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 if 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.
During breathing, the diaphragm and abdominal muscles contract out of phase. However, during other behaviors (including vomiting and postural adjustments) simultaneous increases in the activity of the diaphragm and abdominal muscles are required. 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 medullary reticular formation (MRF) influence diaphragm activity. The goal of the present study was to determine if neurons in these regions have collateralized projections to diaphragm motoneurons and the upper lumbar spinal cord, where abdominal motoneurons are located. 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 L1 spinal segment. A large fraction of the neurons in the MRF and VN (median of 75 and 91%, respectively) that were infected by rabies virus were dual‐labeled by FG. These data show that MRF and VN neurons have connectivity with both phrenic and abdominal motoneurons, and thus can simultaneously regulate the activity of both the diaphragm and abdominal musculature. Future studies should focus on the physiological role of these neurons in producing co‐contractions of inspiratory and expiratory muscles.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.