Author Type

Graduate Student

Date of Award

2007

Document Type

Dissertation

Publication Status

Version of Record

Submission Date

October 2026

Thesis/Dissertation Advisor [Chair]

Dong, Dawei

Abstract

In this dissertat ion, the early visual system is used to explore the role of efficiency in the general organization of the nervous system. Efficient representation theory predicts that neurons dynamically change their responses to changes in the environment in order to maintain their efficiency. To directly test the predication of this theory, a computational model and a neurophysiological experiment are used. Using a computational model, we investigate the sparseness of the response of filters at each stage of the model of the visual pathway. We find that the temporal bandpass filter and the rectification in each stage improves the efficiency of the response representation. Moreover, we find that ON/nonlagged responses carry more information than OFF/ lagged responses in signals with low signal-to-noise ratios. In the neurophysiological experiment, the response of LGN cells is measured and compared to their input from the retina in awake cats during free-viewing of natural time-varying images using quasi-intracellular recording technique. We find that the neural responses in the retina and the LGN are efficient. However, the LGN response is more efficient, sparser and less correlated than the retina's response, and it carries less information about eye movements than the retina's. As a result the LGN represents the visual world with fewer spikes. The LGN response changes with the variation of visual input. The temporal correlation of the visual input changes with saccade timing. Accordingly, the temporal receptive field of the LGN also changes in order to maintain the decorrelation of the LGN response regardless of the saccade. The retina-thalamic transmission changes during and after a saccade in order to transmit useful information to the visual cortex and decreases during a saccade in order to eliminate the variation of the visual input during a saccade. However, the transmission increases after a saccade to facilitate the transmission of new information due to the new gaze direction in the visual environment. The temporal receptive field of the LGN, derived from the efficacy of the thalamic transmission, is causal and bimodal. Such a receptive field decorrelates the visual input and improves the sparseness of the LGN response representation.

Extent

154 p.

Comments

Dissertation (Ph.D.)--Florida Atlantic University, 2007.|Dissertation (Ph.D.)--Florida Atlantic University, 2007.

Identifier

FA00000851

Format

pdf

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