Thesis (M.S.)--Marquette University, 2009. / Access available to Marquette University only. Joseph Carroll, Kristina Ropella, Taly Gilat-Schmidt, Advisors.

Thesis (Ph.D.) - University of Queensland, 2004. / Includes bibliography.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 87-89).

Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 245-258).

Thesis (M. D.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--University of Chicago, Dept. of Ophthalmology and Visual Science, March 2001. / Includes bibliographical references. Also available on the Internet.

1. The spectral, spatial and temporal properties of receptive fields of dark-adapted, on-off retinal ganglion cells in the intact eye of the plaice, have been analysed by recording responses from their axon terminals in the superficial layers of the contra-lateral optic tectum with indium micro-electrodes. 2 Two cell-types have been identified on criteria of discharge patterns. The first type gives spectrally opponent "on-off" responses to coloured stimuli, with no subdivision of receptive fields into centre and periphery. On and "off" response-components are mutually inhibitory. The second type gives slow-adapting, "on-off" or "off" responses for different stimulus positions within the receptive field, with centre-surround or adjacent field patterns. Only "on-off" centre, off"-surround cells, or "off"-centre, "on-off" surround cells have been found, "On-off" centre cells exhibit mutual antagonism between field centre and surround. "Off"-centre cells possess inhibitory centres. This cell-type gives only weak opponent, or possibly non-opponent responses. 3. Moot cells of each type receive rod input in addition to input from cones. At stimulus intensities suprathreshold for cones, response-components give spectral maxima or more of four wavelength ranges; blue, 440-460 mum; blue-green, 470-490 mμ; green, 510-540 mμ; and orange, 560-590 mμ. No cello give red sensitivity maxima. At low stimulus intensities all cells with rod input give a single spectral peak between 520 and 530 mμ.

Consideration of available evidence suggests that primate vision utilises two parallel cortical pathways to process visual information. The ventral pathway processes form or shape information, while the dorsal pathway processes motion information. In the macaque monkey, the superior temporal sulcus in the temporal lobe is one of the few cortical areas that receives input from both these pathways. In this thesis recordings from visually responsive neurons in the macaque superior temporal sulcus are described. The cell response properties of three cell groups are investigated. One cell population show selectivity for the sight of static images of particular views of the body. The second group of cells shows selectivity for the sight of objects moving in the environment, independent of the object's form. The final group of cells show selectivity for particular views of the body providing that they are moving in particular directions. The responses from these three groups of cell types are subjected to an analysis technique that allows insights into possible computational processes underlying the observed neural selectivity's. In particular, it is argued that the primate visual system processes form information primarily in a feedforward way, a property few computational models of visual processing employ. These data are combined with data from other studies to produce a speculative outline for a biologically plausible model of primate visual form processing. The recordings also revealed cell responses to walking bodies that showed a remarkable selectivity for "structure from motion". It is suggested that this selectivity is developed by associative learning between the initially separate form and motion inputs. Investigation of the integration of form and motion information onto single cells indicated a hitherto unforeseen problem: a temporal asynchrony between the arrival times of form and direction information. This asynchrony indicates that previously proposed mechanisms for binding of information about the same object are incorrect.

The study examined the importance of (1) component parts, (2) view, (3) orientation and (4) size in the neural encoding of the sight of a complex object in the temporal cortex of the macaque. Studies focused on cells selectively responsive to the sight of the head/body but unresponsive to control stimuli. (1) Cells responsive to the static whole body were tested with two component parts of the body. 44% (29/66) of cells responded to the whole body and to one of the two body regions tested: 23 to the head; 6 to the body. 36% (24/66) responded independently to both regions of the body when tested in isolation. The remaining cells were selective for the entire body and unresponsive to component parts. Similar selectivity for component parts was observed amongst cells responsive to moving heads/bodies (18 cells tested). (2) 90% (66/73) of cells (selectively responsive to static or moving head/bodies) tested were sensitive to perspective view (viewer-centred). Comparable levels of view sensitivity were found for responses to the whole body and its parts. Contrary to some influential models of object recognition these results indicate view-specific processing for both the appearance of separate object components and for integration of information across components. (3) The majority of cells tested (18/25, 72%) were selectively responsive to a particular orientation in the picture plane of the static whole body stimulus. 7 cells generalised across all orientations (4 cell with pure generalisation; 3 cells with superimposed orientation tuning). Of all cells sensitive to orientation, the majority (15/21, 71%) were tuned to the upright image. (4) The majority of cells tested (81%, 13/16) were selective for a particular stimulus size. The remaining cells (3/16) showed generalisation across a 4 fold decrease in size from life-sized. Interestingly, all size sensitive cells were tuned to life-sized stimuli. These results do not support previous suggestions that cells responsive to the head and body are selective to the view but generalise across orientation and size. Here, extensive selectivity for size and orientation is reported. It is suggested that object part, view, orientation and size specific responses might be pooled to obtain generalising responses. Experience appears to affect neuronal coding in two ways: a) Cells become selective for multiple object components due to spatial and temporal association between parts; and b) more cells become tuned to views, orientations and image sizes commonly experienced.