Date(s) - 02/15/2016
Title: Can Neural Activity Propagate by Endogenous Electrical Field?
It is widely accepted that synaptic transmissions and gap junctions are the major governing mechanisms for a signal traveling in the neural system. A group of neural waves, either physiological or pathological, share the same speed of ~0.1m/s without synaptic transmission or gap junctions, and this speed is not consistent with axonal conduction or ionic diffusion. Data will be presented to show that endogenous electric fields are sufficient to explain the propagation with in-silico and in-vitro experiments. Simulation results show that field effects alone can indeed mediate propagation across layers of neurons with speeds of 0.12 ± 0.09m/s with pathological kinetics, and 0.11±0.03m/s with physiological kinetics, both generating weak field amplitudes of ~2-6mV/mm. Further, the model predicts that propagation speed values are inversely proportional to the cell-to-cell distances, but do not significantly change with extracellular resistivity, membrane capacitance, or membrane resistance. In-vitro recordings in mice hippocampi produced similar speeds (0.10±0.03m/s) and field amplitudes (2.5-5mV/mm), and by applying a blocking field, the propagation speed was greatly reduced. Finally, osmolarity experiments confirmed the model’s prediction that cell-to-cell distance inversely affects propagation speed. These results indicate that despite their weak amplitude, electric fields can be responsible for neural activity propagation at around 0.1m/s. This phenomenon could be important to explain the slow propagation of epileptic activity and other physiological propagating waves at similar speeds.
Short CV: Dominique M. Durand is E.L. Linsedth Professor of Biomedical Engineering and Neurosciences and Director of the Neural Engineering Center at Case Western Reserve University in Cleveland, Ohio. He received an engineering degree from Ecole Nationale Superieure d’Electronique, Hydrolique, Informatique et Automatique de Toulouse, France in 1973. In 1974, he received an M.S. degree in Biomedical Engineering from Case Reserve University in Cleveland, Ohio, worked several years at the Addiction Research Foundation of Toronto, Canada and in 1982 received a Ph.D. in Electrical Engineering from the University of Toronto in the Institute of Biomedical Engineering. He received an NSF Young Investigator Presidential Award as well as the Diekhoff and Wittke awards for graduate and undergraduate teaching and the Mortar board top-prof awards at Case Western Reserve University. He is an IEEE Fellow and also Fellow of the American Institute for Medical and Biomedical Engineering and Fellow of the Institute of Physics. He serves on many editorial boards of peer-reviewed scientific journals, and he is the Editor-In-Chief and founding editor of the Journal of Neural Engineering. His research interests are in neural engineering and include computational neuroscience, neurophysiology, and control of epilepsy, non-linear dynamics of neural systems, neural prostheses and applied magnetic and electrical field interactions with neural tissue. He has obtained funding for his research from the National Science Foundation, the National Institutes of Health and private foundations. He has published over 140 articles, and he has consulted for many biotechnology companies and foundations.