Control of cardiac function and noise from a decaying power spectrum

Area of Science:

• Neuroscience
• Physiology
• Computational Biology

Background:

• Cardiac afferent neurons are crucial for feedback control of cardiac function.
• Understanding how these neurons process neural input is key to understanding cardiac output regulation.
• The role of noise in neural control of cardiac output remains debated.

Purpose of the Study:

• To investigate the extent to which neural control of cardiac output exploits noise.
• To model cardiac afferent neurons and their response to noisy inputs.
• To elucidate the mechanisms by which sensory neurons process noisy inputs to generate action potentials.

Main Methods:

• Analysis of in situ cardiac afferent activity.
• Modeling cardiac afferent neurons using Hodgkin-Huxley equations with red noise input.
• Derivation of a variable barrier competition model.
• Analysis of ion channel function in input signal processing.

Main Results:

• Cardiac afferent neurons exhibit independent, exponentially distributed interspike intervals.
• Ion channels perform input "whitening" by differentiating signals, enhancing high-frequency components.
• Spiking occurs when whitened inputs, averaged over a specific timescale, cross a threshold barrier.
• Input whitening helps differentiate low-frequency control signals from red noise.

Conclusions:

• Neural control of cardiac output appears to leverage noise.
• Ion channels play a critical role in transforming noisy sensory inputs into reliable neural signals.
• The variable barrier competition model provides a framework for understanding spike generation in response to noisy stimuli.