Vision is one of the most important of sensory systems used in the analysis of the surrounding world. Studies of the visual system have emphasized the antiquity and general conservative nature of information processing in the retina. Physiological and psychophysical studies have contributed to our growing understanding of the visual process, in large measure due to the accessibility of this sensory system to well-controlled external stimuli. The growing body of information in physiology and psychophysics has emphasized the need for more detailed information on the fundamental structure, biochemistry, and central organization of the visual system both in the adult and developing organism.
Our research utilizes a broad spectrum of anatomical and neurochemical methods, including: a) anterograde and retrograde pathway tracing; b) immunohistochemical and biochemical methods for the identification of specific transmitters, peptides, trophic factors, and their respective receptors; c) a single cell filling of identified neurons and quantitative morphometry; d) electron microscopic immunohistochemistry of identified neurons.
Our studies of retinal organization are directed towards identification of amacrine and ganglion cell transmitters, peptides, receptors, and their role in development of the eye and retina. The application of immunohistochemistry to studies of the retina has confirmed Cajal's original observations, based on studies using the Golgi method, of multiple subclasses of amacrine and ganglion cells. Our recent work has demonstrated a close correlation between the three- dimensional morphology of subclasses of amacrine cells and their respective transmitters/peptides and receptors.
Other projects include studies of the central pathways of each subtype of retinal ganglion cell and the comparative anatomy and evolution of central visual structures.
Karten, H.J. (1991). Homology and evolutionary origins of the 'Neocortex'. Brain, Behav. & Evolution 38: 264-272.
Karten, H.J., and Shimizu, T. (1991). Are visual hierarchies in the brains of the beholders? Constancy and variability in the visual system of birds and mammals. In: The Changing Visual System: Matura
Britto, L.R.G., Torrão, A.S., Hamassaki-Britto, D.E., Mpodozis, J., Keyser, K.T., Lindstrom, J.M., and Karten, H.J. (1994). Effects of retinal lesions upon the distribution of nicotinic acetylcholine
Dye, J.C., and Karten, H.J. (1996). An in vitro study of retinotectal transmission in the chick: Role of glutamate and GABA in evoked field potentials. Vis. Neurosci. 13: 747-758.
Mpodozis, J., Cox, K., Shimizu, T., Bischof, H.-J., Woodson, W., and Karten, H.J. (1996). GABAergic inputs to the nucleus rotundus (Pulvinar Inferior) of the pigeon (Columba livia). J. of Comp. Neurol