  Inferring directional couplings from the spike data of networks is desired in
various scientific fields such as neuroscience. Here, we apply a recently
proposed objective procedure to the spike data obtained from the
Hodgkin--Huxley type models and in vitro neuronal networks cultured in a
circular structure. As a result, we succeed in reconstructing synaptic
connections accurately from the evoked activity as well as the spontaneous one.
To obtain the results, we invent an analytic formula approximately implementing
a method of screening relevant couplings. This significantly reduces the
computational cost of the screening method employed in the proposed objective
procedure, making it possible to treat large-size systems as in this study.
