Volume 13 Supplement 1
Temperature-fastened sodium inactivation accounts for energy efficient cortical action potentials in mammalian brains
© Yu; licensee BioMed Central Ltd. 2012
Published: 16 July 2012
Recent experimental evidencs showed that action potential (AP) generation in mammalian, versus invertebrate, axons is remarkably energy efficient . Here we perform both computational (based on both traditional Hodgkin-Huxley model  and a cortical axon model  whose parameters are modified from experimental data) and experimental studies. Each supports that temperature is a major factor which directly modulates the level of energy cost of APs. Temperature increase results in a remarkable decrease in time constant of sodium channel closing and an increase in inactivation level of Na+ channel due to the Q10 effect (which quantifies the temperature dependent rate of biochemical reactions). This results in a marked reduction in overlap of the inward Na+, and outward K+ currents. As a consequence, the Na+ entry ratio gradually reaches to 1 (the theoretical optimal level, which requires only minimal Na+ charge for generating an AP) as temperature rises. Moreover, we also notice a remarkable exponential increase in firing rate and an exponential decrease in spike duration by both experimental and model studies. The total energy charge in response to a signal reaches a global minimum when temperature is around 37-42 oC. This suggests that warm body temperatures may help the mammalian brain to operate with minimal energy cost.
- Alle H, Roth A, Geiger JR: Energy-efficient action potentials in hippocampal mossy fibers. Science. 2009, 325: 1405-1408. 10.1126/science.1174331.View ArticlePubMedGoogle Scholar
- Hodgkin AL, Huxley AF: A quantitative description of membrane current and its application to conduction and excitation in nerve. J Physiol. 1952, 117: 500-44.PubMed CentralView ArticlePubMedGoogle Scholar
- Yu Y, Shu Y, McCormick DA: Cortical action potential backpropagation explains spike threshold variability and rapid-onset kinetics. J Neurosci. 2008, 28 (29): 7260-7272. 10.1523/JNEUROSCI.1613-08.2008.PubMed CentralView ArticlePubMedGoogle Scholar
- Attwell D, Laughlin SB: An energy budget for signaling in the grey matter of the brain. J Cereb Blood Flow Metab. 2001, 21 (10): 1133-1145.View ArticlePubMedGoogle Scholar
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