PyNEST Microcircuit: Network ParametersΒΆ


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A dictionary with base network and neuron parameters is enhanced with derived parameters.

import numpy as np


def get_exc_inh_matrix(val_exc, val_inh, num_pops):
    """Creates a matrix for excitatory and inhibitory values.

    Parameters
    ----------
    val_exc
        Excitatory value.
    val_inh
        Inhibitory value.
    num_pops
        Number of populations.

    Returns
    -------
    matrix
        A matrix of of size (num_pops x num_pops).

    """
    matrix = np.zeros((num_pops, num_pops))
    matrix[:, 0:num_pops:2] = val_exc
    matrix[:, 1:num_pops:2] = val_inh
    return matrix


net_dict = {
    # factor to scale the number of neurons
    "N_scaling": 0.1,
    # factor to scale the indegrees
    "K_scaling": 0.1,
    # neuron model
    "neuron_model": "iaf_psc_exp",
    # names of the simulated neuronal populations
    "populations": ["L23E", "L23I", "L4E", "L4I", "L5E", "L5I", "L6E", "L6I"],
    # number of neurons in the different populations (same order as
    # 'populations')
    "full_num_neurons": np.array([20683, 5834, 21915, 5479, 4850, 1065, 14395, 2948]),
    # mean rates of the different populations in the non-scaled version of the
    # microcircuit (in spikes/s; same order as in 'populations');
    # necessary for the scaling of the network.
    # The values were obtained by running this PyNEST microcircuit without MPI,
    # 'local_num_threads' 4 and both 'N_scaling' and 'K_scaling' set to 1.
    "full_mean_rates": np.array([0.903, 2.965, 4.414, 5.876, 7.569, 8.633, 1.105, 7.829]),
    # connection probabilities (the first index corresponds to the targets
    # and the second to the sources)
    "conn_probs": np.array(
        [
            [0.1009, 0.1689, 0.0437, 0.0818, 0.0323, 0.0, 0.0076, 0.0],
            [0.1346, 0.1371, 0.0316, 0.0515, 0.0755, 0.0, 0.0042, 0.0],
            [0.0077, 0.0059, 0.0497, 0.135, 0.0067, 0.0003, 0.0453, 0.0],
            [0.0691, 0.0029, 0.0794, 0.1597, 0.0033, 0.0, 0.1057, 0.0],
            [0.1004, 0.0622, 0.0505, 0.0057, 0.0831, 0.3726, 0.0204, 0.0],
            [0.0548, 0.0269, 0.0257, 0.0022, 0.06, 0.3158, 0.0086, 0.0],
            [0.0156, 0.0066, 0.0211, 0.0166, 0.0572, 0.0197, 0.0396, 0.2252],
            [0.0364, 0.001, 0.0034, 0.0005, 0.0277, 0.008, 0.0658, 0.1443],
        ]
    ),
    # mean amplitude of excitatory postsynaptic potential (in mV)
    "PSP_exc_mean": 0.15,
    # relative standard deviation of the weight
    "weight_rel_std": 0.1,
    # relative inhibitory weight
    "g": -4,
    # mean delay of excitatory connections (in ms)
    "delay_exc_mean": 1.5,
    # mean delay of inhibitory connections (in ms)
    "delay_inh_mean": 0.75,
    # relative standard deviation of the delay of excitatory and
    # inhibitory connections
    "delay_rel_std": 0.5,
    # turn Poisson input on or off (True or False)
    # if False: DC input is applied for compensation
    "poisson_input": True,
    # indegree of external connections to the different populations (same order
    # as in 'populations')
    "K_ext": np.array([1600, 1500, 2100, 1900, 2000, 1900, 2900, 2100]),
    # rate of the Poisson generator (in spikes/s)
    "bg_rate": 8.0,
    # delay from the Poisson generator to the network (in ms)
    "delay_poisson": 1.5,
    # initial conditions for the membrane potential, options are:
    # 'original': uniform mean and standard deviation for all populations as
    #             used in earlier implementations of the model
    # 'optimized': population-specific mean and standard deviation, allowing a
    #              reduction of the initial activity burst in the network
    #              (default)
    "V0_type": "optimized",
    # parameters of the neuron model
    "neuron_params": {
        # membrane potential average for the neurons (in mV)
        "V0_mean": {"original": -58.0, "optimized": [-68.28, -63.16, -63.33, -63.45, -63.11, -61.66, -66.72, -61.43]},
        # standard deviation of the average membrane potential (in mV)
        "V0_std": {"original": 10.0, "optimized": [5.36, 4.57, 4.74, 4.94, 4.94, 4.55, 5.46, 4.48]},
        # reset membrane potential of the neurons (in mV)
        "E_L": -65.0,
        # threshold potential of the neurons (in mV)
        "V_th": -50.0,
        # membrane potential after a spike (in mV)
        "V_reset": -65.0,
        # membrane capacitance (in pF)
        "C_m": 250.0,
        # membrane time constant (in ms)
        "tau_m": 10.0,
        # time constant of postsynaptic currents (in ms)
        "tau_syn": 0.5,
        # refractory period of the neurons after a spike (in ms)
        "t_ref": 2.0,
    },
}

# derive matrix of mean PSPs,
# the mean PSP of the connection from L4E to L23E is doubled
PSP_matrix_mean = get_exc_inh_matrix(
    net_dict["PSP_exc_mean"], net_dict["PSP_exc_mean"] * net_dict["g"], len(net_dict["populations"])
)
PSP_matrix_mean[0, 2] = 2.0 * net_dict["PSP_exc_mean"]

updated_dict = {
    # matrix of mean PSPs
    "PSP_matrix_mean": PSP_matrix_mean,
    # matrix of mean delays
    "delay_matrix_mean": get_exc_inh_matrix(
        net_dict["delay_exc_mean"], net_dict["delay_inh_mean"], len(net_dict["populations"])
    ),
}

net_dict.update(updated_dict)

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