Bipolar Cell

Introduction

Bipolar cells are a class of neurons that are primarily utilized as sensory afferents, carrying signal from the various sense organs towards higher level processing areas. Within the retina, bipolar cells act as the signal couriers between the photoreceptors that react to light stimuli and the ganglion cells that carry these signals out of the eye and into the cortex. Bipolar cells are so-called because they have two polar extensions that protrude from opposite ends of the soma. One of these extensions extends to a single photoreceptor (either a rod or cone) while the other delivers the processed signal to the dendritic arbors of the ganglion cells.

Processing Activity

The ON and OFF center circuits within the retina are a product of the either sign-conserving or sign-reversing synapse that the bipolar cell shares with its paired photoreceptor. Sign-conserving synapses result in an OFF center while sign-reversing synapses produce an ON center. The surround portion of the center/surround functionality is dependent upon the aggregate signals from surrounding horizontal and amacrine cells.

Electrophysiology

• Sign-conserving vs. Sign-reversing details