Robust network oscillations during mammalian respiratory rhythm generation driven by synaptic dynamics.

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• The preBötzinger complex (preBötC) is a mammalian brainstem network crucial for respiratory rhythm generation.
• The precise mechanisms by which synaptic dynamics create synchronous oscillations and rhythmic activity in the preBötC remain unclear.
• Neuronal networks exhibit bursting and silent periods, essential for vital functions like breathing.

Purpose of the Study:

• To investigate how synaptic dynamics, specifically short-term facilitation (SF) and short-term depression (SD), contribute to synchronous oscillations in neuronal networks.
• To model the preBötzinger complex (preBötC) to understand the generation of respiratory rhythms.
• To elucidate the role of synaptic plasticity in generating both rhythmic activity and network lability.

Main Methods:

• Computational modeling of a randomly connected neuronal network incorporating short-term synaptic facilitation (SF) and depression (SD).
• Validation of the computational model against various experimental conditions mimicking preBötC activity.
• Electrophysiological recordings to assess SF/SD at preBötC synapses and their influence on rhythmic activity.

Main Results:

• Synaptic fluctuations in the model can initiate population activities via recurrent excitation.
• A two-step short-term depression (SD) process synchronizes network activity into bursts and creates a refractory period for silence.
• Electrophysiological data confirmed SF/SD at preBötC synapses on relevant timescales for rhythmic activity.

Conclusions:

• Nondeterministic neuronal spiking and dynamic synaptic strengths are sufficient to produce regular, respiratory-like rhythmic network activity.
• Synaptic dynamics play a critical role in the generation of breathing rhythms and network lability.
• The findings suggest a generalizable mechanism for rhythmic motor control in mammals.