Organization of the retina of the mudpuppy, Necturus maculosus. II. Intracellular recording.

Abstract

the optic nerve, it has been possible to specify many of the functions performed bv the vertebrate retina. These include brightness detection (16, 18, 27), centersurround contrast detection (1, 8, 20, 23), and motion detection (3, 4, 26-28). It has not been possible, however, to determine how the retina organizes the visual message recorded at the optic nerve, primarily because intracellular recording from single cells distal to the ganglion cells has been difficult. Detailed structural studies of the vertebrate retina, such as the one in the preceding paper (14), provide a framework within which the functional organization of the retina can be described. The anatomical studies show a limited number of clearly defined synaptic structures at which interaction between specific neurons can take place. In this paper we shall describe the intracellularly recorded response characteristics of each type of neuron in a vertebrate retina, and then relate the response of each neuron to the responses of those neurons to which it is synaptically coupled. By following the responses through the synaptic pathways, we can begin to describe how information from the visual field is abstracted and encoded in the retina. Intracellular recording throughout most retinas has been difficult because even the finest available micropipettes fail to penetrate the small retinal neurons consistently without damage. Bortoff (5-7) showed that this difficulty could be overcome by recording in an animal with larger retinal neurons: the mudpuppy, Nectwus maculosus. As described in the preceding paper (14),