From: Linking demyelination to compound action potential dispersion with a spike-diffuse-spike approach
Variable | Name | Units |
---|---|---|
β | Stochastic scaling | mV^{−1} |
\(\delta T_{i}\) | Internodal delay in units of membrane time constant | – |
\(\delta T_{N}\) | Internodal delay for whole axon | – |
\(\delta T_{TP}\) | Mean internodal delay for whole axon and averaged across lesion configurations | – |
ϕ | Normaliozed extracellular potential | – |
θ | Stochastic threshold | mV |
γ | Ratio of length constants | – |
\(\lambda_{i} \) | Electrotonic length constant of ith internode | mm |
\(\lambda_{M}\) | Electrotonic length constant of a myelinated segment | mm |
\(\lambda_{D}\) | Electotonic length constant of a damaged segment | mm |
\(\lambda_{L}\) | Electrotonic length constant of a fully demyelinated segment | mm |
\(\rho_{i}\) | Firing hazard of node i | – |
\(\sigma^{2}_{TP}\) | Variance of transmission delay across lesion configurations | – |
\(\sigma_{e}\) | Electric permittivity | – |
τ | Membrane time constant | ms |
D | Internodal distance in units of electrotonic length constant | – |
\(G_{i}(T,X)\) | Green’s function of internodal propagation | mV / pA |
\(I_{\mathrm{AP}}\) | AP current influx | pA |
k | Lesion size | Number of internodes |
\(N_{ij}\) | Number of nodes in configration ij | – |
\(N_{L}\) | Total number of lesions | – |
N̅ | Mean number of lesions | – |
\(p_{L}\) | Frequency of lesions | Lesions per node |
\(P_{T}^{(i)}\) | Probability of transmission across internode i | – |
\(P_{T}^{(\mathrm{axon})} \) | Probability of transmission across whole axon | – |
\(p_{i}(T,X)\) | Probability of firing first spike at node i – | |
\(T_{i}\) | Time of action potential in node i and in units of membrane time constant | – |
t | Time from action potential | ms |
\(V_{i}(T,X)\) | Membrane potential deflection along internode i | mV |
v | Propagation speed | m/s |
X | Distance along internode in units of electrotonic constant | – |
x | Distance along internode | mm |