Calculator Inputs
Formula used
This tool provides two common peak-amplitude approximations.
1) Conductance-based peak (steady-state snapshot)
Assuming a baseline leak conductance gLeak and an inhibitory synaptic conductance gSyn with reversal Einh:
Vpeak = (gLeak·Vrest + gSyn·Einh) / (gLeak + gSyn)
ΔV = (Vpeak − Vrest) · A
ΔV = (Vpeak − Vrest) · A
Here A is the attenuation factor (0–1). This ignores detailed time course and treats the peak like a fast clamp to a conductance-weighted voltage.
2) Current-based peak (Ohmic estimate)
If you know the peak inhibitory current magnitude Ipeak and input resistance Rin:
ΔV(mV) = −|Ipeak(pA)| · Rin(MΩ) · 0.001 · A
Vpeak = Vrest + ΔV
Vpeak = Vrest + ΔV
The constant 0.001 converts pA·MΩ to mV. The negative sign follows the common hyperpolarizing convention for IPSPs.
How to use this calculator
- Select a method that matches your recording or simulation output.
- Enter Vrest. For conductance mode, add Einh and gSyn.
- Choose either gLeak or Rin for the baseline term.
- Set an attenuation factor if the synapse is distal or filtered.
- Press Submit to see results above the form.
Example data table
These example rows illustrate typical parameter ranges and resulting amplitudes.
| Case | Method | Vrest (mV) | Einh (mV) | gSyn (nS) | gLeak (nS) | Atten | IPSP amplitude (mV) |
|---|---|---|---|---|---|---|---|
| A | Conductance | -65 | -75 | 8 | 20 | 1.0 | 2.86 |
| B | Conductance | -62 | -78 | 5 | 15 | 0.7 | 2.80 |
| C | Current | -70 | — | — | — | 0.9 | 4.50 |
Example C uses Ipeak = 500 pA and Rin = 10 MΩ (magnitude shown). Values are illustrative and may vary by cell type, temperature, and recording configuration.