Hidden Neuron, Hidden Layer Neuron - In traditional feed-forward
neural networks, a
hidden layer neuron is a neuron whose output is connected to the inputs of other neurons and is therefor not visible as a network output (hence the term hidden layer).
In the context of a feed-forward network, a hidden layer neuron is a
pre-synaptic neuron because it is connected to other neurons in the network which are
post-synaptic in relation to its output. In feed-forward networks, neurons form layers, or slabs, which are connected to and from post- and pre- synaptic neurons. Such groupings of neurons that are themselves connected to other neurons are sometimes (traditionally) called hidden layers or hidden layer nuerons.
Using the more general terms: "
post synaptic" and "
pre-synaptic" allows any given parties to a connection, or set of connections, to be discussed without inadvertently dragging the entire network into the discussion; or perhaps is is more correct to say: without imposing a feed-forward-only structural limit on the discussion.