Retinal Ganglion Cells Can Rapidly Change Polarity from Off to On
Figure 3
A Polarity-Reversing Ganglion Cell Receives On Inputs from the On Bipolar Pathway
(A and B) Two possible circuits underlying On-type responses of ganglion cell, involving photoreceptors (P), bipolar cells (B), amacrine cells (A), and ganglion cells (G), linked by excitatory (closed circles) or inhibitory (open circles) synapses. (A) The ganglion cell is excited by both On-type and Off-type bipolar cells. Application of 2-amino-4-phosphono-butyrate (APB) blocks the On pathway at the photoreceptor synapse. (B) The ganglion cell is excited by Off bipolars, and also inhibited by Off amacrine cells. This On pathway is not affected by APB.
(C) Application of APB abolishes polarity reversal. Top: modulation of the firing rate and the linear filter by the peripheral shift, displayed as in Figure 2C for a sample ganglion cell. Bottom: same as top panel, after application of 150 μM APB.