Temperature-robust activity patterns arise from coordinated axonal Sodium channel properties

Area of Science:

• Neuroscience
• Computational Neuroscience
• Biophysics

Background:

• Action potentials are vital for neuronal communication, with precise timing essential for cognitive functions.
• Axons must faithfully transmit action potentials over long distances while maintaining timing, a challenge exacerbated by varying axonal properties and environmental changes.
• The impact of temperature fluctuations on the timing fidelity of diverse axons remains largely unexplored.

Purpose of the Study:

• To investigate whether ambient temperature changes alter action potential timing in different types of crustacean axons.
• To identify the mechanisms underlying temperature-robust timing in diverse neuronal projections.
• To determine if temperature-sensitive ion channel properties can support stable neuronal timing across distinct axon types.

Main Methods:

• Combined computational modeling, in vivo imaging, and electrophysiology in the motor circuit of Cancer borealis.
• Exposed axons from three distinct neuron types to a range of physiological temperatures.
• Analyzed action potential propagation and timing fidelity across different axonal morphologies.

Main Results:

• Despite significant axonal differences, temperature changes had moderate effects on action potential propagation, preserving timing over long distances.
• The study demonstrated temperature-robust timing across diverse neuronal types involved in the same functional task.
• Modeling revealed that coordinated temperature sensitivities of sodium channel activation gate time constant and maximum sodium conductance are key to maintaining timing.

Conclusions:

• Diverse axons can maintain temperature-robust action potential timing essential for neuronal communication.
• Specific coordination of temperature-sensitive ion channel properties, rather than insensitivity, supports stable neuronal timing.
• These findings highlight a conserved mechanism for neuronal timing robustness across different neuronal types and distances, even under varying temperatures.