NBEO Ocular Physiology Practice Exam 2025 – Complete Exam Prep

OFF-center ganglion cells are specialized neurons in the retina that respond to changes in light intensity, specifically to decreases in light levels in their receptive fields. When light falls on the OFF-center region of these cells, they undergo hyperpolarization, which results in a decrease in their firing rate. This is due to the fact that OFF-center ganglion cells are associated with regions of the retina that have a direct connection to photoreceptors (rods and cones) which release glutamate in response to light. Glutamate has different effects on ionotropic receptors based on whether they are part of an ON or OFF pathway.

In the case of OFF-center ganglion cells, the photoreceptors release less glutamate when illuminated, leading to a hyperpolarization of the bipolar cells that synapse onto these ganglion cells. Consequently, the OFF-center ganglion cells become less depolarized and cease firing as much, demonstrating their characteristic response to light. This process is crucial for visual processing as it allows the retina to convey a wide range of light stimuli to the brain, enhancing contrast and aiding in object detection.