PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 10698021

Amplitude decrease of photopic ERG b-wave at higher stimulus intensities in humans.

M Kondo·C H Piao·A Tanikawa·M Horiguchi·H Terasaki·Y Miyake
View original source ↗Export metadata ↓

Abstract

PURPOSE: The b-wave of the human photopic electroretinogram (ERG) elicited by a short-flash increases in amplitude with increasing stimulus intensities at lower stimulus levels, but then decreases at higher stimulus intensities. The purpose of the present study was to explore this phenomenon in more detail, using short- and long-flash stimuli. METHODS: The intensity-response functions of the b-wave elicited by short- and long-flashes were compared from threshold to higher stimulus intensities in 5 normal subjects. Short- and long-flash ERGs were elicited under rod-saturating background levels using white light-emitting diodes built into a contact lens electrode. RESULTS: Whereas the amplitude of the short-flash b-wave decreased at higher intensities, the amplitude of the long-flash ERG b-wave did not decrease but plateaued. The long-flash ERG d-wave or OFF-response decreased at higher stimulus levels as did the short-flash elicited b-wave. CONCLUSIONS: Because it is widely accepted that the b-wave and the OFF-response d-wave interact to produce a single positive response, our results suggest that the decrease in the b-wave amplitude at high stimulus intensity is caused by the decrease of the d-wave at the higher stimulus intensities.

Explore related subjects

Adaptation, OcularAdultElectronic Data ProcessingElectroretinographyHumansMalePhotic StimulationReference ValuesRetinaComparative StudyJournal ArticleResearch Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

M Kondo, C H Piao, A Tanikawa, M Horiguchi, H Terasaki, Y Miyake. Amplitude decrease of photopic ERG b-wave at higher stimulus intensities in humans.. https://doi.org/10.1016/s0021-5155(99)00172-0

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2001

Temporal contrast adaptation in salamander bipolar cells.

This work investigates how the light responses of salamander bipolar cells adapt to changes in temporal contrast: changes in the depth of the temporal fluctuations in light intensity about the mean. Contrast affected the sensitivity of bipolar cells but not of photoreceptors or horizontal cells, suggesting that adaptation occurred in signal transfer from photoreceptors to bipolars. This suggestion was confirmed by recording from photoreceptor-bipolar pairs and observing a direct dependence of the gain of signal transfer on the contrast of the light input. After an increase in contrast, the onset of adaptation in the bipolar cell had a time constant of 1-2 sec, similar to a fast component of contrast adaptation in the light responses of retinal ganglion cells (Kim and Rieke, 2001). Contrast adaptation was mediated by processes in the dendrites of both on and off bipolars. The functional properties of adaptation differed for the two bipolar types, however, with contrast having a much more pronounced effect on the kinetics of the responses of off cells than on cells.

Adaptation, Ocular↗
PubMed2001

Rods are rods and cones cones, and (never) the twain shall meet.

More than 100 photopigment G protein-coupled receptors (opsins) have been sequenced and organized into six classes. Rod photoreceptors in various species have been found to express an opsin from one of the two rhodopsin classes, while cones express an opsin from one of the four remaining classes. It has now been discovered that salamander short-wavelength sensitive cones and green rods express the same opsin, while manifesting other features that classically distinguish rods from cones.

Adaptation, Ocular↗
PubMed2001

Motion processing in the macaque: revisited with functional magnetic resonance imaging.

A great deal is known about the response properties of single neurons processing sensory information. In contrast, less is understood about the collective characteristics of networks of neurons that may underlie sensory capacities of animals. We used functional magnetic resonance imaging to study the emergent properties of populations of neurons processing motion across different brain areas. Using a visual adaptation paradigm, we localized a distributed network of visual areas that process information about the direction of motion as expected from single-cell recording studies. However, we found an apparent discrepancy between the directional signals in certain visual areas as measured with blood oxygenation level-dependent imaging compared with an estimate based on the spiking of single neurons. We propose a hypothesis that may account for this difference based on the postulate that neuronal selectivity is a function of the state of adaptation. Consequently, neurons classically thought to lack information about certain attributes of the visual scene may nevertheless receive and process this information. We further hypothesize that this adaptation-dependent selectivity may arise from intra- or inter-area cellular connections, such as feedback from higher areas. This network property may be a universal principle the computational goal of which is to enhance the ability of neurons in earlier visual areas to adapt to statistical regularities of the input and therefore increase their sensitivity to detect changes along these stimulus dimensions.

Adaptation, Ocular↗