Which ERG wave reflects the activity of bipolar and Muller cells?

The B wave of the electroretinogram (ERG) is primarily associated with the activity of bipolar and Müller cells within the retina. The B wave occurs after the A wave in the ERG and represents a summation of the depolarizing responses from the bipolar cells as well as the contributions from Müller cells.

When photoreceptors (rods and cones) are stimulated by light, they undergo hyperpolarization, which affects the synaptic transmission to bipolar cells. The bipolar cells then proliferate signals that are relayed to ganglion cells. The B wave reflects this process, indicating how the light stimulus affects the inner retina, particularly through the activity of bipolar cells.

Müller cells, as the principal glial cells in the retina, serve multiple functions including maintaining the structural integrity of the retina, assisting in the metabolic support of neurons, and helping with the buffering of retinal ion concentrations. Their activity also contributes to the amplitude and the shape of the B wave.

Understanding the ERG and its components is essential in clinical settings, particularly in diagnosing retinal pathologies. The distinct phases of the ERG, including the A and B waves, are crucial for identifying specific abnormalities related to different cell types in the retina.