MORPHOLOGICAL AND PHYSIOLOGICAL STUDY OF THE INTERACTIONS BETWEEN EXCITATION AND INHIBITION IN MUDPUPPY INNER RETINA.
Item
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Title
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MORPHOLOGICAL AND PHYSIOLOGICAL STUDY OF THE INTERACTIONS BETWEEN EXCITATION AND INHIBITION IN MUDPUPPY INNER RETINA.
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Identifier
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AAI8319754
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identifier
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8319754
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Creator
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COLEMAN, PAUL ANTHONY.
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Contributor
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Thomas E. Frumkes
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Date
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1983
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Animal Physiology
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Abstract
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Inner retinal neurons from Necturus maculosus were characterized by intracellular recording, receptive field mapping, current injection and by superfusing the following agents: gamma- Amino-n Butyric acid (GABA), glycine, their antagonists, and 2-amino- 4-phosphonobutyric acid (APB). They were also iontophoretically injected with Horseradish peroxidase (HRP) to be described by flat mount analysis. These measurements were verified by radial sections or computerized reconstruction and rotation. Amacrine and ganglion cells were categorized as either ON, OFF, or ON-OFF units based on excitatory response components. Additionally, some ON amacrine cells were observed to have perikarya displaced to the ganglion cell layer.;The axonal terminations of ON bipolars, as well as the dendrites of ON amacrine and ganglion cells were within the vitreal IPL, OFF amacrine and ganglion cells' processes projected toward the scleral IPL. Even though this difference between ON and OFF dendritic fields was statistically significant (p < 0.0005), overlap was observed. ON and OFF IPSPs were observed in some amacrine and ganglion cells, however these inhibitory potentials did not adhere to the morphological lamination pattern observed for EPSPs.;The interactions of excitatory and inhibitory potentials were studied by restricting attention toward ON cells whose photic response is dominated by a sustained depolarization, an initial burst of spikes and a homogeneous receptive field. These cells have different types of inhibitory inputs. In some cases both ON and OFF IPSPs were blocked by picrotoxin. For others, picrotoxin attenuates the ON IPSP and strychnine the OFF IPSP. Finally, strychnine causes the depolarization from the dark potential by 5-10 mV and attenuates the light evoked depolarization in some cells. These results suggests interactions with GABAergic ON and glycinergic OFF interneurons.;The underlying basis for OFF IPSPs in ON cells is problematic since these phenomena contradict the apparent laminar organization for excitation. The possibilities considered include, overlap between ON and OFF sublaminae and/or neurons not yet identified in mudpuppy which terminate in the "wrong" area of the IPL. In either event, a OFF IPSPs in ON cells suggests a modulatory mode of action.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Psychology
