A demonstration of the responses of different standard neuron models to synaptic inputΒΆ

../_images/synaptic_input_neuron_20151005-081208.png
"""
A demonstration of the responses of different standard neuron models to synaptic input.

This should show that for the current-based synapses, the size of the excitatory
post-synaptic potential (EPSP) is constant, whereas for the conductance-based
synapses it depends on the value of the membrane potential.


Usage: python synaptic_input.py [-h] [--plot-figure] [--debug] simulator

positional arguments:
  simulator      neuron, nest, brian or another backend simulator

optional arguments:
  -h, --help     show this help message and exit
  --plot-figure  Plot the simulation results to a file.
  --debug        Print debugging information

"""

from quantities import ms
from pyNN.utility import get_simulator, init_logging, normalized_filename


# === Configure the simulator ================================================

sim, options = get_simulator(("--plot-figure", "Plot the simulation results to a file.", {"action": "store_true"}),
                             ("--debug", "Print debugging information"))

if options.debug:
    init_logging(None, debug=True)

sim.setup(timestep=0.01, min_delay=1.0)


# === Build and instrument the network =======================================

# for each cell type we create two neurons, one of which we depolarize with
# injected current

cuba_exp = sim.Population(2, sim.IF_curr_exp(tau_m=10.0, i_offset=[0.0, 1.0]),
                          initial_values={"v": [-65, -55]}, label="Exponential, current-based")
cuba_alpha = sim.Population(2, sim.IF_curr_alpha(tau_m=10.0, i_offset=[0.0, 1.0]),
                            initial_values={"v": [-65, -55]}, label="Alpha, current-based")
coba_exp = sim.Population(2, sim.IF_cond_exp(tau_m=10.0, i_offset=[0.0, 1.0]),
                          initial_values={"v": [-65, -55]}, label="Exponential, conductance-based")
coba_alpha = sim.Population(2, sim.IF_cond_alpha(tau_m=10.0, i_offset=[0.0, 1.0]),
                            initial_values={"v": [-65, -55]}, label="Alpha, conductance-based")
v_step = sim.Population(2, sim.Izhikevich(i_offset=[0.0, 0.002]),
                        initial_values={"v": [-70, -67], "u": [-14, -13.4]}, label="Izhikevich")

# we next create a spike source, which will emit spikes at the specified times

spike_times = [25, 50, 80, 90]
stimulus = sim.Population(1, sim.SpikeSourceArray(spike_times=spike_times), label="Input spikes")

# now we connect the spike source to each of the neuron populations, with differing synaptic weights

all_neurons = cuba_exp + cuba_alpha + coba_exp + coba_alpha + v_step

connections = [sim.Projection(stimulus, population,
                              connector=sim.AllToAllConnector(),
                              synapse_type=sim.StaticSynapse(weight=w, delay=2.0),
                              receptor_type="excitatory")
               for population, w in zip(all_neurons.populations, [1.6, 4.0, 0.03, 0.12, 1.0])]

# finally, we set up recording of the membrane potential

all_neurons.record('v')


# === Run the simulation =====================================================

sim.run(100.0)


# === Calculate the height of the first EPSP =================================

print("Height of first EPSP:")
for population in all_neurons.populations:
    # retrieve the recorded data
    vm = population.get_data().segments[0].filter(name='v')[0]
    # take the data between the first and second incoming spikes
    vm12 = vm.time_slice(spike_times[0] * ms, spike_times[1] * ms)
    # calculate and print the EPSP height
    for channel in (0, 1):
        v_init = vm12[:, channel][0]
        height = vm12[:, channel].max() - v_init
        print("  {:<30} at {}: {}".format(population.label, v_init, height))

# === Save the results, optionally plot a figure =============================

filename = normalized_filename("Results", "synaptic_input", "pkl", options.simulator)
all_neurons.write_data(filename, annotations={'script_name': __file__})

if options.plot_figure:
    from pyNN.utility.plotting import Figure, Panel
    figure_filename = filename.replace("pkl", "png")
    Figure(
        Panel(cuba_exp.get_data().segments[0].filter(name='v')[0],
              ylabel="Membrane potential (mV)",
              data_labels=[cuba_exp.label], yticks=True, ylim=(-66, -50)),
        Panel(cuba_alpha.get_data().segments[0].filter(name='v')[0],
              data_labels=[cuba_alpha.label], yticks=True, ylim=(-66, -50)),
        Panel(coba_exp.get_data().segments[0].filter(name='v')[0],
              data_labels=[coba_exp.label], yticks=True, ylim=(-66, -50)),
        Panel(coba_alpha.get_data().segments[0].filter(name='v')[0],
              data_labels=[coba_alpha.label], yticks=True, ylim=(-66, -50)),
        Panel(v_step.get_data().segments[0].filter(name='v')[0],
              xticks=True, xlabel="Time (ms)",
              data_labels=[v_step.label], yticks=True, ylim=(-71, -65)),
        title="Responses of standard neuron models to synaptic input",
        annotations="Simulated with %s" % options.simulator.upper()
    ).save(figure_filename)
    print(figure_filename)

# === Clean up and quit ========================================================

sim.end()