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Interspike interval dependency from arterial chemoreceptors
Journal of Applied Physiology (Bethesda, Md. : 1985)
|November 1, 1985
Summary
Carotid body impulses are not random. Analysis reveals a negative feedback system within the carotid body, limiting variations in firing frequency for chemoreceptor afferents.
Area of Science:
- Neuroscience
- Physiology
- Respiratory Control
Background:
- The carotid body is a key chemoreceptor organ sensing blood oxygen and carbon dioxide levels.
- Its impulse generation has been modeled as a Poisson-type random process.
Purpose of the Study:
- To validate the Poisson-type random process characterization of the carotid body impulse generator.
- To investigate interspike interval dependency in sinus nerve spike trains from chemoreceptive afferents.
Main Methods:
- Recorded impulse trains from 15 single chemoreceptive afferents in vivo under hypoxic-hypercapnic conditions.
- Analyzed approximately 1,000 consecutive interspike intervals per fiber for serial dependence.
- Compared original spike trains with shuffled control series lacking serial dependence.
Main Results:
- Original spike trains exhibited significantly negative first-order serial correlation coefficients.
- Joint interval distributions of original trains showed less variability than shuffled controls.
- These findings indicate non-random firing patterns in chemoreceptor afferents.
Conclusions:
- The carotid body impulse generator does not operate as a simple Poisson-type random process.
- The observed interspike interval dependency suggests an intrinsic negative feedback mechanism.
- This feedback system likely regulates and limits variations in the mean firing frequency of chemoreceptors.