Rapid mechanical and thermal changes in the garfish olfactory nerve associated with a propagated impulse

Abstract

Mechanical and thermal changes associated with a propagated nerve impulse were determined using the garfish olfactory nerve. Production of an action potential was found to be accompanied by swelling of the nerve fibers. The swelling starts nearly at the onset of the action potential and reaches its peak at the peak of the action potential. There is a decrease in the length of the fibers while an impulse travels along the fibers. The time-course of the initial heat was determined at room temperature using heat-sensors with a response-time of 2-3 ms. Positive heat production was found to start and reach its peak nearly simultaneously with the action potential. The rise in temperature of the nerve was shown to be 23 (+/- 4) mu degrees C. In the range between 10 degrees and 20 degrees C, the temperature coefficient of heat production is negative, primarily due to prolongation of the period of positive heat production at low temperatures. The amount of heat absorbed during the negative phase varies widely between 45 and 85% of the heat evolved during the positive phase. It is suggested that both mechanical and thermal changes in the nerve fibers are associated with the release and re-binding of Ca-ions in the nerve associated with action potential production.

Solitary electromechanical pulses in lobster neurons

“…It is to be expected that the state of the nerve cell depends not only on electrochemical potentials and the conjugated flux of ions but also on all other thermodynamic forces including variations in lateral pressure (resulting in changes of membrane area and thickness) and temperature (resulting in heat flux). It is therefore not surprising that, during the action potential, one finds changes not only in voltage but also in thickness (3)(4)(5)(6), length (5, 7) as well changes in membrane temperature (8)(9)(10)(11). The change of thickness of a single squid axon was found to be on the order of 1 nm, and temperature changes range between 1-100 µK depending on the specimen.…”

On soliton propagation in biomembranes and nerves

“…nbi.dk͞Kaufmann). In fact, mechanical forces and dislocations as well as temperature responses of nerve membranes in-phase with the action potential have been found experimentally (11)(12)(13)(14)(15)(16). They are accompanied by changes in the fluorescence of membrane probes and changes in turbidity and birefringence (17).…”

High-fidelity numerical simulation of solitons in the nerve axon

“…Timesymmetric integration implies discrete energy-conservation, which is an attractive property for energy-conservative models. The NS model describes an adiabatic and reversible phenomenon [44,18] and should thus ideally be time-integrated with a time-symmetric ODE solver such as (44).…”

“…While the HH model describes various aspects of the voltage pulse traveling along the nerve axon in a satisfactory manner (e.g., its velocity and the pulse amplitude), it fails to describe several other aspects of the nerve pulse that are of nonelectrical nature. It is known that nerves display thickness and length variations under the influence of the voltage pulse and the nerve pulse can be excited by a mechanical stimulus, indicating that the nerve pulse possesses a mechanical component [44]. Furthermore, heat signatures from experimental data [44] indicate that the nerve pulse is an adiabatic and reversible phenomenon such as the propagation of a mechanical wave.…”

“…It is known that nerves display thickness and length variations under the influence of the voltage pulse and the nerve pulse can be excited by a mechanical stimulus, indicating that the nerve pulse possesses a mechanical component [44]. Furthermore, heat signatures from experimental data [44] indicate that the nerve pulse is an adiabatic and reversible phenomenon such as the propagation of a mechanical wave. This later observation is in conflict with the HH model that is based on irreversible dissipative processes (currents through resistors) and should lead to dissipation of heat [18].…”