It sounds like an action potential: unification of electrical, chemical and mechanical aspects of acoustic pulses in lipids

Abstract

<jats:p>In an ongoing debate on the physical nature of the action potential (AP), one group adheres to the electrical model of Hodgkin and Huxley, while the other describes the AP as a nonlinear acoustic pulse propagating within an interface near a transition. However, despite remarkable similarities, acoustics remains a non-intuitive mechanism for APs for the following reason. While acoustic pulses are typically associated with the propagation of density, pressure and temperature variation, APs are most commonly measured electrically. Here, we show that this discrepancy is lifted upon considering the electrical and chemical aspects of the interface, in addition to its mechanical properties. Specifically, we demonstrate how electrical and pH aspects of acoustic pulses emerge from an idealized description of the lipid interface, which is based on classical physical principles and contains no fit parameters. The pulses that emerge from the model show similarities to APs not only in qualitative shape and scales (time, velocity and voltage), but also demonstrate saturation of amplitude and annihilation upon collision.</jats:p>

Temperature changes accompanying signal propagation in axons

“…4. The idea behind including J and U as sources is that mechanisms where the temperature increase is caused by the current flowing through the environment or by the deformation of the solid are well established in the physics even if these are not as common sources assumed for the heat generation [10,12] as the correlation with the AP [11,15,17].…”

“…The potential Z of the AP or its square Z 2 might be not the only sources. For example, in [10,12] it is argued in favour of the idea that experimentally observed temperature changes might be the result of the propagating mechanical wave in the lipid bi-layer. As there seems to be no clear consensus which quantities associated with the nerve pulse propagation are the sources of the thermal energy, we will consider here all the possibilities for the coupling of the waves in the ensemble to the additional model equation for the temperature.…”

High-speed interferometric imaging reveals dynamics of neuronal deformation during the action potential

“…Until now, the entire picture of how neurons move during the action potential was unclear, and the underlying mechanism remains poorly understood. Several hypotheses have been proposed to explain the membrane displacement during the action potential in axons, including electrostriction (10), converse flexoelectricity (11,12), and soliton wave (13,14). High-speed and wide-field imaging of the spatiotemporal dynamics of neuronal deformations during the action potential, as achieved in this work, should add an additional tool to help resolve the electromechanical coupling mechanism.…”

Dedalus: A flexible framework for numerical simulations with spectral methods

“…While its development has been motivated by the study of turbulent flows in astrophysics and geophysics, Dedalus is capable of solving a much broader range of PDEs. To date, it has been used for applications and publications in applied mathematics [13][14][15][16], astrophysics [17][18][19][20][21][22][23][24][25][26][27][28][29][30], atmospheric science [31][32][33][34][35], biology [36][37][38], fluid dynamics [39][40][41][42][43][44][45][46][47], glaciology [48], numerical analysis [49][50][51][52], oceanography [53][54][55], planetary science [56,57], and plasma physics [58][59][60].…”