Components of a McCulloch-Pitts neuron
Excitatory inputs, xi:
Excitatory inputs have values in {0, 1}. Each one contributes equally
to the activation of the unit.
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Inhibitory inputs, xn+j:
Inhibitory inputs have values in {0, 1}.
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Threshold, u:
The threshold is an integer (it could be any real number, but there is
no point in this!).
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Neuron Output, y:
The output, whose values are in {0, 1}, is computed as follows.
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If a unit has at least one inhibitory input whose value is 1, then the
unit is inhibited and its output is 0, regardless of the excitatory inputs.
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Provided the unit is not inhibited, its total excitation is computed
by summing the n excitatory inputs: x = x1 + x2 + ... + xn.
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The result is compared with the threshold u. If x >= u the unit output
is set to 1, and if x < u then the output is 0. (I.e., the McCulloch-Pitts
neuron has a unit step activation function.)
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