What cells are responsible for the a-wave in an ERG?

What cells are responsible for the a-wave in an ERG?

• A. Bipolar cells
• B. Müller cells
• C. Retinal pigment epithelium
• D. Photoreceptors

Answer: (D)

The a-wave of an ERG is produced by the photoreceptors in the outer retina. When light hits the retina, photoreceptors hyperpolarize because the light-activated cascade closes the cGMP-gated channels, reducing inward current. This rapid change in the outer retinal current creates the initial negative-going deflection—the a-wave. The later, positive part of the ERG (the b-wave) mainly reflects activity in the inner retina, especially the bipolar cells, with Müller cells contributing to the overall signal; the retinal pigment epithelium contributes to other components like the c-wave rather than the a-wave. So, photoreceptors are the best answer because they are the primary generators of the a-wave.

The a-wave of an ERG is produced by the photoreceptors in the outer retina. When light hits the retina, photoreceptors hyperpolarize because the light-activated cascade closes the cGMP-gated channels, reducing inward current. This rapid change in the outer retinal current creates the initial negative-going deflection—the a-wave. The later, positive part of the ERG (the b-wave) mainly reflects activity in the inner retina, especially the bipolar cells, with Müller cells contributing to the overall signal; the retinal pigment epithelium contributes to other components like the c-wave rather than the a-wave. So, photoreceptors are the best answer because they are the primary generators of the a-wave.