Bötzinger Complex
Published: Jul 16, 2023
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Updated: Aug 2, 2023
Written by Oseh Mathias
Founder, SpeechFit
The Bötzinger Complex (BötC) is a region of the brainstem located in the rostral ventrolateral medulla[1] which is near, and functionally related to, the pre-Bötzinger complex. Its primary role is to initiate expiration.
Both the BötC and the pre-BötC were identified through detailed mapping studies of neuronal discharge patterns across the ventrolateral medulla during different phases of the respiratory cycle.
The BötC contains both expiratory and inspiratory neurons but is most famous for its role in the control of expiration[5]. While expiration is a passive process during restful breathing, it becomes an active process during heavy breathing, as during exercise[6]. It is believed that the BötC is essential in controlling this active expiration[7].
When activated, the BötC sends inhibitory signals to the pre-BötC, inhibiting inspiration and initiating expiration[8]. The expiratory neurons within the BötC fire in synchrony with active expiration and help regulate the transition from inspiration to expiration[9].
The brainstem, where the Botzinger complex resides, contains several neuronal networks, including the central chemoreceptors that sense changes in blood chemistry, such as levels of oxygen, carbon dioxide, and pH. The BötC, along with the pre-BötC, is thought to play a significant role in respiratory adjustments to physiological challenges, such as hypercapnia (elevated CO2 levels) and hypoxia (low oxygen levels), helping to maintain homeostasis in response to varying metabolic demands[10].
Author
Oseh Mathias
SpeechFit Founder
Oseh is passionate about improving health and wellbeing outcomes for neurodiverse people and healthcare providers alike.
References
Smith, J.C., Ellenberger, H.H., Ballanyi, K., Richter, D.W. & Feldman, J.L. (1991). Pre-Bötzinger complex: A brainstem region that may generate respiratory rhythm in mammals. Science, 254, 726-729.
Richter, D.W. & Smith, J.C. (2014). Respiratory rhythm generation in vivo. Physiology, 29, 58-71.
What-When-How. (n.d.). Brainstem Areas Regulating Respiratory Function, Respiratory Neuronal Groups [Image]. In The Autonomic Nervous System (Integrative Systems) Part 6. Retrieved July 20, 2023, from http://what-when-how.com/neuroscience/the-autonomic-nervous-system-integrative-systems-part-6/
Appenzeller, O., & Coon, E. A. (2022). Brainstem areas involved in the control of respiration [Image]. In Introduction to Basic Aspects of the Autonomic Nervous System (6th ed.).
Janczewski, W.A. & Feldman, J.L. (2006). Distinct rhythm generators for inspiration and expiration in the juvenile rat. Journal of Physiology, 570, 407-420.
Ezure, K. & Tanaka, I. (2004). Distribution and medullary projection of respiratory neurons in the dorsolateral pons of the rat. Neuroscience, 127, 101-114.
Abdala, A.P., Rybak, I.A., Smith, J.C. & Paton, J.F. (2009). Abdominal expiratory activity in the rat brainstem–spinal cord in situ: patterns, origins and implications for respiratory rhythm generation. Journal of Physiology, 587, 3539-3559.
Onimaru, H., Ikeda, K. & Kawakami, K. (2008). CO2-sensitive preinspiratory neurons of the parafacial respiratory group express Phox2b in the neonatal rat. Journal of Neuroscience, 28, 12845-12850.
Pagliardini, S., Janczewski, W.A., Tan, W., Dickson, C.T., Deisseroth, K. & Feldman, J.L. (2011). Active expiration induced by excitation of ventral medulla in adult anesthetized rats. Journal of Neuroscience, 31, 2895-2905.
Guyenet, P.G. & Bayliss, D.A. (2015). Neural control of breathing and CO2 homeostasis. Neuron, 87, 946-961.