Temperature effects on synaptic transmission and neuronal function in the visual thalamus

Area of Science:

• Neuroscience
• Computational Neuroscience
• Physiology

Background:

• Neuronal function, including synaptic integration and spiking, is influenced by numerous properties like ion channels and neurotransmitter release.
• Temperature is a critical factor affecting neuronal physiology, with implications for both normal function and pathological states like fever-induced seizures.
• Understanding temperature's impact is crucial for interpreting experimental results and for comprehending conditions where body temperature deviates from physiological norms.

Purpose of the Study:

• To investigate the influence of temperature on synaptic properties and ion channel function in thalamocortical (TC) relay neurons.
• To elucidate how temperature changes affect the transformation of synaptic inputs into postsynaptic spiking in these neurons.
• To identify specific ion channel and synaptic mechanisms underlying temperature-dependent alterations in neuronal excitability.

Main Methods:

• Utilized acute brain slices of the dorsal lateral geniculate nucleus from rodents.
• Employed patch clamp techniques to record from TC relay neurons.
• Manipulated superfusate temperature during experiments involving retinal ganglion cell spike train stimulation.

Main Results:

• Warming the superfusate inhibited synaptically-driven spiking behavior in TC neurons.
• Increased presynaptic synaptic vesicle release probability and induced synaptic depression at higher temperatures.
• Observed alterations in passive and active membrane properties, including activation of an inwardly rectifying potassium current and modified voltage-dependence of Na+ and T-type Ca2+ currents.

Conclusions:

• Temperature exerts a significant influence on TC relay neuron function, impacting both synaptic transmission and intrinsic neuronal excitability.
• The observed changes in ion channel function and synaptic properties converge to modulate neuronal output, leading to overall inhibition of spiking when warmed.
• This study underscores the critical importance of meticulous temperature control in ex vivo electrophysiological experiments to ensure accurate and reproducible findings.