Dark adaptation recovery of human rod bipolar cell response kinetics estimated from scotopic b-wave measurements
Date
2008
Authors
Cameron, Allison
Miao, Liang
Ruseckaite, Rasa
Pianta, M.J
Lamb, Trevor
Journal Title
Journal ISSN
Volume Title
Publisher
Cambridge University Press
Abstract
We recorded ganzfeld scotopic ERGs to examine the responses of human rod bipolar cells in vivo, during dark adaptation recovery following bleaching exposures, as well as during adaptation to steady background lights. In order to be able to record responses at relatively early times in recovery, we utilized a 'criterion response amplitude' protocol in which the test flash strength was adjusted to elicit responses of nearly constant amplitude. In order to provide accurate and unbiased measures of response kinetics, we utilized a curve-fitting procedure to fit a smooth function to the measured responses in the vicinity of the peak, thereby extracting both the time-to-peak and the amplitude of the responses. Following bleaching exposures, the responses exhibited both desensitization and accelerated kinetics. During early post-bleach recovery, the flash sensitivity and time-to-peak varied according to a power-law expression (with an exponent of 6), as found in the presence of steady background light. This light-like phenomenon, however, appeared to be set against the backdrop of a second, more slowly recovering 'pure' desensitization, most clearly evident at late post-bleach times. The post-bleach 'equivalent background intensity' derived from measurements of flash sensitivity faded initially with an S2 slope of ∼0.24 decades min-1, and later as a gentle S3 tail. When calculated from kinetics, the results displayed only the S2 slope. While the recovery of rod bipolar cell response kinetics can be described accurately by a declining level of opsin in the rods, the sensitivity of these cells is reduced further than expected by this mechanism alone.
Description
Keywords
Keywords: opsin; adult; article; B wave; bleaching; cell kinetics; curve fitting; dark adaptation; desensitization; electroretinography; human; human cell; in vivo study; molecular mechanics; night vision; priority journal; retina rod outer segment; sensitivity ana
Citation
Collections
Source
Journal of Physiology
Type
Journal article
Book Title
Entity type
Access Statement
License Rights
Restricted until
2037-12-31
Downloads
File
Description