Inspiratory rhythm generation is stabilized by I_h

Area of Science:

• Neuroscience
• Respiratory Physiology
• Computational Biology

Background:

• The pre-Bötzinger complex (preBötC) generates rhythmic breathing.
• Cellular properties must balance flexibility and stability for breathing control.
• Opioid exposure and reduced synaptic drive can disrupt respiratory rhythm.

Purpose of the Study:

• To investigate the role of the hyperpolarization-activated, nonselective cation current (Ih) in stabilizing preBötC activity.
• To determine how Ih loss affects respiratory rhythm under perturbed conditions.
• To understand Ih's contribution to tonic spiking in preBötC neurons.

Main Methods:

• In silico modeling of the preBötC network.
• In vitro electrophysiological recordings.
• In vivo respiratory monitoring in animal models.

Main Results:

• Loss of Ih minimally affected baseline breathing frequency but destabilized rhythmogenesis, producing burstlets.
• Ih loss increased susceptibility to opioid-induced respiratory depression and weakened synaptic interactions.
• Ih is crucial for maintaining tonic spiking in preBötC neurons, which are both excitatory and inhibitory.

Conclusions:

• The Ih current is essential for stabilizing inspiratory rhythmogenesis in the preBötC.
• Ih promotes tonic spiking and protects breathing against perturbations like opioid exposure.
• Ih expands the dynamic range of rhythmogenesis and prevents unsynchronized network activity.