Understanding the Breathing Circuit

 

    Breathing is an essential mechanism of life, a rhythm that sustains life and it is often unnoticed until we pause to truly feel it, mindful breathing. Breathing is automatically regulated to maintain homeostasis but can also adapt to changes in the body such as behavior and emotional changes ensuring it aligns with the body’s specific needs (Seattle Children’s Hospital, n.d). Breathing rhythm generation is controlled by the preBötzinger complex, a neural network located in the brainstem, and understanding the neural circuits in breathing could serve as a model to understand other neural circuits in the body.

    The research article, Facing the challenge of mammalian neural microcircuits: taking a few breaths may help, Dr. Jordan J. Skach and colleagues describe the complex mechanism underlying respiratory rhythm generation in mammals that is controlled by the preBötzinger Complex found in the brainstem. Despite decades of research, the breathing mechanism is still not well understood. Although breathing seems like a simple well-defined behavior, conventional rhythm generation models such as those involved in pacemakers, inhibition, or bursting are problematic and ignore consequential detail. Dr. Jordan J. Skach and colleagues argue that respiratory rhythm likely emerges from intricate and dynamic molecular, synaptic and neuronal interactions within a diverse neural microcircuit. This idea underlines the challenges in understanding neural control of mammalian behaviors and proposes that neural circuit governing breathing is inimitably accessible and could serve as a model for general strategies to understand other neural microcircuits.

    In the research article, PreBötzinger complex neurons drive respiratory modulation of blood pressure and heart rate, researchers examine how respiratory activity oscillates in phase with heart rate and blood pressure. The use of optogenetic inhibition and excitation as well as neuronal tracing in rats was used to demonstrate that the PreBötzinger complex neurons directly modulate cardiovascular activity. Inhibitory PreBötzinger complex neurons modulate parasympathetic activity which affects heart rate, and excitatory PreBötzinger complex neurons modulate sympathetic vasomotor neuron activity which affects blood pressure. This was found to generate heart rate and blood pressure oscillations in phase with respiration. Findings suggest that the PreBötzinger complex has a broader function in the regulation of these physiological processes. The study highlights the PreBötzinger complex role in cardiorespiratory interactions and its potential implications for cardiovascular diseases where respiratory synchrony of heart rate and blood pressure is disrupted.

    Both research studies highlight the PreBötzinger complex as a central neural hub for regulating physiological rhythms such as cardiovascular and breathing rhythms. Both studies explore the challenges of the PreBötzinger complex function and emphasize the complexity of the role it plays in respiratory rhythms and cardiovascular integration. These studies suggest that the PreBötzinger complex has is a complicated mechanism that could be further studied and serve as a model to understand other neural microcircuits, but when in doubt breathe in…breathe out.

 

Feldman, J. L., & Kam, K. (2014). Facing the challenge of mammalian neural microcircuits: Taking a few breaths may help. The Journal of Physiology, 593(1), 3–23. https://doi.org/10.1113/jphysiol.2014.277632

Menuet, C., Connelly, A. A., Bassi, J. K., Melo, M. R., Le, S., Kamar, J., Kumar, N. N., McDougall, S. J., McMullan, S., & Allen, A. M. (2020). PreBötzinger complex neurons drive respiratory modulation of blood pressure and heart rate. eLife, 9. https://doi.org/10.7554/elife.57288

Neural circuits, breathing, behavior and emotion - baertsch lab. Seattle Children’s Hospital. (n.d.). https://www.seattlechildrens.org/research/centers-programs/integrative-brain-research/our-labs/baertsch-lab/identifying-neural-circuits-breathing-emotion/