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Proceedings Paper

Optical Imaging of fast light-evoked fast neural activation in amphibian retina
Author(s): Xin-Cheng Yao; John S. George
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Paper Abstract

High performance functional imaging is needed for dynamic measurements of neural processing in retina. Emerging techniques of visual prosthesis also require advanced methodology for reliable validation of electromagnetic stimulation of the retina. Imaging of fast intrinsic optical responses associated with neural activation promises a variety of technical advantages over traditional single and multi-channel electrophysiological techniques for these purposes, but the application of fast optical signals for neural imaging has been limited by low signal to noise ratio and high background light intensity. However, using optimized near infrared probe light and improved optical systems, we have improved the optical signals substantially, allowing single pass measurements. Fast photodiode measurements typically disclose dynamic transmitted light changes of whole retina at the level of 10-4 dI/I, where dI is the dynamic optical change and I is the baseline light intensity. Using a fast high performance CCD, we imaged fast intrinsic optical responses from isolated retina activated by a visible light flash. Fast, high resolution imaging disclosed larger local optical responses, and showed evidence of multiple response components with both negative- and positive-going signals, on different timescales. Darkfield imaging techniques further enhanced the sensitivity of optical measurements. At single cell resolution, brightfield imaging disclosed maxima of optical responses ~5% dI/I, while darkfield imaging showed maxima of optical responses exceeding 10% dI/I. In comparison with simultaneous electrophysiological recording, optical imaging provided much better localized patterns of response over the activated area of the retina.

Paper Details

Date Published: 22 February 2006
PDF: 8 pages
Proc. SPIE 6078, Photonic Therapeutics and Diagnostics II, 60782R (22 February 2006); doi: 10.1117/12.646840
Show Author Affiliations
Xin-Cheng Yao, Los Alamos National Lab. (United States)
John S. George, Los Alamos National Lab. (United States)

Published in SPIE Proceedings Vol. 6078:
Photonic Therapeutics and Diagnostics II
Kenton W. Gregory; Nikiforos Kollias; Reza S. Malek; Michael D. Lucroy; Henry Hirschberg; Brian Jet-Fei Wong; Eugene A. Trowers; Werner T.W. de Riese; Justus F. R. Ilgner; Steen J. Madsen; Lloyd P. Tate; Haishan Zeng; Guillermo J. Tearney; Bernard Choi, Editor(s)

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