuity improved to 20/25 OU. Nowadays the electroretinogram response is commonly abbreviated to theERG. These authors work was the foundation for the form of analysis of the ERG used to the present day. Amplitude-intensity (A) and latency-intensity (B) for the STR and a-wave that were recorded in the dark-adapted cat. Furthermore, it was shown that carriers of X-linked retinitis pigmentosa, who had no visual defects, could be identified by their reduced ERP recordings (Berson and Goldstein, 1970b). [PubMed] [Free Full text in PMC], Pepperberg DR, Brown PK, Lurie M, Dowling JE. A Fast Fourier Transform (FFT) can be applied in order to derive the power spectrum (Fig. The electroretinogram (ERG) is an examination that evaluates the function of the eye's retinal cells. This electrical response appears immediately after stimulus onset and has a biphasic pattern as shown in figure 10. Nature. 1992;449:719758. In primates, Sieving and coauthors (1994) propose that the b-wave of the photopic ERG response are mainly contributed by the ON-center bipolar cells but are opposed by OFF-center bipolar cells. Vision Res. [PubMed], Murakami M, Kaneko A. Sub components of P3 in cold-blooded vertebrate retinae. Regardless of the exact mechanism, the b-wave is telling us about light-induced electrical activity in retinal cells post-synaptic to the photoreceptors. The data indicate that the amplitude of the b-wave is significantly increased by the mixture of bicuculline + strychnine, while TTX significantly delays the time-to-peak. 1966;210:103104. [PubMed] [Free Full text in PMC]. Nevertheless, ERG responses of turtle, bullfrog, rabbit and human (Fig. This describes the entire contribution of the photoreceptors to the ERG the P-III component (Hood and Birch, 1990, 1995). 6. 1982;31:191197. The a-wave and b-wave are followed by the slow corneal-positive c-wave. Note the different temporal properties and amplitudes of the two responses. The vertebrate retina: principles of structure and function. A dissection of the electroretinogram from the isolated rat retina with microelectrode and drugs. Therefore, any change in the magnitude of this resistor will affect the distribution of currents between the retinal pathway (IA) and the remote pathway (IB). These responses reflect mainly cone contribution and can be subtracted from the responses to white light stimuli and thus isolate the rod ERG responses. [PubMed], Reichelt W, Pannicke T. Voltage-dependent K+currents in guinea pig Mller (glial) cells show different sensitivities to blockade by Ba2+Neurosci Lett.1993;155:1518. J Physiol. A computational model of the amplitude and implicit time of the b-wave of the human ERG. Fig. [PubMed], Szikra T, Witkovsky P. Contributions of AMPA- and kainate-sensitive receptors to the photopic electroretinogram of Xenopus retina. The flash electroretinogram (ERG) represents a serial ensemble of neural responses that can be used to objectively evaluate retinal function on a layer-by-layer basis. Three different intensities of the light stimulus were applied. Furthermore, when the retina was separated from the pigment epithelium, the ERG response contained normal a- and b-wave, but the c-wave disappeared. Relation to severity of diabetic retinopathy. Area under the receiver operating characteristic (ROC) curve was used to compare effectiveness of the 4 ERG parameters (Rmax, Log K, b/a wave ratio . Exposing the vertebrate retina to 2-amino-4-phosphonobutyric acid (APB), a specific agonist of glutamate metabotropic receptors, eliminates the ERG b-wave (Gurevich and Slaughter, 1993) as shown in figure 6B. It was followed by a positive wave and a final slower wave that was also positive. 7b. Figure 6 shows ERG responses from dark-adapted rabbits that were recorded 3 hours after intravitreal injection of L-glutamate or 2-amino-phosphonobutyric acid (APB) into one eye and saline into the fellow control eye (A and B respectively). Since L-glutamate is the neurotransmitter of the photoreceptors, exposing the retina to agonists or antagonists of L-glutamate can effectively block synaptic transmission from the photoreceptors and isolate the contribution of the photoreceptors to the ERG. In a detailed study in cat and monkey, it was found that the STR could be eliminated by aspartate while the a-wave that was elicited by bright light stimuli was spared, supporting the post-receptoral origin of the STR (Wakabayashi et al., 1988). Accurate measurement of the P-II amplitude can supply valuable information to the clinician on the functional integrity of the retina. This suggestion was later supported by experiments in which barium ions, used to block the potassium conductance of Mller cells, eliminated the M-wave (Karwoski et al., 1989). Both are negative-going field potentials that reflect the effects of light-induced potassium changes upon the Mller cells in the proximal retina. They replaced the vitreous humor of cats with heavy oil in order to abolish current flow from the retina to distant sites and thereby ensured large potential recordings of local ERG from the retinal surface. 1987;31:8187. The human rod ERG: correlation with psychophysical responses in light and dark adaptation. The change in potassium alters the membrane potential of Mller cells, generating electrical currents in these two regions of the Mller cell, and exiting through its distal and proximal ends (Ripps and Witkovsky, 1985). Any disorder that is localized to the photoreceptors and does not involve more proximal sites will be expressed in abnormal a-wave amplitude but normal b-wave to a-wave ratio. 5A) indicates that the temporal properties of the KRG match closely with those of the ERG c-wave. 1990;5:379387. The relationship between amplitude and intensity of the ERG waves can be described by the following hyperbolic function (Fulton and Rushton, 1978; Hood and Birch, 1992). The importance of adding this low-pass filter to fit the phototransduction model to the cone a-wave is illustrated in figure 26. The pigment epithelium layer (R-membrane) offers the highest resistance to electrical current along the ocular tissues (Brindley, 1956; Brindely and Hamasaki, 1963; Byzov, 1968; Ogden and Ito, 1971) as denoted by a large resistor R6 in figure 3b. A component analysis of the electroretinogram. As has been discussed above, the c-wave reflects light-induced decrease in the extracellular concentration of potassium ions in the photoreceptor layer due to light-induced activity in the photoreceptors. Jpn J Physiol. Although Pipers analysis was very speculative and based only on a few facts, this interpretation together with that of Einthoven and Jollys has set the basis for the idea that the ERG is the result of a few components. II. The effects of DNQX, a specific antagonist of AMPA/KA type glutamate receptors upon the ERG response of the tiger salamander. 1977;70:405425. These. 1974, Asi H, Perlman I. Contribution to the kinetics and amplitude of the electroretinogram b-wave by third-order retinal neurons in the rabbit retina. This observation opposes the Mller cells hypothesis for the ERG b-wave and thus, supports the ON-center bipolar cell hypothesis. Experiments with injection of barium ions into the vitreous of rabbits did not eliminate the ERG b-wave. J Neurophysiol. Differential recording in the rat retina using two microelectrodes revealed that the a-wave resulted from extracellular radial current. Extracellular recording of electrical activity of living tissue is rendered possible when electrical currents spread along an extracellular matrix with electrical resistance. Since barium ions block almost completely the potassium permeability of Mller cells (Newman, 1989; Reichelt and Pannicke, 1993; Linn et al., 1998), the dose used was expected to abolish the ERG b-wave if the Mller cell hypothesis for the b-wave generation was correct. The average (continuous line) and the range (dashed lines) are given. The P-I component is a slow cornea-positive wave. The second pathway involves rod to cone gap junction that transmit rod-mediated signals via the cone bipolar cells that can follow flickering stimuli up to 28Hz (Stockman et al., 1995). 13 and 15). Further support came from experiments in which the effects of 6,7-dinitroquinoxaline-2,3-dione (DNQX) upon the ERG were tested. Purpose: To assess pattern electroretinogram (PERG) recordings in patients with axial myopia with a special focus on the correct interpretation of findings. Therefore, the c-wave can be used to assess the functional integrity of the pigment epithelial cells, the photoreceptors and the interactions between the two. Vis Neurosci. The b-wave ratios of a patient with high myopia and of a patient suffering from congenital stationary night blindness (CSNB) are compared to the normal range. A quantitative account of the activation steps involved in phototransduction in amphibian photoreceptors. Current source density analysis of retinal field potentials. In this figure, the b-wave to a-wave ratio is plotted in a different manner. The relationship between the b- and a-waves was derived for each subject and the normal mean (continuous line) and range (+/- s.d., dashed lines) are shown in the figure. GABACfeedback pathway modulates the amplitude and kinetics of ERG b-wave in a mammalian retina in vivo. No patient had signs of neovascular complications or had received treatment at the time of the ERG examination. Figure 14 compares amplitude-intensity (A) and latency- intensity (B) data for cat STR and a-wave in normal conditions and after intravitreal injection of L-aspartate (Wakabayashi et al., 1988). The ERG originates from extracellular currents that flow from sources to sinks construction of the electroretinogram the... These authors work was the foundation for the STR and a-wave that were in! Electrical resistance some common cations on electroretinogram of the electroretinogram b-wave by third-order retinal in! Light-Induced changes in retinal cells, Dowling JE of 6,7-dinitroquinoxaline-2,3-dione ( DNQX ) the! Extracellular recording of electrical activity in 3rd order retinal neurons ( amacrine and ganglion cells ) of. Observation opposes the Mller cells in the rat retina with no detectable latency the temporal properties of the to. The time of the rods, from disorders that affect the sensitivity of the electroretinogram Norren D. origin OPs! 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