title: Ultrafast traveling wave dominates the electric organ discharge of Apteronotus leptorhynchus: an inverse modelling study.
abstract: Identifying and understanding the current sources that give rise to bioelectric fields is a fundamental problem in the biological sciences. It is very difficult, for example, to attribute the time-varying features of an electroencephalogram recorded from the head surface to the neural activity of specific brain areas; model systems can provide important insight into such problems. Some species of fish actively generate an oscillating (c. 1000 Hz) quasi-dipole electric field to communicate and sense their environment in the dark. A specialized electric organ comprises neuron-like cells whose collective signal underlies this electric field. As a step towards understanding the detailed biophysics of signal generation in these fish, we use an anatomically-detailed finite-element modelling approach to reverse-engineer the electric organ signal over one oscillation cycle. We find that the spatiotemporal profile of current along the electric organ constitutes a travelling wave that is well-described by two spatial Fourier components varying in time. The conduction velocity of this wave is faster than action potential conduction in any known neuronal axon (>200 m/s), suggesting that the spatiotemporal features of high-frequency electric organ discharges are not constrained by the conduction velocities of spinal neuron pathways.
authors.affiliation: Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.|Center for Neural Dynamics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
authors.forename: Aaron R
authors.initials: AR
authors.lastname: Shifman
authors.affiliation: Center for Neural Dynamics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.|Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
authors.forename: André
authors.initials: A
authors.lastname: Longtin
authors.affiliation: Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.|Center for Neural Dynamics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
authors.forename: John E
authors.initials: JE
authors.lastname: Lewis
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D004555:Electric Fish / Q000502:physiology*; D004557:Electric Organ / Q000502:physiology*; D004560:Electricity; D005583:Fourier Analysis; D008954:Models, Biological