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SandraMeshack
SandraMeshack

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Sample Code on how to build a ten neuron SNN USING STDP Learning rule

import numpy as np import matplotlib.pyplot as plt # Parameters num_neurons = 10 num_layers = 3 num_timesteps = 100 dt = 0.001 # Neuron model V_rest = -70 V_threshold = -55 V_reset = -75 tau_m = 0.02 tau_ref = 0.002 # Synaptic connections W_ff = np.random.rand(num_neurons, num_neurons) * 0.1 W_fb = np.random.rand(num_neurons, num_neurons) * 0.1 # Spike-Timing Dependent Plasticity (STDP) learning rule tau_stdp = 0.02 A_plus = 0.01 A_minus = -0.01 # Input data X = np.random.rand(num_neurons, num_timesteps) # Initialize variables V = np.zeros((num_neurons, num_timesteps)) V[:, 0] = V_rest spikes = np.zeros((num_neurons, num_timesteps)) # Simulation loop for t in range(1, num_timesteps): # Calculate feedforward current I_ff = np.dot(W_ff, spikes[:, t-1]) # Calculate feedbackward current I_fb = np.dot(W_fb, spikes[:, t-1]) # Calculate total input current I_in = X[:, t] + I_ff + I_fb # Update membrane potential V[:, t] = V[:, t-1] + (-V[:, t-1] + V_rest + I_in * dt / tau_m) / tau_m # Generate spikes spike_indices = np.where(V[:, t] > V_threshold)[0] spikes[spike_indices, t] = 1 V[spike_indices, t] = V_reset # Refractory period refractory_indices = np.where(spikes[:, t-1] == 1)[0] V[refractory_indices, t] = V_rest # STDP learning rule for i in range(num_neurons): for j in range(num_neurons): if spikes[i, t-1] == 1 and spikes[j, t] == 1: delta_w = A_plus * np.exp(-(t - 1 - tau_stdp) / tau_stdp) W_ff[i, j] += delta_w elif spikes[i, t-1] == 0 and spikes[j, t] == 1: delta_w = A_minus * np.exp(-(t - 1 - tau_stdp) / tau_stdp) W_fb[j, i] += delta_w # Plot results plt.figure(figsize=(10, 6)) plt.subplot(2, 1, 1) plt.title("Membrane Potential") plt.plot(V.T) plt.xlabel("Time") plt.ylabel("Voltage (mV)") plt.ylim(V_reset - 10, V_threshold + 10) plt.subplot(2, 1, 2) plt.title("Spikes") plt.plot(spikes.T, ".") plt.xlabel("Time") plt.ylabel("Spike") plt.show() 
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Please note that you can always change the parameters based on the type of network you are building and you can always change the learning rules too. Please run this, make changes that suit your network and let me know what you have done.
Happy coding.

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Andreas Lie Massey

Thanks!