Optical survey of vagus nerve-related neuronal circuits in the embryonic rat brainstem

2019

IBRO Reports

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Highlights We applied voltage-sensitive dye recording to the embryonic mouse brainstem. We examined functiogenesis of the N.IX-related neural circuits. Synaptic function in the NTS was first expressed at E12. Synaptic function in the 2nd/higher-order sensory nuclei emerged at E12–13. Response areas in the NTS were different between the N.IX and the N.X.

Section: Discussionsupporting

confidence: 79%

Voltage-sensitive dye recording of glossopharyngeal nerve-related synaptic networks in the embryonic mouse brainstem

2019

IBRO Reports

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“…The spatial distribution patterns of the polysynaptic response identified in the present experiment were very similar to those reported in the rat embryo (Momose‐Sato et al ., ), but not those in the chick embryo (Sato et al ., ) (Fig. ).…”

Section: Discussionmentioning

confidence: 89%

Development of synaptic networks in the mouse vagal pathway revealed by optical mapping with a voltage‐sensitive dye

2016

Eur J of Neuroscience

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The central issue in developmental neuroscience is when and how neural synaptic networks are established and become functional within the central nervous system (CNS). Investigations of the neural network organization have been hampered because conventional electrophysiological means have some technical limitations. In this study, the multiple-site optical recording technique with a voltage-sensitive dye was employed to survey the developmental organization of the vagal system in the mouse embryo. Stimulation of the vagus nerve in E11-E14 mouse embryos elicited optical responses in areas corresponding to the vagal sensory and motor nuclei. Postsynaptic responses in the first-order sensory nucleus, the nucleus of the tractus solitarius (NTS), were identified from E11, suggesting that sensory information becomes transferred to the brain at this stage. In addition to the NTS, optical responses were identified in the rostral and contralateral brainstem regions, which corresponded to second/higher order nuclei of the vagus nerve including the parabrachial nucleus (PBN). Postsynaptic responses in the second/higher-order nuclei were detected from E12, suggesting that polysynaptic networks were functional at this stage. We discuss the results of our optical mapping, comparing them with previous findings obtained in the chick and rat embryos, and suggest some fundamental principles in the functional organization of synaptic networks in the embryonic brain.

“…In the embryonic rat brainstem, the optical recording method with a VSD has been applied to the trigeminal, glossopharyngeal, and vagal systems, and functional development of the related nuclei has been investigated (Momose‐Sato, Honda, Sasaki, & Sato, ; Momose‐Sato, Nakamori, Mullah, & Sato, ; Momose‐Sato, Nakamori, & Sato, ; Momose‐Sato, Sato, & Kamino, ; Sato et al., , ). In the present study, we applied this optical technique to embryonic rat N.VII‐brainstem preparations, and succeeded in revealing the functional organization of the facial motor system.…”

Section: Discussionmentioning

confidence: 99%

Optical analysis of functional development of the facial motor nucleus in the embryonic rat brainstem

2018

Eur J of Neuroscience

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Facial motor neurons of the rat embryo are first generated in rhombomere 4 and then migrate in the caudo-ventral direction. This migration forms a unique axonal trajectory called the genu, a loop of facial motor axons around the abducens nucleus. It is still unclear when and how this unique structure is functionally established during ontogenesis. Using voltage-sensitive dye (VSD) recording and the DiI staining method, we identified neural responses evoked by facial nerve (N.VII) stimulation and examined developmental processes of the facial motor nucleus in E12-E17 rat brainstems. We identified two types of fast spike-like signals; a long-duration signal, which corresponded to the action potential in the N.VII soma, and a short-duration signal, which reflected the action potential in the N.VII axons. The long-duration signal was detected as early as E13, suggesting that the N.VII motor neuron is already excitable at the beginning of cell migration. The response area of the long-duration signal extended caudally at E13-E14, and shifted in a ventral direction at E15. At E16-E17, the long-duration signal was concentrated in the caudo-ventral area, which was comparable to the location of the facial motor nucleus in the adult rat brainstem. These results demonstrate that developmental processes of cell migration and nuclear organization can be visualized and identified functionally with the VSD recording. We discuss the results by comparing functiogenesis and morphogenesis of the N.VII pathway.