Spontaneous depolarization waves of multiple origins in the embryonic rat CNS : Optical imaging with voltage-sensitive dyes.

点击翻译按钮获取中文摘要

During development, correlated neuronal activity plays an important role in the establishment of the central nervous system (CNS). We recently reported that in the embryonic rat CNS, a widely-propagating correlated neuronal activity, termed the depolarization wave, is evoked by various sensory nerve inputs. A remarkable feature of the depolarization wave is how it spread broadly through the brain and spinal cord. In the present study, we examined whether the depolarization wave occurs spontaneously in the embryonic rat CNS, and if so, where it originates. In E15-E16 rat embryos, spontaneous optical signals appeared in association with the rhythmic discharges of cranial motoneurons, and propagated through the brain and spinal cord with similar characteristics to the evoked depolarization wave. The spontaneous wave originated in multiple locations including two restricted regions located in the dorsomedial pons and rostral ventrolateral medulla as well as the media/caudal medulla and spinal cord. When the spinal cord was intact, the wave at E16 mainly originated in the lumbosacral region, although a wave associated with the oscillatory event was also generated in the cervical cord/caudal medulla. In preparations in which the spinal cord was transected, the contribution of the pons and medulla was more significant. These results show that the depolarization wave is triggered by the spontaneous activity of multiple neuronal populations which distribute widely from the pons to the lumbosacral cord. The network possibly behaves as a self-distributing system that maintains the incidence and complicated patterns of the correlated activity in the developing CNS.