Cellular excitability and ns-pulsed electric fields: Potential involvement of lipid oxidation in the action potential activation

Recent studies showed that nanosecond pulsed electric fields (nsPEFs) can activate voltage-gated ion channels (VGICs) and trigger action potentials (APs) in excitable cells. Under physiological conditions, VGICs' activation takes place on time scales of the order 10-100 µs. These time scales are considerably longer than the applied pulse duration, thus activation of VGICs by nsPEFs remains puzzling and there is no clear consensus on the mechanisms involved. Here we propose that changes in local electrical properties of the cell membrane due to lipid oxidation might be implicated in AP activation. We first use MD simulations of model lipid bilayers with increasing concentration of primary and secondary lipid oxidation products and demonstrate that oxidation not only increases the bilayer conductance, but also the bilayer capacitance. Equipped with MD-based characterization of electrical properties of oxidized bilayers, we then resort to AP modelling at the cell level with Hodgkin-Huxley-type models. We confirm that a local change in membrane properties, particularly the increase in membrane conductance, due to formation of oxidized membrane lesions can be high enough to trigger an AP, even when no external stimulus is applied. However, excessive accumulation of oxidized lesions (or other conductive defects) can lead to altered cell excitability.

Towards dynamical network biomarkers in neuromodulation of episodic migraine

Computational methods have complemented experimental and clinical neurosciences and led to improvements in our understanding of the nervous systems in health and disease. In parallel, neuromodulation in form of electric and magnetic stimulation is gaining increasing acceptance in chronic and intractable diseases. In this paper, we firstly explore the relevant state of the art in fusion of both developments towards translational computational neuroscience. Then, we propose a strategy to employ the new theoretical concept of dynamical network biomarkers (DNB) in episodic manifestations of chronic disorders. In particular, as a first example, we introduce the use of computational models in migraine and illustrate on the basis of this example the potential of DNB as early-warning signals for neuromodulation in episodic migraine.