The electroretinogram b-wave is a prominent positive-going component of many light-evoked electroretinography traces, associated strongly with the activity of ON retinal bipolar cells. It is an extracellular tissue-level signal, rather than the intracellular membrane potential of one photoreceptor or one bipolar cell. Its appearance and amplitude depend on the stimulus and recording conditions.[ref]
B-wave of the electroretinogram. A reflection of ON bipolar cell activity by Richard A. Stockton and Malcolm M. Slaughter. Abstract: intraretinal fields, pharmacological isolation and ON bipolar contribution.
The assignment was tested by perturbing retinal pathways. In amphibian preparations, APB suppressed ON bipolar responses and removed the b-wave; treatments suppressing OFF-related responses removed the light-offset d-wave while preserving the b-wave. Recording potassium changes along with field responses helped link the electrical component to a specific functional pathway.[ref]
B-wave of the electroretinogram. A reflection of ON bipolar cell activity by Richard A. Stockton and Malcolm M. Slaughter. Selective pharmacological comparisons and extracellular potassium measurements.
A later molecular perturbation supplied independent evidence. Mice lacking TRPM1 retained a normal rod a-wave but lacked the b-wave, while direct bipolar-cell recordings supported disruption of postsynaptic ON signaling. A signal from the early photoreceptor stage can therefore persist when the later response is lost.[ref]
For an illustrative trace, a preceding trough at and a positive peak at are separated by . That trough-to-peak difference differs from the peak's displacement above a zero baseline. Always state the amplitude convention; these invented values are not diagnostic limits or data from either study.
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