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| 1 | +#!/usr/bin/env python3 |
| 2 | +""" |
| 3 | +Fig. 8 from: |
| 4 | +
|
| 5 | +Brunel, N. Dynamics of Sparsely Connected Networks of Excitatory and |
| 6 | +Inhibitory Spiking Neurons. J Comput Neurosci 8, 183–208 |
| 7 | +(2000). https://doi.org/10.1023/A:1008925309027 |
| 8 | +
|
| 9 | +Inspired by http://neuronaldynamics.epfl.ch |
| 10 | +
|
| 11 | +Sebastian Schmitt, 2022 |
| 12 | +""" |
| 13 | + |
| 14 | +import random |
| 15 | +from brian2 import * |
| 16 | +import matplotlib.pyplot as plt |
| 17 | + |
| 18 | + |
| 19 | +def sim(g, nu_ext_over_nu_thr, sim_time, ax_spikes, ax_rates, rate_tick_step): |
| 20 | + """ |
| 21 | + g -- relative inhibitory to excitatory synaptic strength |
| 22 | + nu_ext_over_nu_thr -- ratio of external stimulus rate to threshold rate |
| 23 | + sim_time -- simulation time |
| 24 | + ax_spikes -- matplotlib axes to plot spikes on |
| 25 | + ax_rates -- matplotlib axes to plot rates on |
| 26 | + rate_tick_step -- step size for rate axis ticks |
| 27 | + """ |
| 28 | + |
| 29 | + # network parameters |
| 30 | + N_E = 10000 |
| 31 | + gamma = 0.25 |
| 32 | + N_I = round(gamma * N_E) |
| 33 | + N = N_E + N_I |
| 34 | + epsilon = 0.1 |
| 35 | + C_E = epsilon * N_E |
| 36 | + C_ext = C_E |
| 37 | + |
| 38 | + # neuron parameters |
| 39 | + tau = 20 * ms |
| 40 | + theta = 20 * mV |
| 41 | + V_r = 10 * mV |
| 42 | + tau_rp = 2 * ms |
| 43 | + |
| 44 | + # synapse parameters |
| 45 | + J = 0.1 * mV |
| 46 | + D = 1.5 * ms |
| 47 | + |
| 48 | + # external stimulus |
| 49 | + nu_thr = theta / (J * C_E * tau) |
| 50 | + |
| 51 | + defaultclock.dt = 0.1 * ms |
| 52 | + |
| 53 | + neurons = NeuronGroup(N, |
| 54 | + """ |
| 55 | + dv/dt = -v/tau : volt (unless refractory) |
| 56 | + """, |
| 57 | + threshold="v > theta", |
| 58 | + reset="v = V_r", |
| 59 | + refractory=tau_rp, |
| 60 | + method="exact", |
| 61 | + ) |
| 62 | + |
| 63 | + excitatory_neurons = neurons[:N_E] |
| 64 | + inhibitory_neurons = neurons[N_E:] |
| 65 | + |
| 66 | + exc_synapses = Synapses(excitatory_neurons, target=neurons, on_pre="v += J", delay=D) |
| 67 | + exc_synapses.connect(p=epsilon) |
| 68 | + |
| 69 | + inhib_synapses = Synapses(inhibitory_neurons, target=neurons, on_pre="v += -g*J", delay=D) |
| 70 | + inhib_synapses.connect(p=epsilon) |
| 71 | + |
| 72 | + nu_ext = nu_ext_over_nu_thr * nu_thr |
| 73 | + |
| 74 | + external_poisson_input = PoissonInput( |
| 75 | + target=neurons, target_var="v", N=C_ext, rate=nu_ext, weight=J |
| 76 | + ) |
| 77 | + |
| 78 | + rate_monitor = PopulationRateMonitor(neurons) |
| 79 | + |
| 80 | + # record from the first 50 excitatory neurons |
| 81 | + spike_monitor = SpikeMonitor(neurons[:50]) |
| 82 | + |
| 83 | + run(sim_time, report='text') |
| 84 | + |
| 85 | + ax_spikes.plot(spike_monitor.t / ms, spike_monitor.i, "|") |
| 86 | + ax_rates.plot(rate_monitor.t / ms, rate_monitor.rate / Hz) |
| 87 | + |
| 88 | + ax_spikes.set_yticks([]) |
| 89 | + |
| 90 | + ax_spikes.set_xlim(*params["t_range"]) |
| 91 | + ax_rates.set_xlim(*params["t_range"]) |
| 92 | + |
| 93 | + ax_rates.set_ylim(*params["rate_range"]) |
| 94 | + ax_rates.set_xlabel("t [ms]") |
| 95 | + |
| 96 | + ax_rates.set_yticks( |
| 97 | + np.arange( |
| 98 | + params["rate_range"][0], params["rate_range"][1] + rate_tick_step, rate_tick_step |
| 99 | + ) |
| 100 | + ) |
| 101 | + |
| 102 | + plt.subplots_adjust(hspace=0) |
| 103 | + |
| 104 | + |
| 105 | +parameters = { |
| 106 | + "A": { |
| 107 | + "g": 3, |
| 108 | + "nu_ext_over_nu_thr": 2, |
| 109 | + "t_range": [500, 600], |
| 110 | + "rate_range": [0, 6000], |
| 111 | + "rate_tick_step": 1000, |
| 112 | + }, |
| 113 | + "B": { |
| 114 | + "g": 6, |
| 115 | + "nu_ext_over_nu_thr": 4, |
| 116 | + "t_range": [1000, 1200], |
| 117 | + "rate_range": [0, 400], |
| 118 | + "rate_tick_step": 100, |
| 119 | + }, |
| 120 | + "C": { |
| 121 | + "g": 5, |
| 122 | + "nu_ext_over_nu_thr": 2, |
| 123 | + "t_range": [1000, 1200], |
| 124 | + "rate_range": [0, 200], |
| 125 | + "rate_tick_step": 50, |
| 126 | + }, |
| 127 | + "D": { |
| 128 | + "g": 4.5, |
| 129 | + "nu_ext_over_nu_thr": 0.9, |
| 130 | + "t_range": [1000, 1200], |
| 131 | + "rate_range": [0, 250], |
| 132 | + "rate_tick_step": 50, |
| 133 | + }, |
| 134 | +} |
| 135 | + |
| 136 | +for panel, params in parameters.items(): |
| 137 | + |
| 138 | + fig = plt.figure(figsize=(4, 5)) |
| 139 | + fig.suptitle(panel) |
| 140 | + |
| 141 | + gs = fig.add_gridspec(ncols=1, nrows=2, height_ratios=[4, 1]) |
| 142 | + |
| 143 | + ax_spikes, ax_rates = gs.subplots(sharex="col") |
| 144 | + |
| 145 | + sim( |
| 146 | + params["g"], |
| 147 | + params["nu_ext_over_nu_thr"], |
| 148 | + params["t_range"][1] * ms, |
| 149 | + ax_spikes, |
| 150 | + ax_rates, |
| 151 | + params["rate_tick_step"], |
| 152 | + ) |
| 153 | + |
| 154 | +plt.show() |
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