# 6.021/Notes/2006-11-03

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## Hodgkin-Huxley

• Each factor can also be written as rates ${\displaystyle \alpha ,\beta }$
• ${\displaystyle x_{\infty }={\frac {\alpha _{x}}{\alpha _{x}+\beta _{x}}},\tau _{x}={\frac {1}{\alpha _{x}+\beta _{x}}}}$
• The effect of temperature is to multiple rates by ${\displaystyle K_{T}=3^{T_{c}-6.3}}$
• An increase in temperature decreases all 3 time constants but has no effect on the final values.
• At high temperature, no action potential is seen
• There's another time constant due to capacitance in membrance
• Changes in conductances have time delay before membrane potential changes
• ${\displaystyle \tau _{M}}$ (membrane "RC" time constant) is about 1-2 ms.
• ${\displaystyle \tau _{m}\approx 1-2ms,\tau _{n}\approx 3-4ms,\tau _{h}\approx 3-4ms}$
• increase in temperature causes the ${\displaystyle G_{K}}$ wave to catch up with the ${\displaystyle G_{Na}}$ wave
• As increase temperature, both approach ${\displaystyle \tau _{M}}$. If waves go at same speed, cannot have action potential.