title: Depolarization waves in the embryonic CNS triggered by multiple sensory inputs and spontaneous activity: optical imaging with a voltage-sensitive dye.
abstract: Previously, we discovered a novel type of depolarization wave in the embryonic chick brain by using a multiple-site optical recording technique with a fast voltage-sensitive dye. This depolarization wave traveled widely over almost all the region of the CNS. This profile has raised the possibility that the depolarization wave plays some global roles in development of the CNS, rather than contributing to a specific neuronal circuit formation. To obtain more information concerning this issue, in the present study, we examined whether the depolarization wave was triggered by various types of peripheral nerve inputs. Stimulation applied to the vagus, glossopharyngeal, cochlear and trigeminal nerves evoked widely spreading depolarization waves with similar spatiotemporal distribution patterns. The developmental sequence of wave expression was parallel to the development of the excitatory postsynaptic potentials in each sensory nucleus. The depolarization wave was accompanied by a Ca(2+)-wave, suggesting that not only electrical synchrony, but also large-scale Ca(2+)-transients may affect developmental processes in the embryonic brain. Furthermore, we found that the depolarization wave also occurred spontaneously. The waveform and distribution patterns of the spontaneous optical signals were similar to those of the cranial nerve-evoked depolarization wave. These results demonstrated that the depolarization wave in the embryonic chick brain is triggered by multiple sources of external and endogenous activity. This profile supports the idea that this depolarization wave may not serve as a simple regulator of specific neuronal circuit formation, but might play more global roles in CNS development.
authors.affiliation: Department of Physiology, Tokyo Medical and Dental University, Graduate School and Faculty of Medicine, Bunkyo-ku, Tokyo 113-8519, Japan. yoko.phy2@tmd.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Momose-Sato
authors.forename: H
authors.initials: H
authors.lastname: Mochida
authors.forename: S
authors.initials: S
authors.lastname: Sasaki
authors.forename: K
authors.initials: K
authors.lastname: Sato
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000166:cytology / Q000196:embryology* / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology; D002642:Chick Embryo; D003056:Cochlear Nerve / Q000166:cytology / Q000254:growth & development / Q000502:physiology; D003391:Cranial Nerves / Q000166:cytology* / Q000254:growth & development / Q000502:physiology; D004558:Electric Stimulation; D005930:Glossopharyngeal Nerve / Q000166:cytology / Q000254:growth & development / Q000502:physiology; D008564:Membrane Potentials / Q000502:physiology; D009434:Neural Pathways / Q000166:cytology / Q000254:growth & development / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology*; D055095:Optics and Photonics; D014276:Trigeminal Nerve / Q000166:cytology / Q000254:growth & development / Q000502:physiology; D014630:Vagus Nerve / Q000166:cytology / Q000254:growth & development / Q000502:physiology