Response to multiplicative noise: The cross-spectrum of membrane voltage fluctuation and voltage-independent conductance noise

Abstract

We reveal that the correlation of voltage fluctuation and voltage-independent conductance noise, rather than the magnitude of the latter, explains most of the former. Being the response function in the spectral domain, the cross-spectrum has an order-three scaling law originating in the imaginary part, and it can be divided into three phases: left the real part dominant phase; right the imaginary part dominant phase; and center the transition phase. Since the coherence in the left phase has a greater decay rate than that in the right phase, an additional peak appears in the transition phase. All of these results imply that the effects of conductance noise, being multiplicative, cannot be characterized by the concept of impedance—which is adopted from the field of equilibrium thermodynamics.