nt(c+1) = nt(c) + dt * (An(c) *(1-nt(c)) - Bn(c) * nt(c)); mt(c+1) = mt(c) + dt * (Am(c) *(1-mt(c)) - Bm(c) * mt(c)); ht(c+1) = ht(c) + dt * (Ah(c) *(1-ht(c)) - Bh(c) * ht(c)); Fig. 7. Variation in the gate variables, conductances and current densities for a voltage-clamp applied to the axon. The depolarization produced by the clamp causes a transient increase in Na+ into the cell. The rise in the K+ current from the cell occurs more slowly and is maintained as long as the membrane is depolarized. The rate of rise of the Na+ and K+ currents increases with increasing size of the voltage clamp and the peak values of Na+ and K+ currents are significantly increased as the clamp voltage is increased, the peak values are over 100 times the magnitudes in the resting membrane. bp_neuron_02.m ACTION POTENTIAL SIMULATION The equations listed below constitute the complete set of equations to describe the membrane current in a squid axon and membrane voltage. (10) (11) (16) (17) (13) (18) (19a) (19b) (19c) We will consider an axially clamped axon the interior potential does not depend upon the location x along its length: V(t,x) = V(t). Since the membrane voltage V does not depend upon x the second derivative in equation (10) is zero (20)
nt(c+1) = nt(c) + dt * (An(c) *(1-nt(c)) - Bn(c) * nt(c)); mt(c+1) = mt(c) + dt * (Am(c) *(1-mt(c)) - Bm(c) * mt(c)); ht(c+1) = ht(c) + dt * (Ah(c) *(1-ht(c)) - Bh(c) * ht(c)); Fig. 7. Variation in the gate variables, conductances and current densities for a voltage-clamp applied to the axon. The depolarization produced by the clamp causes a transient increase in Na+ into the cell. The rise in the K+ current from the cell occurs more slowly and is maintained as long as the membrane is depolarized. The rate of rise of the Na+ and K+ currents increases with increasing size of the voltage clamp and the peak values of Na+ and K+ currents are significantly increased as the clamp voltage is increased, the peak values are over 100 times the magnitudes in the resting membrane. bp_neuron_02.m ACTION POTENTIAL SIMULATION The equations listed below constitute the complete set of equations to describe the membrane current in a squid axon and membrane voltage. (10) (11) (16) (17) (13) (18) (19a) (19b) (19c) We will consider an axially clamped axon the interior potential does not depend upon the location x along its length: V(t,x) = V(t). Since the membrane voltage V does not depend upon x the second derivative in equation (10) is zero (20)
bp_HH_01.docx