This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Block, G. D. Articles by Lusska, A. E. Search for Related Content PubMed PubMed Citation Articles by Block, G. D. Articles by Lusska, A. E. Social Bookmarking                         What's this?

Cellular Analysis of Ocular Circadian Pacemaker Coupling in Bulla: Role of Efferent Impulses in Phase Shifting

Department of Biology, Gilmer Hall, University of Virginia, Charlottesville, Virginia 22901

Michael H. Roberts

Department of Biology, Gilmer Hall, University of Virginia, Charlottesville, Virginia 22901

Amy E. Lusska

Department of Biology, Gilmer Hall, University of Virginia, Charlottesville, Virginia 22901

The eyes of Bulla gouldiana, a marine snail, contain circadian oscillators that are coupled to each other. Obvious candidates for the coupling signals are the optic nerve compound action potentials (CAPs) that express the circadian rhythm and lead to efferent impulses in the contralateral optic nerve. In the present experiments, the role of the CAPs as coupling signals was evaluated. We found that, following desynchronization of the two ocular oscillators by phase-delaying one eye with manganese, subsequent phase shifts in the initially unshifted ocular rhythm only occurred during the time that efferent optic nerve signals were present. In addition, in the absence of ocular desynchrony, phase shifts of the ocular rhythm could still be effected by activation of the efferent pathway.

The influence of efferent impulses on identified retinal cells was also evaluated. No effect of efferent signals on receptor layer cells was detected, while it was found that efferent impulses generated depolarizations in basal retinal neurons (BRNs), the putative circadian oscillator cells. Depolarization of the BRNs has been shown previously to be involved in the light entrainment pathway. Depolarization appears to be similarly involved in the coupling pathway, since membrane depolarizations that mimicked the efferent-induced postsynaptic potentials likewise generated phase shifts of the ocular rhythm.

Journal of Biological Rhythms, Vol. 1, No. 3, 199-217 (1986)
DOI: 10.1177/074873048600100303


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				T. L. Page, G. T. Wassmer, J. Fletcher, and G. D. Block Aftereffects of Entrainment on the Period of the Pacemaker in the Eye of the Mollusk Bulla gouldiana J Biol Rhythms, June 1, 1997; 12(3): 218 - 225. [Abstract] [PDF]

				T. L. Page and K. G. Nalovic Properties of Mutual Coupling between the Two Circadian Pacemakers in the Eyes of the Mollusc Bulla gouldiana J Biol Rhythms, October 1, 1992; 7(3): 213 - 226. [Abstract] [PDF]

				M. E. Geusz and G. D. Block The Retinal Cells Generating the Circadian Small Spikes in the Bulla Optic Nerve J Biol Rhythms, October 1, 1992; 7(3): 255 - 268. [Abstract] [PDF]