Mitchell Glickstein

Retinoscopy and Eye Size

Retinoscopy was performed on animals with different sized eyes, all of whom appeared hypermetropic. The data were well fitted by an equation of the form y = kx-2 where y is refractive error in diopters, and x is the corneo-retinal length of the eye. Apparent hypermetropia may be due to the reflection from the inner surface of the retins.

Receptors in the monochromat eye

Abstract We studied the retina of a monochromat whose vision had been tested extensively during his life. Cones were present but in sharply reduced numbers from those in the normal eye. There were no receptors in the fovea. Results are consistent with psychophysical observation on this subject and other monochromats. Monochromats show some evidence of cone functioning when tested with flicker and dark adaptation, but they have no color vision and have poor acuity. A sharply reduced number of cones might produce all of these symptoms.

Corticopontine projections of the lateral suprasylvian cortex: De-emphasis of the central visual field

Layer V pyramidal cells of the cat lateral suprasylvian visual areas project to the pontine nuclei. Although all 6 of the suprasylvian visual areas project to the pons, the densest projections are from 3 areas: anterior medial lateral suprasylvian (AMLS), posterior medial lateral suprasylvian (PMSL) and ventral lateral suprasylvian (VLS). The organization of the corticopontine pathway from one of these areas (PMLS) suggests a disproportionate representation of the peripheral visual fields. This pattern of projection would serve to de-emphasize the central visual field.

Visual Control of Movement: The Circuits Which Link Visual to Motor Areas of the Brain with Special Reference to the Visual Input to the Pons and Cerebellum

Publisher Summary This chapter discusses the neural basis of visually guided movement especially in relation to the possible role of the pons and cerebellum. Visual input to the cerebellum from the forebrain and brainstem is relayed in large part by way of the pontine nuclei. The chapter presents a study of the receptive field properties of antidromically identified corticopontine cells. . The corticopontine cells are sensitive to multiple-spot targets moving in specific directions over large portions of the visual field. These properties are consistent with a visuomotor function for the cortico–ponto–cerebellar pathway. The visual cells in the dorsolateral nucleus have receptive field properties that are similar to cells in the superficial laminae of the superior colliculus. The large number of dorsolateral pontine cells that prefer single-spot targets contrast with the multiple-spot preference of medial pontine cells that receive their input from the visual cortex.

Vision in Monkeys with Lesion of the Striate Cortex

Recent studies have made major advances in the methods and techniques for determination of sensory capacities of animals. Our confidence in the results of such studies is strengthened by the replicability of thresholds from animal to animal, and the frequent similarity between measures of animal and human sensory functions. One natural application of animal psychophysics is to use the same methods for evaluation of sensory capacities in animals with lesions, in the expectation that such studies may help towards understanding the nature of sensory processing by the brain. For example, if a sense organ projects independently to two or more places in the brain, we might learn more about possible differential functions of these central structures by ablating one or the other, and testing residual sensory capacity. In the case of vision, we might destroy the striate cortex or the superior colliculus and attempt to determine the nature of the visual loss. Along with anatomic and physiologic data, behavioral study of lesion effects would help in analysis of the functional capacity of these two parallel visual pathways. We might determine the effects of such lesions on photopic and scotopic brightness thresholds, visual acuity, and the ability of the animals to discriminate form, color, and movement, and thus evaluate the capacity of the surviving visual structures. We must recognize, of course, that in the example given, the geniculocortical and collicular circuits are not completely independent.