\documentclass[border=15pt, multi, tikz]{standalone}
%\usepackage{blocks}
\usepackage{import}
\subimport{../../layers/}{init}
\usetikzlibrary{positioning}

\newcommand{\midarrow}{\tikz \draw[-Stealth,line width =0.8mm,draw=\edgecolor] (-0.3,0) -- ++(0.3,0);}
\newcommand{\up}{0.25}
\newcommand{\down}{0.25}
\newcommand{\arrowlength}{4}

\begin{document}
\begin{tikzpicture}
\tikzstyle{connection}=[ultra thick,every node/.style={sloped,allow upside down},draw=\edgecolor,opacity=0.7]
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Draw Layer Blocks
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% conv1_1,conv1_2,pool1
\pic[shift={(0,0,0)},fill={rgb:blue,1.5;red,3.5;green,3.5;white,5}] at (0,0,0) {GenericSequentialLayer={blockname=crp1,%
    numFilters={{" ",""}},height=20,width={7},depth=20, blocklabel=SoftmaxLoss: $E_\mathcal{S}$ ,ylabel= ,zlabel= }};

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Draw connections
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\draw [connection]  (crp1-east)++(0,\up,0) -- node {\midarrow} ++(\arrowlength.0,0) 
node [anchor=south east,scale=2.1]{$E_\mathcal{S} [p;\theta]$};
\draw (crp1-west)++(0,\up,0) coordinate (crp1-west-up);
\draw [connection]  (crp1-west-up)++(-\arrowlength,0,0) 
node[anchor=south west,scale=2.1]{$p(x^{(t)})$}   
-- node {\midarrow} (crp1-west-up);  

\draw [connection]  (crp1-west)++(0,-\down,0)     -- node {\midarrow} ++(-\arrowlength.0,0)
node[anchor=north west,inner sep = 10, xshift=-25,scale=2.3]
{
    $\frac{\partial L}{\partial E_\mathcal{S}}\frac{\partial E_\mathcal{S}}{\partial p}$
};
\draw (crp1-east)++(0,-\down,0) coordinate (crp1-east-down);
\draw [connection]  (crp1-east-down)++(\arrowlength,0,0)  
node[anchor=north east,inner sep = 10, xshift=25,scale=2.3]
{
    $\frac{\partial L}{\partial E_\mathcal{S}} = \lambda_\mathcal{S}$
}   
-- node {\midarrow} (crp1-east-down);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   		

\end{tikzpicture}
\end{document}