The rhythmic neural circuits in cold-blooded animals function in variable temperatures because although their frequency is temperature-dependent, phase is temperature-independent.
“The neural circuits that produce behaviors such as walking, chewing, and
swimming must be both robust and flexible to changing internal and
environmental demands. How then do cold-blooded animals cope with
temperature fluctuations when the underlying processes that give rise to
circuit performance are themselves temperature-dependent? We exploit
the crab stomatogastric ganglion to understand the extent to which
circuit features are robust to temperature perturbations. We subjected
these circuits to temperature ranges they normally encounter in the
wild. Interestingly, while the frequency of activity in the network
increased 4-fold over these temperature ranges, the relative timing
between neurons in the network—termed phase relationships—remained
constant. To understand how temperature compensation of phase might
occur, we characterized the temperature dependence (Q10‘s) of synapses and membrane currents. We used computational models to show that the experimentally measured Q10‘s
can promote phase maintenance. We also showed that many model bursting
neurons fail to burst over the entire temperature range and that phase
maintenance is promoted by closely restricting the model neurons’ Q10‘s.
These results imply that although ion channel numbers can vary between
individuals, there may be strong evolutionary pressure that restricts
the temperature dependence of the processes that contribute to
temperature compensation of neuronal circuits.
“…We speculate that the strong temperature dependence of frequency and
temperature-independence of phase may not be unique to the pyloric
circuit of the stomatogastric nervous system and may be a useful
property to other animals, allowing them to cope with environmental
challenges in their natural setting.” (Tang et al. 2010:e1000469)
