Spatial networks: Convergent projection and rectangular mask, from target perspective

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Create two populations of iaf_psc_alpha neurons on a 30x30 grid

Connect the two populations with convergent projection and rectangular mask and visualize connection from target perspective.

BCCN Tutorial @ CNS*09 Hans Ekkehard Plesser, UMB

import matplotlib.pyplot as plt
import nest
import numpy as np

nest.ResetKernel()
nest.set_verbosity("M_WARNING")

pos = nest.spatial.grid(shape=[30, 30], extent=[3.0, 3.0], edge_wrap=True)

create and connect two populations

a = nest.Create("iaf_psc_alpha", positions=pos)
b = nest.Create("iaf_psc_alpha", positions=pos)

nest.Connect(
    a,
    b,
    conn_spec={
        "rule": "pairwise_bernoulli",
        "p": 0.5,
        "use_on_source": True,
        "mask": {"rectangular": {"lower_left": [-0.2, -0.5], "upper_right": [0.2, 0.5]}},
    },
    syn_spec={"weight": nest.random.uniform(0.5, 2.0)},
)
plt.clf()

plot sources of neurons in different grid locations

for tgt_index in [30 * 15 + 15, 0]:
    # obtain node id for center
    tgt = a[tgt_index : tgt_index + 1]

    # obtain list of outgoing connections for ctr
    spos = nest.GetTargetPositions(tgt, b)[0]

    spos_x = np.array([x for x, y in spos])
    spos_y = np.array([y for x, y in spos])

    print(spos_x)
    print(spos_y)

    # scatter-plot
    plt.scatter(spos_x, spos_y, 20, zorder=10)

    # mark sender position with transparent red circle
    ctrpos = np.array(nest.GetPosition(tgt))
    plt.gca().add_patch(plt.Circle(ctrpos, radius=0.1, zorder=99, fc="r", alpha=0.4, ec="none"))

    # mark mask position with open red rectangle
    plt.gca().add_patch(plt.Rectangle(ctrpos - (0.2, 0.5), 0.4, 1.0, zorder=1, fc="none", ec="r", lw=3))

# mark layer edge
plt.gca().add_patch(plt.Rectangle((-1.5, -1.5), 3.0, 3.0, zorder=1, fc="none", ec="k", lw=3))

# beautify
plt.axes().set_xticks(np.arange(-1.5, 1.55, 0.5))
plt.axes().set_yticks(np.arange(-1.5, 1.55, 0.5))
plt.grid(True)
plt.axis([-2.0, 2.0, -2.0, 2.0])
plt.axes().set_aspect("equal", "box")
plt.title("Connection sources")
plt.show()