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Using the light spectrum to understa...

Figueiro, Mariana Gross.

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Using the light spectrum to understand better the mechanisms of the circadian system.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Using the light spectrum to understand better the mechanisms of the circadian system./
Author:	Figueiro, Mariana Gross.
Description:	125 p.
Notes:	Adviser: Robert H. Parsons.
Contained By:	Dissertation Abstracts International65-02B.
Subject:	Biology, Neuroscience. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3122985
ISBN:	9780496702992

Using the light spectrum to understand better the mechanisms of the circadian system.
Figueiro, Mariana Gross.

Using the light spectrum to understand better the mechanisms of the circadian system. - 125 p.

Adviser: Robert H. Parsons.

Thesis (Ph.D.)--Rensselaer Polytechnic Institute, 2004.

Regulation of circadian functions by light in mammals is mediated through the retina, and evidence has gathered that the cone and rod photoreceptors are supplemented by a novel photopigment, most likely a vitamin-A based opsin, called melanopsin, present in a subset of photosensitive retinal ganglion cells. Recently, much work has been done to probe the absolute and spectral sensitivities of the circadian system. A main question still remains, namely, does the circadian system respond to light in an additive manner, or is a spectral opponent mechanism at post-receptoral level also involved? This thesis describes three experiments extending earlier work using techniques adapted from visual psychophysics to further probe the spectral sensitivity of circadian phototransduction and the possibility of spectral opponency in humans.

ISBN: 9780496702992Subjects--Topical Terms:

1017680
Biology, Neuroscience.

Using the light spectrum to understand better the mechanisms of the circadian system.
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005 20110921
008 110921s2004 eng d
020 $a 9780496702992
035 $a (UMI)AAI3122985
035 $a AAI3122985
040 $a UMI $c UMI
100 1 $a Figueiro, Mariana Gross. $3 1294801
245 1 0 $a Using the light spectrum to understand better the mechanisms of the circadian system.
300 $a 125 p.
500 $a Adviser: Robert H. Parsons.
500 $a Source: Dissertation Abstracts International, Volume: 65-02, Section: B, page: 0609.
502 $a Thesis (Ph.D.)--Rensselaer Polytechnic Institute, 2004.
520 $a Regulation of circadian functions by light in mammals is mediated through the retina, and evidence has gathered that the cone and rod photoreceptors are supplemented by a novel photopigment, most likely a vitamin-A based opsin, called melanopsin, present in a subset of photosensitive retinal ganglion cells. Recently, much work has been done to probe the absolute and spectral sensitivities of the circadian system. A main question still remains, namely, does the circadian system respond to light in an additive manner, or is a spectral opponent mechanism at post-receptoral level also involved? This thesis describes three experiments extending earlier work using techniques adapted from visual psychophysics to further probe the spectral sensitivity of circadian phototransduction and the possibility of spectral opponency in humans.
520 $a In experiment 1, human adult males were exposed to four lighting conditions (two illuminances and two spectral power distributions) during four nighttime experimental sessions. In experiments 2 and 3, human adult males were exposed to two lighting conditions (one illuminance and two spectral power distributions) during two nighttime experimental sessions.
520 $a Results support the inference that the circadian system responds to light in a non-additive, spectral opponent manner. No additive model incorporating opsin photopigments either alone or in combination could explain the results, but a model incorporating a spectral opponent mechanism was consistent with the present data as well as neuroanatomy and neurophysiology.
520 $a A secondary goal of this thesis was to determine if the spectral sensitivity of the circadian system changes throughout the night. It is known that the absolute sensitivity of the circadian system changes over the course of 24 hours, but it is still unknown whether its spectral sensitivity, measured through melatonin suppression, also changes throughout the solar day. Data were highly variable, but suggest a change in spectral sensitivity throughout the night. More work is needed before it is proven that the spectral sensitivity of the circadian system changes over the course of the night, but it is certainly new and important line of inquiry.
590 $a School code: 0185.
650 4 $a Biology, Neuroscience. $3 1017680
650 4 $a Biophysics, General. $3 1019105
690 $a 0317
690 $a 0786
710 2 0 $a Rensselaer Polytechnic Institute. $3 1019062
773 0 $t Dissertation Abstracts International $g 65-02B.
790 $a 0185
790 1 0 $a Parsons, Robert H., $e advisor
791 $a Ph.D.
792 $a 2004
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3122985