On the theory of ion transport across the nerve membrane. IV. Noise from the open-close kinetics of K + channels

The theoretical power density spectrum G(f) of fluctuations in the steady-state squid axon K(+) current in the 10(3) Hz region has been derived assuming that these are fluctuations in the number of open K(+) channels in the Hodgkin-Huxley (HH) model. Various modifications of the HH model were also studied. The results were negative in all cases when compared with experiment. This confirms the generally held view that the observed G(f) approximately 1/f is associated primarily with K(+) current through open K(+) channels and not with the open-close kinetics of these channels.