title: Solitary electromechanical pulses in lobster neurons.
abstract: Investigations of nerve activity have focused predominantly on electrical phenomena. Nerves, however, are thermodynamic systems, and changes in temperature and in the dimensions of the nerve can also be observed during the action potential. Measurements of heat changes during the action potential suggest that the nerve pulse shares many characteristics with an adiabatic pulse. First experiments in the 1980s suggested small changes in nerve thickness and length during the action potential. Such findings have led to the suggestion that the action potential may be related to electromechanical solitons traveling without dissipation. However, there have been no modern attempts to study mechanical phenomena in nerves. Here, we present ultrasensitive AFM recordings of mechanical changes on the order of 2-12Å in the giant axons of the lobster. We show that the nerve thickness changes in phase with voltage changes. When stimulated at opposite ends of the same axon, colliding action potentials pass through one another and do not annihilate. These observations are consistent with a mechanical interpretation of the nervous impulse.
authors.affiliation: Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen Ø, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Gonzalez-Perez
authors.affiliation: Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen Ø, Denmark.
authors.forename: L D
authors.initials: LD
authors.lastname: Mosgaard
authors.affiliation: Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen Ø, Denmark.
authors.forename: R
authors.initials: R
authors.lastname: Budvytyte
authors.affiliation: Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen Ø, Denmark; Universidad de La Salle Bajio, Mexico.
authors.forename: E
authors.initials: E
authors.lastname: Villagran-Vargas
authors.affiliation: Niels Bohr International Academy, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen, Denmark.
authors.forename: A D
authors.initials: AD
authors.lastname: Jackson
authors.affiliation: Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen Ø, Denmark. Electronic address: theimbu@nbi.ku.dk.
authors.forename: T
authors.initials: T
authors.lastname: Heimburg
mesh_terms: D000200:Action Potentials; D000818:Animals; D001369:Axons; D001696:Biomechanical Phenomena; D018625:Microscopy, Atomic Force; D008121:Nephropidae; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D013696:Temperature; D013816:Thermodynamics
keywords: Action potential; Atomic force microscopy; Electromechanics; Heat capacitance; Nerve pulse collision