# 6.021/Notes/2006-11-03

## 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.
• $\displaystyle{ \tau_m \approx 1-2 ms, \tau_n \approx 3-4 ms, \tau_h \approx 3-4 ms }$
• 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.