def METHOD_NAME(self):
    """Masked connect sliced grid spatial source population"""
    nodes = nest.Create("iaf_psc_alpha", positions=self.grid_pos)
    nest.Connect(
        nodes[self.middle_node],
        nodes,
        conn_spec={"rule": "pairwise_bernoulli", "p": self.parameter, "mask": self.mask},
    )
    self._assert_histogram(nest.GetConnections().target, self.reference_masked)