Neurons in poikilotherms must operate over the animal's natural temperature range if they are to survive. The effects of temperature on various cellular processes can vary dramatically, which suggests that it may be difficult to design a circuit that behaves consistently over a temperature range. Previous work in the crab Cancer borealis (Tang et al., 2010, 2012) showed that the pyloric rhythm of the stomatogastric ganglion (STG) maintains its bursting duty cycle and phase relationships over a temperature range of 7 to 23 °C. Rinberg et al., 2013 also observed this phase invariance over a temperature range in the three cell pyloric pacemaker kernel.
To explore the effects of temperature on this system, we implemented a computational model of the STG pacemaker kernel (Soto-Treviño et al., 2005), that simulates two electrically coupled cells and includes temperature dependences, represented as Q10's. Separate Q10's were assigned for maximal conductance, rate of activation and inactivation. We also assigned a Q10 for the buffering rate of intracellular Ca2+. All Q10's were selected randomly from 1 to 4, except the maximal conductance Q10's that were set to 1.6. Maximal conductance values at the reference temperature of 11 °C were initially set to the values selected by Soto-Treviño et al., 2005. Each model was run over a range of 7 to 23 °C.
While some Q10 values, such as those for mKCa, mKd and Ca2+ buffering are critical for appropriate temperature scaling, the system is only moderately sensitive to others such as hNa, CaT and CaS and largely insensitive to Q10 values for slower conductances such as A, Nap, IMI and leak.
Overall, we find that robust neuronal behavior can be achieved over a temperature range within a subset of Q10-space. Within our model, certain Q10's are tightly constrained while others can be chosen over a relatively wide range. This provides insight into the relative contribution of different ionic conductances to high-level neuronal dynamics.
|Commitee:||Epstein, Irving, Fee, Michale, Garrity, Paul, Miller, Paul|
|School Location:||United States -- Massachusetts|
|Source:||DAI-B 75/01(E), Dissertation Abstracts International|
|Keywords:||Ion channels, Phase maintenance, Pyloric rhythm, Stomatogastric ganglion, Temperature scaling|
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