Squid Axon Lab — Membrane Action Potential

Membrane Action Potential

Space-clamped Hodgkin–Huxley membrane · current-clamp stimulation

t— ms

Vm— mV

INa— mA/cm²

IK— mA/cm²

Ii— mA/cm²

Plot picked points

Picked points

Right-click anywhere on the plot to record the time and voltage under the cursor.

#	t (ms)	Vm (mV)
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Model: Hodgkin & Huxley (1952) squid giant axon kinetics, reversal potentials from the Goldin–Hodgkin–Katz voltage equation, integrated with Heun's method (Δt = 0.02 ms). Physiology adapted from the Bezanilla Lab NerveJS simulator (nerve.bsd.uchicago.edu) for course use. TTX scales g_Na via gNa /(1 + [TTX]/3 nM); pronase fraction removes Na⁺-channel inactivation.

Voltage Clamp

Command potential is prescribed; gating variables solved exactly (no integration error)

t— ms

Vcmd— mV

INa— mA/cm²

IK— mA/cm²

Ii— mA/cm²

Plot picked points

Gating particles

n m h

Picked points

Right-click any trace — including family runs and overlaid runs — to record its exact values at that point.

#	t (ms)	Vm (mV)
No points yet — right-click the plot.

Same Hodgkin–Huxley kinetics and GHK reversal potentials as the Membrane AP tab, but Vm is commanded rather than solved: within each constant-voltage segment, n, m, and h relax exactly toward their voltage-dependent steady states with time constant τ(V) — x(t) = x_∞ + (x₀ − x_∞)·e^−t/τ. Gating starts pre-equilibrated at the holding potential.