QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

The Journal of Neuroscience, March 28, 2007, 27(13):3375-3382; doi:10.1523/JNEUROSCI.5496-06.2007

This Article Full Text Full Text (PDF) Submit an eLetter Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Related articles in J. Neurosci. Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Vidal, L. Articles by Morin, L. P. Search for Related Content PubMed PubMed Citation Articles by Vidal, L. Articles by Morin, L. P.

 Previous Article  |  Next Article 

Behavioral/Systems/Cognitive
Absence of Normal Photic Integration in the Circadian Visual System: Response to Millisecond Light Flashes

Luis Vidal¹ and Lawrence P. Morin^1,2

¹Department of Psychiatry and ²Program in Neuroscience, Stony Brook University, Stony Brook, New York 11794

Correspondence should be addressed to Dr. Lawrence P. Morin, Department of Psychiatry, Health Science Center, Stony Brook University, Stony Brook, NY 11794-8101. Email: lawrence.morin{at}stonybrook.edu

Light is the most prominent synchronizing stimulus for circadian rhythms. The circadian visual system responds in accordance with the energy content of photic stimuli longer than a few seconds. Here, as few as three flashes (2 ms each delivered to hamsters over 5 or 60 min at circadian time 19) elicited large phase advances. Ten or more flashes were required to induce FOS protein in the suprachiasmatic nucleus (SCN), and such induction occurred throughout the entire SCN, as well as outside the nucleus. High-density flash stimulation (0.5 s interflash interval) was ineffective, but response increased as the interval increased up to 4 s. In an irradiance response test, phase shifts appeared to be all-or-none with threshold irradiance between 140 and 1070 µW/cm², implying lack of stimulus energy summation. Nevertheless, an irradiance ineffective when delivered as 10 flashes induced phase shifts when given as100 flashes, but the response was substantially smaller than elicited by 10 flashes, each with 1 log unit more irradiance. The results also show reduced sensitivity of flash-induced FOS response in the intergeniculate leaflet compared with the SCN, contrary to studies using longer light stimuli. Masking was robust and prolonged in response to 10 flashes. The data demonstrate that the circadian visual system responds markedly to brief, intense light stimuli without normal photic integration. This may involve a second input pathway different from that mediating the effects of longer, dimmer photic stimuli.

Key words: suprachiasmatic; intergeniculate; pregeniculate; retina; photoreceptor; retinohypothalamic tract

---

Received Dec. 19, 2006; revised Jan. 29, 2007; accepted Feb. 16, 2007.

Correspondence should be addressed to Dr. Lawrence P. Morin, Department of Psychiatry, Health Science Center, Stony Brook University, Stony Brook, NY 11794-8101. Email: lawrence.morin{at}stonybrook.edu

Related articles in J. Neurosci.:

This Week in The Journal

J. Neurosci. 2007 27: i. [Full Text]  

This article has been cited by other articles:

				L.P. Morin and K.M. Studholme Millisecond Light Pulses Make Mice Stop Running, then Display Prolonged Sleep-Like Behavior in the Absence of Light J Biol Rhythms, December 1, 2009; 24(6): 497 - 508. [Abstract] [PDF]

				R. A. Hut, M. Oklejewicz, C. Rieux, and H. M. Cooper Photic Sensitivity Ranges of Hamster Pupillary and Circadian Phase Responses Do Not Overlap J Biol Rhythms, February 1, 2008; 23(1): 37 - 48. [Abstract] [PDF]

				M. Comas, D.G.M. Beersma, K. Spoelstra, and S. Daan Circadian Response Reduction in Light and Response Restoration in Darkness: A "Skeleton" Light Pulse PRC Study in Mice (Mus musculus) J Biol Rhythms, October 1, 2007; 22(5): 432 - 444. [Abstract] [PDF]

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help