The Projective Field of Retinal Bipolar Cells and Its Modulation by Visual Context

Abstract

The receptive field of a sensory neuron spells out allthe receptor inputs it receives. To understand a neuron's role in the circuit, one also needs to know its projective field, namely the outputs it sends to all downstream cells. Here we present the projective fields of the primary excitatory neurons in a sensorycircuit. We stimulated single bipolar cells of the salamander retina and recorded simultaneously from apopulation of ganglion cells. Individual bipolar cell signals diverge through polysynaptic pathways intoganglion cells of many different types and over surprisingly large distance. However, the strength and polarity of the projection depend on the celltypes involved. Furthermore, visual stimulation strongly modulates the bipolar cell projective field, in opposite direction for different cell types. In this way, the context from distant parts of the visual field can control the routing of signals in the inner retina.