$I_k^{\text{fields}}$

the additional injected current at the node, due to the ambient superposed electric fields near the node

$\sigma$

the local conductivity of the medium near the nodal surface

$\overleftarrow{E^{\text{impinging}}}$

the algebraic sum of impinging fields from relevant nodes, the fields themselves depending on the states of those nodes

$W,W_{ip}\left(z\right)$

the matrix of inter-axonal distances (without, with) z-dependence

$m\mathrm{,}n,\tilde{h},p$

activation and inactivation variables

$N_{Na},N_K$

expected number of open (sodium, potassium) pores

$\kappa$

electric field-based coupling gain, based on the sodium ion

h

gravitational strain

ds

invariant spacetime interval

$x\mathrm{,}y\mathrm{,}\tilde{z}\mathrm{,}t$

spatial and temporal coordinates

c

speed of light

f

frequency of the gravitational wave