Investigating the neural basis of multiphasic respiratory rhythm generation in the American Bullfrog
Date
2019-04-05
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Abstract
We breathe from the day we are born to the day we die; admittedly a cliché, but true nonetheless. Breathing is in fact so vital that it has historically been associated with a mythical life force; the very term ‘spirit’ is derived from the Latin word for a breath – ‘spiritus’ (Vanhove, 2008). This breathing ‘force’, as ancient medical practitioners serendipitously guessed, underscores nearly all of the physiological functions of the body. From something as (relatively) simple as oxygenating the blood to the control of something as elusive as one's mood and general health – all appears to be rooted in breathing. The centuries-old curiosity to decipher this rhythmic activity is, therefore, understandable. Thankfully, we have come a long way from describing breathing as a force. The mechanism of breathing has been thoroughly investigated, and over the last century of effort, we have discovered the neural underpinnings of the breath, but I suspect our work in deciphering breathing has just begun – the neural controller of breathing in vertebrates is still unresolved. My efforts, through this thesis, attempt to add to this growing body of knowledge. I utilized the central nervous system of the American Bullfrog (Rana catesbeiana) because it is arguably one of the champion organisms to study the neural control of breathing (Krogh's principle). In very general terms, I first confirm that the neural controller of breathing in bullfrogs is comprised of two independent respiratory oscillators (rhythm generating components) which couple over the course of metamorphosis. Second, I demonstrate that the bullfrog brain-stem hosts a third, previously undiscovered, respiratory oscillator. Finally, I show that the necessity of discrete respiratory oscillators can only be demonstrated under some conditions indicating that oscillators are labile and state-dependent entities.
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rhythm generation, central pattern generators, oscillators, breathing, ventilation, neural control of breathing, brainstem, amphibians, rana catesbeiana
Citation
Baghdadwala, M. I. (2019). Investigating the neural basis of multiphasic respiratory rhythm generation in the American Bullfrog (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.