title: Oscillations in the embryonic chick olfactory bulb: initial expression and development revealed by optical imaging with a voltage-sensitive dye.
abstract: In a previous study, we applied a multiple-site optical recording technique with a voltage-sensitive dye to the embryonic chick olfactory system and showed that functional synaptic transmission in the olfactory bulb was expressed at embryonic 6-7-day stages. It is known that oscillations, i.e. stereotyped sinusoidal neural activity, appear in the olfactory system of various species. The focus of the present study is to determine whether the oscillation is also generated in the embryonic chick olfactory bulb and, if this is the case, when the oscillation appears and how its profiles change during embryogenesis. At the early stages of development (embryonic 6- to 8-day stages), postsynaptic response-related optical signals evoked by olfactory nerve stimulation exhibited a simple monophasic waveform that lasted for a few seconds. At embryonic 9-day stage, the optical signal became multi-phasic, and the oscillatory event was detected in some preparations. The oscillation was restricted to the distal half of the olfactory bulb. As development proceeded, the incidence and duration of the oscillation gradually increased, and the waveform became complicated. In some cases at embryonic 12-day stage, the oscillation lasted for nearly a minute. The frequency of the oscillation increased slightly with development, but it remained in the range of theta oscillation during the 9- to 12-day stages. We discuss the ontogenetic dynamics of the oscillation and the significance of this activity in the developing olfactory bulb.
authors.affiliation: Department of Health and Nutrition Sciences, Faculty of Human Health, Komazawa Women's University, Inagi-shi, Tokyo, 206-8511, Japan.
authors.forename: Katsushige
authors.initials: K
authors.lastname: Sato
authors.affiliation: Department of Neurosurgery, Faculty of Medicine, Tokyo Medical and Dental University Graduate School, Tokyo, Japan.
authors.forename: Shihori
authors.initials: S
authors.lastname: Hayashi
authors.affiliation: Department of Neurosurgery, Faculty of Medicine, Tokyo Medical and Dental University Graduate School, Tokyo, Japan.
authors.forename: Motoki
authors.initials: M
authors.lastname: Inaji
authors.affiliation: Department of Nutrition and Dietetics, College of Nutrition, Kanto Gakuin University, Kanazawa-ku, Yokohama, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Momose-Sato
mesh_terms: D000200:Action Potentials; D000818:Animals; D002642:Chick Embryo; D009830:Olfactory Bulb / Q000196:embryology / Q000502:physiology*; D056969:Voltage-Sensitive Dye Imaging
keywords: chick embryo; olfactory bulb; optical recording; oscillation; voltage-sensitive dye