Department of Otolaryngology, University of Pittsburgh, Eye and Ear Institute, Pittsburgh, PA 15213, USA.
Exp Brain Res. 2010 May;203(1):205-11. doi: 10.1007/s00221-010-2197-3. Epub 2010 Feb 26.
During breathing, the diaphragm and abdominal muscles contract out of phase. However, during other behaviors (including vomiting, postural adjustments, and locomotion) simultaneous contractions are required of the diaphragm and other muscle groups including abdominal muscles. Recent studies in cats using transneuronal tracing techniques showed that in addition to neurons in the respiratory groups, cells in the inferior and lateral vestibular nuclei (VN) and medial pontomedullary reticular formation (MRF) influence diaphragm activity. The goal of the present study was to determine whether neurons in these regions have collateralized projections to both diaphragm motoneurons and the lumbar spinal cord. For this purpose, the transneuronal tracer rabies virus was injected into the diaphragm, and the monosynaptic retrograde tracer Fluoro-Gold (FG) was injected into the Th13-L1 spinal segments. A large fraction of MRF and VN neurons (median of 72 and 91%, respectively) that were infected by rabies virus were dual-labeled by FG. These data show that many MRF and VN neurons that influence diaphragm activity also have a projection to the lumbar spinal cord and thus likely are involved in coordinating behaviors that require synchronized contractions of the diaphragm and other muscle groups.
在呼吸过程中，横膈膜和腹部肌肉不协调收缩。然而，在其他行为（包括呕吐、姿势调整和运动）中，需要同时收缩横膈膜和包括腹部肌肉在内的其他肌肉群。最近猫的研究使用跨神经元追踪技术表明，除了呼吸组中的神经元外，前庭下核（VN）和中桥脑网状结构（MRF）中的细胞也会影响横膈膜的活动。本研究的目的是确定这些区域的神经元是否有分支投射到横膈膜运动神经元和腰椎脊髓。为此，将跨神经元示踪剂狂犬病毒注射到横膈膜中，并将单突触逆行示踪剂 Fluoro-Gold（FG）注射到 Th13-L1 脊髓节段。被狂犬病毒感染的 MRF 和 VN 神经元的很大一部分（分别为中位数的 72%和 91%）被 FG 双重标记。这些数据表明，许多影响横膈膜活动的 MRF 和 VN 神经元也有向腰椎脊髓的投射，因此可能参与协调需要横膈膜和其他肌肉群同步收缩的行为。
