Photoreceptors are depolarized in the dark and are hyperpolarized by light and thus fewer transmitter molecules are released in the light than in the dark. In the out plexiform layer, each photoreceptor is in synaptic contact with bipolar and horizontal cells. Bipolar cells create the direct pathway from photoreceptors to ganglion cells; horizontal cells feed information laterally in the outer plexiform layer to influence the activity of neighbouring bipolar cells and photoreceptors. Bipolar cells can be categorized into two classes: off bipolar cells (glutamate-gated channels mediating depolarizing epsp from na+ influx) and on bipolar cells (g-protein-coupled receptors and respond to glutamate by hyperpolarizing). Note: off and on refer to whether these cells respond to light off (more glutamate) or light on (less glutamate). Each bipolar cell receives direct synaptic input from a cluster of photoreceptors. The receptive field of a bipolar cell is the area of the retina that, when stimulated with light, changes the cell"s membrane potential.