\documentclass{article}
\usepackage[pdftex,active,tightpage]{preview}
\setlength\PreviewBorder{2mm}

\usepackage{amsmath}
\usepackage{tikz}
\usetikzlibrary{shapes, calc, shapes, arrows, snakes}
\newcommand{\width}{0.2}
\begin{document}
\begin{preview}
\tikzset{sigmoid/.style={path picture= {
    \begin{scope}[x=1pt,y=10pt]
      \draw plot[domain=-7:7] (\x,{1/(1 + exp(-\x))-0.5});
    \end{scope}
    }
  }
}

\tikzset{relu/.style={path picture= {
    \begin{scope}[x=7pt,y=6pt]
      \draw plot[domain=-1:0] (\x,0);
      \draw plot[domain=0:1] (\x,\x);
    \end{scope}
    }
  }
}

\tikzstyle{input}=[draw,fill=red!50,circle,minimum size=20pt,inner sep=0pt]
\tikzstyle{hidden}=[draw,fill=green!50,circle,minimum size=20pt,inner sep=0pt]
\tikzstyle{output}=[draw,fill=white,circle,minimum size=20pt,inner sep=0pt]
\tikzstyle{bias}=[draw,dashed,fill=gray!50,circle,minimum size=20pt,inner sep=0pt]
\tikzstyle{layer}=[fill=gray!70]

\tikzstyle{stateTransition}=[->, very thick]

\begin{tikzpicture}[scale=2]

    \node (i0)[bias]  at (0, 0) {1};
    \node (i1)[input] at (0, 0.5) {};
    \node (i2)[input] at (0, 1.0) {};
    \node (i3)[input] at (0, 1.5) {};

    \node (h1)[hidden] at (1, 2.0) {};
    \node (h2)[hidden] at (2, 2.5) {};
    \node (h3)[hidden] at (3, 3.0) {};

    \node (o1)[output] at (4, 3.5) {};
    \node (o2)[output] at (5, 3.5) {};

    \draw[stateTransition] (i0) -- (6, 0);
    \draw[stateTransition] (i1) -- (6, 0.5);
    \draw[stateTransition] (i2) -- (6, 1.0);
    \draw[stateTransition] (i3) -- (6, 1.5);
    \draw[stateTransition] (h1) -- (6, 2.0);
    \draw[stateTransition] (h2) -- (6, 2.5);
    \draw[stateTransition] (h3) -- (6, 3.0);

    \draw[stateTransition] (1, 0) -- (h1);
    \draw[stateTransition] (2, 0) -- (h2);
    \draw[stateTransition] (3, 0) -- (h3);

    \draw[stateTransition] (4, 0) -- (o1);
    \draw[stateTransition] (5, 0) -- (o2);

    \foreach \x in {1,...,3} {
        \pgfmathsetmacro{\limy}{(2+\x) / 2}
        \foreach \y in {0, 0.5, ..., \limy} {
            \node[rectangle,draw=black,fill=black,minimum size=12] (box) at (\x,\y) {};
        }
    }

    \foreach \x in {4,...,5} {
        \foreach \y in {0, ..., 6} {
            \pgfmathsetmacro{\yn}{0.5*\y}
            \node[rectangle,draw=black,fill=white,minimum size=12] (box) at (\x,\yn) {};
        }
    }

%     \node (h11)[hidden, sigmoid] at (1, 1.5) {};
%     \node (h12)[hidden, sigmoid] at (1, 0.5) {};
%     \node[circle, inner sep=0] (h13) at (1,-0.5) {\vdots};
%     \node (h14)[hidden, sigmoid] at (1,-1.5) {};
%     \node (h21)[hidden, relu] at (2, 1.5) {};
%     \node (h22)[hidden, relu] at (2, 0.5) {};
%     \node[circle, inner sep=0] (h23) at (2,-0.5) {\vdots};
%     \node (h24)[hidden, relu] at (2,-1.5) {};

%     \node (o1)[output, sigmoid] at (3,0) {};

%     \draw[stateTransition] (r) -- (h11) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (r) -- (h12) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (r) -- (h13) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (r) -- (h14) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (g) -- (h11) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (g) -- (h12) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (g) -- (h13) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (g) -- (h14) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (b) -- (h11) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (b) -- (h12) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (b) -- (h13) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (b) -- (h11) node [midway,above=-0.06cm] {};

%     \draw[stateTransition] (h11) -- (h21) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h11) -- (h22) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h11) -- (h23) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h11) -- (h24) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h12) -- (h21) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h12) -- (h22) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h12) -- (h23) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h12) -- (h24) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h13) -- (h21) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h13) -- (h22) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h13) -- (h23) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h13) -- (h24) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h14) -- (h21) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h14) -- (h22) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h14) -- (h23) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h14) -- (h21) node [midway,above=-0.06cm] {};

%     \draw[stateTransition] (h21) -- (o1) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h22) -- (o1) node [midway,above=-0.10cm] {};
%     \draw[stateTransition] (h23) -- (o1) node [midway,above=-0.06cm] {};
%     \draw[stateTransition] (h24) -- (o1) node [midway,above=-0.06cm] {};

%     \draw [
%     thick,
%     decoration={
%         brace,
%         mirror,
%         raise=0.5cm
%     },
%     decorate
% ] (1+-\width, -1.8) -- (2+\width, -1.8)
% node [pos=0.5,anchor=north,yshift=-0.55cm] {50\% dropout};
\end{tikzpicture}
\end{preview}
\end{document}