ON-OFF amacrine cells in cat retina.
We studied the morphology, photic responses, and synaptic connections of ON-OFF amacrine cells in the cat retina by penetrating them with intracellular electrodes, staining them with horseradish peroxidase, and examining them with the electron microscope. In a sample of seven cells, we found two different morphological types: the A19, which ramifies narrowly in stratum 2 (sublamina a) of the inner plexiform layer, and the A22, which ramifies mostly in stratum 4 (sublamina b) but extends some dendrites to sublamina a. Both of these cell types have axon-like processes that extend > 800 microns from the conventional dendritic arbor. ON-OFF amacrine cells in our sample had receptive fields (1.7 +/- 0.3 mm diameter) that were broader than their dendritic arbors (425 +/- 35 microns diameter) and that extended over the region of axon-like processes. In addition, we found many features in common with ON-OFF amacrine cells in poikilotherm vertebrates: a broad receptive field without surround antagonism, two sizes of spike-like events, narrow dynamic range (1 log unit intensity), and excitatory postsynaptic potentials at light on and light off. Two A19 amacrine cells were examined in the electron microscope: most synaptic inputs (93 and 76%, respectively) to either cell were from amacrine cells, with minor inputs from cone bipolar cells. Synaptic outputs were to bipolar, amacrine, and ganglion cells, including the OFF-alpha cell.
Freed
M A
MA
National Institute of Neurological Disorders and Stroke, Maryland 20892, USA.
Pflug
R
R
Kolb
H
H
Nelson
R
R
D000818:Animals; D001369:Axons / Q000502:physiology / Q000648:ultrastructure; D002415:Cats; D003712:Dendrites / Q000502:physiology / Q000648:ultrastructure; D004594:Electrophysiology; D005074:Evoked Potentials, Visual / Q000502:physiology; D006651:Histocytochemistry; D006735:Horseradish Peroxidase; D008854:Microscopy, Electron; D010775:Photic Stimulation; D012160:Retina / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology; D013569:Synapses / Q000502:physiology / Q000648:ultrastructure; D014794:Visual Fields / Q000502:physiology
D006735:Horseradish Peroxidase