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Determination of the retinal circuit...

Altimus, Cara M.

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Determination of the retinal circuitry responsible for light modulation of physiological and cognitive behaviors in mice.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Determination of the retinal circuitry responsible for light modulation of physiological and cognitive behaviors in mice./
作者:	Altimus, Cara M.
面頁冊數:	166 p.
附註:	Source: Dissertation Abstracts International, Volume: 72-03, Section: B, page: 1303.
Contained By:	Dissertation Abstracts International72-03B.
標題:	Neurobiology. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3440673
ISBN:	9781124423463

Determination of the retinal circuitry responsible for light modulation of physiological and cognitive behaviors in mice.
Altimus, Cara M.

Determination of the retinal circuitry responsible for light modulation of physiological and cognitive behaviors in mice. - 166 p.

Source: Dissertation Abstracts International, Volume: 72-03, Section: B, page: 1303.

Thesis (Ph.D.)--The Johns Hopkins University, 2010.

This item is not available from ProQuest Dissertations & Theses.

Circadian rhythms allow the daily coordination of many physiological cycles such as alertness, hormone regulation, and metabolism. To be physiologically relevant, these rhythms, which rarely have an endogenous 24-hour cycle, must be adjusted and aligned to the solar day's exact 24 hour period by sensing changes in irradiance during the day/night cycle. In mammals, rods, cones and melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) account for all light input from the retina to the brain to influence these light-dependent physiological functions. My thesis research determined the individual contribution of rods and cones and ipRGCs to circadian photoentrainment and the retinal circuitry necessary to transmit this light information to the brain. Initially, we found that the rod and cone signals require the ipRGCs to reach the brain regions that control circadian rhythms, acute light responses and pupillary light reflex. Using several genetic mouse lines, I revealed that the sensitivity of circadian photoentrainment is much higher than previously appreciated and is mediated by rods at low light intensities (cones and ipRGCs are not sensitive to these light levels). Surprisingly, even though rods are unable to contribute to image formation at high light intensity due to saturation, the saturated state is sufficient to signal the presence of high light intensity for photoentrainment. To determine the circuitry of rod signaling to the brain, I used animals that disrupt rod signaling through cones cells, a circuit used for rod signaling only at high light intensities. These animals showed an unforeseen outcome, namely animals photoentrain at low but not high light levels. These results have allowed quantification the photoreceptor contributions to photoentrainment and the circuitry necessary to transmit this information with light intensity resolution. To determine how light acutely affects physiological functions, I measured sleep and core body temperature changes in response to a three hour light pulse. For acute changes, I found that melanopsin was necessary and sufficient to drive the response; however, the electrical state of the outer retina may modulate the melanopsin light response. Finally I found that light environment affects cognitive functions, namely, learning and mood, in mice. Using mice that lack ipRGCs, we found that the light information is transmitted to the brain via ipRGCs. Overall our results demonstrate that the retinal photoreceptors display heterologous control over behaviors since photoentrainment, acute light responses and pupillary light constriction each show a distinct pattern of retinal inputs.

ISBN: 9781124423463Subjects--Topical Terms:

588707
Neurobiology.

Determination of the retinal circuitry responsible for light modulation of physiological and cognitive behaviors in mice.
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