+10 XP

Storing and Plotting Time Series

To plot V(t), store V at every time step during the loop — not just the final value. Use two parallel lists: one for time, one for voltage.

The pattern: initialize empty lists before the loop, append each new value inside the loop. After the loop both lists have the same length — one value per time step.

python
import numpy as np
import matplotlib.pyplot as plt
dt=1e-3; tau=20e-3; el=-60e-3; vr=-70e-3; vth=-50e-3
r=100e6; i_mean=25e-11; t_max=150e-3
v = el
t_list, v_list, i_list = [], [], []
for step in range(int(t_max/dt)):
    t = step * dt
    i_t = i_mean * (1 + np.sin(2 * np.pi * t / 0.01))
    v = v + (dt/tau) * (el - v + r * i_t)
    if v >= vth:
        v = vr
    t_list.append(t * 1000)    # ms
→ Append AFTER the spike check so reset voltage is stored
    v_list.append(v * 1000)    # mV
→ * 1000 converts V→mV for readable axis
    i_list.append(i_t * 1e12)  # pA
fig, (ax1, ax2) = plt.subplots(2, 1, figsize=(8, 5), sharex=True)
→ plt.subplots(2,1): 2 rows, 1 column; sharex links x-axes
ax1.plot(t_list, i_list, color='#1CB0F6')
ax1.set_ylabel('I (pA)'); ax1.set_title('Synaptic Current')
ax2.plot(t_list, v_list, color='#58CC02')
ax2.axhline(y=-50, color='red', linestyle='--', label='Threshold')
ax2.set_ylabel('V (mV)'); ax2.set_xlabel('Time (ms)')
ax2.set_title('Membrane Voltage'); ax2.legend()
plt.tight_layout(); plt.show()

Run this — you should see voltage rising then snapping down at each spike, plus the oscillating current above.