Breathing is composed of multiple, distinct behaviors that are bidirectionally regulated through autonomic and voluntary mechanisms. One behavioral component is the sigh, which serves distinct physiological and psychological roles. In two accompanying reviews we will discuss these roles. The present review focuses on the physiological function, where sighs play a critical role in controlling lung compliance by preventing the collapse of alveoli. Implicated in the generation of sighs and normal breathing is the preBötzinger Complex, a rhythmogenic network in the medulla. Although sighs and normal inspiration are generated within the same network, they show distinct temporal characteristics. While sighs occur every few minutes, normal breathing is generated in the range of seconds. Both are differentiated by distinct modulatory and synaptic mechanisms, and recent evidence indicates that these mechanisms are regulated by inputs from different regions of the brain. An important modulator of sighs is hypoxia, implicating sighs in the arousal response.
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http://dx.doi.org/10.1016/j.biopsycho.2022.108313 | DOI Listing |
Front Physiol
July 2024
Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States.
Introduction: Sex-specific patterns in respiratory conditions, such as asthma, COPD, cystic fibrosis, obstructive sleep apnea, and idiopathic pulmonary fibrosis, have been previously documented. Animal models of acute lung injury (ALI) have offered insights into sex differences, with male mice exhibiting distinct lung edema and vascular leakage compared to female mice. Our lab has provided evidence that the chemoreflex is sensitized in male rats during the recovery from bleomycin-induced ALI, but whether sex-based chemoreflex changes occur post-ALI is not known.
View Article and Find Full Text PDFBMC Pulm Med
July 2024
Department of Biology, University of British Columbia - Okanagan Campus, 3187 University Way, ASC366, Kelowna, BC, V1V1V7, Canada.
The lung is a highly mechanical organ as it is exposed to approximately 10 strain cycles, (where strain is the length change of tissue structure per unit initial length), with an approximately 4% amplitude change during quiet tidal breathing or 10 strain cycles at a 25% amplitude during heavy exercises, sighs, and deep inspirations. These mechanical indices have been reported to become aberrant in lung diseases such as acute respiratory distress syndrome (ARDS), pulmonary hypertension, bronchopulmonary dysplasia (BPD), idiopathic pulmonary fibrosis (IPF), and asthma. Through recent innovations, various in vitro systems/bioreactors used to mimic the lung's mechanical strain have been developed.
View Article and Find Full Text PDFbioRxiv
November 2024
Department of Neurobiology, DGSOM, UCLA, Los Angeles, California 90095-1763, USA.
We explored neural mechanisms underlying sighing. Photostimulation of parafacial (pF) neuromedin B (NMB) or gastrin releasing peptide (GRP), or preBötzinger Complex (preBötC) NMBR or GRPR neurons elicited ectopic sighs with latency inversely related to time from preceding endogenous sigh. Of particular note, ectopic sighs could be produced without involvement of these peptides or their receptors in preBötC.
View Article and Find Full Text PDFPhysiol Rep
March 2024
Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA.
Cervical spinal cord injury impacts ventilatory and non-ventilatory functions of the diaphragm muscle (DIAm) and contributes to clinical morbidity and mortality in the afflicted population. Periodically, integrated brainstem neural circuit activity drives the DIAm to generate a markedly augmented effort or sigh-which plays an important role in preventing atelectasis and thus maintaining lung function. Across species, the general pattern of DIAm efforts during a normal sigh is variable in amplitude and the extent of post-sigh "apnea" (i.
View Article and Find Full Text PDFJ Physiol
March 2024
Applied Science and Neuroscience, William & Mary, Williamsburg, VA, USA.
Breathing behaviour involves the generation of normal breaths (eupnoea) on a timescale of seconds and sigh breaths on the order of minutes. Both rhythms emerge in tandem from a single brainstem site, but whether and how a single cell population can generate two disparate rhythms remains unclear. We posit that recurrent synaptic excitation in concert with synaptic depression and cellular refractoriness gives rise to the eupnoea rhythm, whereas an intracellular calcium oscillation that is slower by orders of magnitude gives rise to the sigh rhythm.
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