How can we assay the health of photoreceptors and bipolar neurons?
One can now routinely assay the health of the photoreceptors in humans and animal models with electroretinogram (ERG) techniques. These techniques can be traced to 1990, when David Birch and I showed that the same mathematical model fitted to recordings from single primate receptors fitted the leading edge of the human rod a-wave. (ref 4 below) In our 1994 paper in IOVS (ref 2), we laid out the logic of using this approach to study receptor activity in humans and animal models. The success of this model encouraged us to go on to show that the human ERG could be used to: measure cone photoreceptor activity (e.g. ref 3); and to isolate and study rod On-bipolar cell activity (ref 4). These techniques for studying the responses of human receptors and rod On-bipolar cells have been used in many human and animal studies during the last 20 years. In addition, we have given our software for analyzing a-waves to more than 35 groups in 13 countries, Brazil, Canada, Chile, Denmark, England, Germany, Greece, Japan, Mexico, Spain, Singapore, Sweden, and the United States.
Relevant Recent Reviews/Papers:
- Hood DC, Birch DG. The a-wave of the human ERG and rod receptor function. Invest Ophthalmol Vis Sci. 1990;31(10):2070-2081. PMID: 2211004
- Hood DC, Birch DG. Rod phototransduction in retinitis pigmentosa: Estimation and interpretation of parameters derived from the rod a-wave. Invest Ophthalmol Vis Sci. 1994:35(7):2948-61. PMID: 8206712
- Hood DC, Birch DG. Human cone receptor activity: The leading edge of the a-wave and models of receptor activity. Vis Neurosci. 1993;10(5):857-71. PMID: 8217936
- Hood DC, Birch DG. The b-wave of the scotopic (rod) ERG as a measure of the activity of human on-bipolar cells. J Opt Soc Amer. 1996;13(3):623-33. PMID: 8627419