How do ON-center bipolar cells respond to light?

ON-center bipolar cells play a crucial role in the process of visual signaling within the retina. When light is directed onto the photoreceptors (rods and cones) in the retina, they respond by hyperpolarizing, which decreases the release of the neurotransmitter glutamate. ON-center bipolar cells contain metabotropic glutamate receptors (mGluR6), which are inhibited by glutamate.

When the light reduces glutamate release from photoreceptors, the inhibition on ON-center bipolar cells is removed. As a result, these bipolar cells become depolarized. The depolarization of ON-center bipolar cells leads to the release of neurotransmitters onto the ganglion cells, which then transmit the visual information to the brain. This mechanism allows for the perception of brightness and contrast in the visual field.

Understanding this response is essential for grasping how the retina processes information under varying lighting conditions and how ON- and OFF-center pathways work in the visual system.