The parietal eye of lizards extracts, processes and sends to the brain information about the light striking its retina. The retina lacks bipolar cells and has only one plexiform layer. Photoreceptors synapse directly onto ganglion cells. Afferent signal flow is modified by the activity of efferent fibers. It is proposed to identify the morphological and physiological substrates for visual information processing in this retina. The morphological methods to be employed include: 1) three-dimensional reconstruction of serial electron micrographs to identify synaptic connectivity, 2) immunocytochemistry to localize possible transmitter substances, and 3) horseradish peroxidase histochemistry to differentiate neural connectivity. Both extracellular and intracellular recording techniques will be utilized to examine: 1) the physiological characteristics of photoreceptors and neurons and, 2) the information processing of synaptic connections. This proposal focuses on the parietal eye as a sensory and organ involved in visual information processing. The relatively simple neural organization of the parietal eye contrasts with the extremely complex organization of the retina. I expect that a close analysis of the parietal eye will reveal similarities and differences which viewed in comparative light may reveal important and generalizable features of sensosy processing. The health-related aspects of this work are indirect, deriving mainly from an increased understanding of basic mechanisms of retinal function.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY003359-07
Application #
3257691
Study Section
Visual Sciences A Study Section (VISA)
Project Start
1979-09-01
Project End
1987-08-31
Budget Start
1985-09-01
Budget End
1986-08-31
Support Year
7
Fiscal Year
1985
Total Cost
Indirect Cost
Name
Syracuse University
Department
Type
DUNS #
City
Syracuse
State
NY
Country
United States
Zip Code
13210
Solessio, E; Engbretson, G A (1999) Electroretinogram of the parietal eye of lizards: photoreceptor, glial, and lens cell contributions. Vis Neurosci 16:895-907
Ahmed, J; Engbretson, G A (1993) Disk shedding in the absence of a pigment epithelium in the lizard parietal eye. Vision Res 33:2637-43
Engbretson, G A; Linser, P J (1991) Glial cells of the parietal eye: structural and biochemical similarities to retinal Muller cells. J Comp Neurol 314:799-806
Engbretson, G A; Anderson, K J (1990) Neuronal structure of the lacertilian parietal eye, I: A retrograde label and electron-microscopic study of the ganglion cells in the photoreceptor layer. Vis Neurosci 5:395-404
Engbretson, G A; Anderson, K J; Wu, J Y (1988) GABA as a potential transmitter in lizard photoreceptors: immunocytochemical and biochemical evidence. J Comp Neurol 278:461-71
Engbretson, G A; Battelle, B A (1987) Serotonin and dopamine in the retina of a lizard. J Comp Neurol 257:140-7
Engbretson, G A; Battelle, B A (1985) Identification of putative neurotransmitters in the lizard parietal eye. Invest Ophthalmol Vis Sci 26:670-8