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VISUAL INFORMATION PROCESSING BY
THE FEEDFORWARD AND FEEDBACK INPUTS
TO THE LATERAL GENICULATE NUCLEUS
by
Vishal S. Vaingankar
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(NEUROSCIENCE)
May 2011
Copyright 2011 Vishal S. Vaingankar
Object Description
| Title | Visual information processing by the feedforward and feedback inputs to the lateral geniculate nucleus |
| Author | Vaingankar, Vishal S. |
| Author email | vaingank@usc.edu; vishalsv19@gmail.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Neuroscience |
| School | College of Letters, Arts and Sciences |
| Date defended/completed | 2011-03-18 |
| Date submitted | 2011 |
| Restricted until | Restricted until 02 May 2012. |
| Date published | 2012-05-02 |
| Advisor (committee chair) | Hirsch, Judith |
| Advisor (committee member) |
Sommer, Fritz Sampath, Alapakkam Grzywacz, Norberto |
| Abstract | All the visual information captured by the retina is relayed through the visual thalamus before reaching the cortex. Traditionally the lateral geniculate nucleus (LGN) has been described as the relay station that passively transmits visual information. This simplistic view of the LGN may not be justified given the complexity of local (intrinsic), and extrinsic circuits that are capable of modulating its output. For example, even the feedforward connections are complicated; relay cells often receive inputs from multiple retinal ganglion cells. This retinogeniculate convergence challenges the conventional notion of one to one mapping from retina to thalamus and adds additional level of complexity to the thalamic processing. Moreover, the LGN receives considerable feedback inhibition from the inhibitory cells in the perigeniculate nucleus (PGN) of the thalamic reticular formation. Given the anatomical composition and location of PGN, Francis Crick called it the guardian of the thalamus.; This thesis addresses both feedback and feedforward sources of inputs to the relay cells. In order to understand how the PGN influences relay cells, it is imperative that we first understand the response properties and receptive field structure of its component cells. In chapter two I show that neurons in the perigeniculate are often selective for higher order features of the stimulus and process their inputs using complex nonlinear mechanisms. Further by using a simple model I discuss how these features might pool their ON and OFF inputs.; I further explored response properties in the PGN by asking if specific visual features caused reticular cells to change their firing patterns from burst to tonic modes.My results showed that bursts encode dramatic changes in luminance whereas the tonic spikes encode the more subtle shifts in luminance. Further, I describe a model of how visually driven changes in firing mode in the PGN might facilitate bursting in the LGN.; Lastly, using in vivo patch recordings in relay cells and computational methods, I show that multiple retinal ganglion cells often converge onto a single relay cell and, collectively, shape its receptive field. I propose a possible functional role of this retinogeniculate convergence.; Altogether the work presented in this thesis contributes to our understanding of both feedforward and feedback circuits in the LGN and how they are likely to influence the information that cortex receives. |
| Keyword | lateral geniculate nucleus; perigeniculate nucleus; feedback inhibition; thalamic reticular nucleus |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m3825 |
| Rights | Vaingankar, Vishal S. |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | http://www.usc.edu/isd/libraries/services/ask_a_librarian/email/ |
| Filename | etd-Vaingankar-4471 |
| Archival file | uscthesesreloadpub_Volume26/etd-Vaingankar-4471.pdf |
Description
| Title | Page 1 |
| Full text | VISUAL INFORMATION PROCESSING BY THE FEEDFORWARD AND FEEDBACK INPUTS TO THE LATERAL GENICULATE NUCLEUS by Vishal S. Vaingankar A Dissertation Presented to the FACULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (NEUROSCIENCE) May 2011 Copyright 2011 Vishal S. Vaingankar |
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