Neuron Simulation
Recruitable membranes, refractory bottlenecks, and firing phenotypes
The neuron lab now teaches more than a clean membrane trace. It frames the LIF model as a way to compare quiet reserve, near-threshold recruitment, stable repetitive firing, and refractory-limited high drive without pretending this is a full conductance-level disease simulator.
Teaching presets
Start from an excitability phenotype
Each preset is a teaching frame for a different recruitment story: silent reserve, borderline recruitment, regular spiking, or refractory-limited high drive.
Quiet reserve
Subthreshold integration where the membrane is driven upward but never cleanly escapes into repetitive spiking.
Useful for teaching hypoexcitability, weak synaptic drive, or why a neuron can look engaged without actually recruiting output.
Silence here reflects a simple threshold model, not a diagnosis or a channel-level disease state.
Membrane trace
Voltage over time
State map
Return map
The loop away from the identity line turns threshold crossing and reset into one compact picture of each firing cycle.
Output timing
Cumulative spikes
Plateaus between steps average 34.2 ms, so you can see how quickly each spike is recruited into the next one.
Band occupancy
Where the membrane spends its time
Most sampled points live between -62 to -40 mV, which is the band that actually defines the phenotype more than the brief spike apex does.
Phenotype
Stable repetitive recruitment
Drive exceeds threshold enough to produce a steady cycle of integration, threshold crossing, reset, and recovery without becoming dominated by the refractory ceiling.
Spikes
3
Raw output count across the full simulation window.
Firing rate
30.0 Hz
A quick read on how strongly the neuron is recruited into repetitive output.
Mean ISI
34.2 ms
Long intervals suggest sparse recruitment; short intervals suggest denser output.
Steady-state V
-50.0 mV
The simple equilibrium estimate for how far drive would depolarize the membrane without spiking.
Threshold slack
+5.0 mV
Positive means the drive wants to live above threshold; negative means it still settles below it.
Refractory occupancy
6.0%
How much of the run is effectively spent in the recovery pause rather than integrating.
Clinical lens
What this regime teaches
This is the cleanest baseline for teaching how a simple neuron turns continuous input into discrete output.
Bedside signals
What learners should notice
- The membrane ramp is visible between spikes instead of collapsing into near-continuous firing.
- Input current, threshold, and refractory period all remain interpretable levers.
- The output is rhythmic enough to reason about but not so extreme that one parameter dominates everything.
Differential traps
What not to overclaim
- Regular spiking does not identify a specific cortical neuron subtype by itself.
- A clean spike train in LIF is a teaching abstraction, not a full conductance-based explanation.
What to notice
- With 2.0 nA of drive, the model settles into a regular spiking output.
- The steady-state membrane estimate is -50.0 mV, which is above threshold by 5.0 mV.
- Once recruited, the mean interspike interval is 34.2 ms.
- Integration and threshold remain the main levers; refractoriness has not yet taken over the phenotype.
Biological analogies
tau
Membrane time constant. Larger values make the membrane integrate more slowly before leak drags it back.
restingPotential
Baseline voltage set by ionic gradients and leak channels, usually near -70 mV in a typical neuron.
threshold
The voltage where voltage-gated sodium channels would open strongly enough to trigger a spike.
resetPotential
A stylized after-hyperpolarization that follows a spike before the membrane starts integrating again.
refractoryPeriod
The brief interval where sodium channels are inactivated and the neuron cannot immediately spike again.
inputCurrent
A stand-in for synaptic drive from other neurons. More current pushes the membrane toward threshold faster.
Next questions
Useful follow-up experiments
- How far can threshold move before the regime stops firing regularly?
- What changes first when current rises: firing rate, spike count, or refractory occupancy?
Continue the loop
Carry this into channels, learning, and tutoring
Action Potential (Hodgkin-Huxley)
Advanced biophysics and pharmacology
Synaptic Plasticity
Mechanistic learning theory
Neuro Tutor
Cross-module consult reasoning with explicit scoring