Identification of defects in specific parallel "channels" of the human visual system
Wolf, J. E. (1996). Identification of defects in specific parallel "channels" of the human visual system. (Unpublished Doctoral thesis, City, University of London)
Abstract
Chapter 1 is a general introduction to the work of the thesis. The anatomy and physiology of the visual system is described, especially in relationship to the primate eye and visual pathway. The description concentrates on the distinction between of primate ganglion cells types, M and P, and their projections to the lateral geniculate nucleus, and the visual cortex. An account is given of psychophysical methods, and how quantities defined by such experiments, such as sensitivity, incremental sensitivity, contrast sensitivity, etc. may be related to activity of single cells, determined by physiologists. The evidence for separate channels for spatial, temporal, achromatic and chromatic channels in the visual system is reviewed, and theories of possible neural correlates are critically discussed.
Chapter 2 introduces some preliminary experiments, on the visual effect seen on viewing a slowly rotating striped pattern. The subsequent analysis demonstrates that the effect displays the temporal frequency response of the eye (illustrated by papers 1 and 2).
Chapter 3, illustrated by Paper 3, discusses the complex appearance of the 'rotating stripes’, and how it provides a direct display of the underlying channels. It is illustrated with a computer simulation of the component channel images.
Chapter 4 shows the abnormalities in perception of rotating stripes found in cases of optic neuritis, and relates them to the loss of the ‘transient’ channel.
Chapter 5 ( paper 4) deals with the psychophysics of two diseases, Melanoma-Associated Retinopathy, in which it is found that there is a highly selective loss of the achromatic M- pathway, and another condition which is its converse, a nutritional amblyopia in which the P-cell pathway is selectively affected.
The results are reviewed and discussed in the final chapter.
| Publication Type: | Thesis (Doctoral) |
|---|---|
| Subjects: | R Medicine > RZ Other systems of medicine |
| Departments: | School of Health & Psychological Sciences > Optometry & Visual Sciences School of Health & Psychological Sciences > School of Health & Psychological Sciences Doctoral Theses Doctoral Theses |
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