Action-potential-encoded second-harmonic generation as an ultrafast local probe for nonintrusive membrane diagnostics

The Hodgkin-Huxley treatment of the dynamics of a nerve impulse on a cell membrane is combined with a phenomenological description of molecular hyperpolarizabilities to develop a closed-form model of an action-potential-sensitive second-harmonic response of membrane-bound chromophores. This model is employed to understand the key properties of the map between the action potential and modulation of the second harmonic from a cell membrane stained with hyperpolarizable chromophore molecules.