Do horizontal cells depolarize or hyperpolarize in response to light?

Horizontal cells in the retina play a critical role in the processing of visual information. When light enters the eye, it causes photoreceptors (rods and cones) to hyperpolarize, which in turn leads to a decrease in the neurotransmitter release (glutamate). Horizontal cells receive input from these photoreceptors and respond to changes in glutamate levels.

In response to the hyperpolarization of photoreceptors caused by light, horizontal cells also hyperpolarize. This hyperpolarization is due to the reduction in glutamate, which normally stimulates the horizontal cells through excitatory synapses. As the photoreceptors release less glutamate, the horizontal cells cease to be excited, resulting in their own hyperpolarization. This response is essential for the lateral inhibition process that allows for contrast enhancement and helps in the formation of clear visual images.

Thus, hyperpolarization of horizontal cells is an integral part of the retinal response to light, enabling the proper modulation of signals that help maintain visual acuity.