
\tikzstyle{hidden_neuron}=[circle,draw=blue!50,fill=cyan!10,thick,minimum size=6mm]

\begin{tikzpicture}[scale=0.75]
%     \foreach \i [count=\ii from 1] in {378,234,90,306,162}
% \path (\i:32mm) node (p\ii) {$X_{\ii}$};

	\node [hidden_neuron] (neuron1) at (10,7.5)  {A};
	\node [hidden_neuron] (neuron2) at (8,5.5)  {D};
	\node [hidden_neuron] (neuron3) at (10,3.5)  {C};
	\node [hidden_neuron] (neuron4) at (12,5.5)  {B};
     \draw[blue,thick,->] (neuron1) -- (neuron2); %A->D
     \draw[blue,thick,->] (neuron2) -- (neuron3); %D->C
     \draw[blue,thick,->] (neuron4) -- (neuron3); %B->C
     \draw[blue,thick,->] (neuron1) -- (neuron4); %A->B


\end{tikzpicture}

