Neurotransmitter fields differ from neural fields in the underlying principle that the state variables are not the neuron action potentials, but the chemical concentration of neurotransmitters in the extracellular space. The dendritic arbor of a new electro-chemical neuron model performs a computation on the surrounding field of neurotransmitters. These fields may represent quantities such as position, force, momentum, or energy. Any computation performed by a neural network has a direct analog to a neurotransmitter field computation. While models that use action potentials as state variables may form associations using matrix operations on a large vector of neuron outputs, the neurotransmitter state model makes it possible for a small number of neurons, even a single neuron, to establish an association between an arbitrary pattern in the input field and an arbitrary output pattern. A single layer of neurons, in effect, performs the computation of a two-layer neural network.
Douglas S. Greer