Work initiated by Alan Turing on theoretical models of computation around the same time also showed that computation requires a nonlinearity. A system that simply creates weighted sums of its inputs cannot perform the essential requirements of computation. We now know that actual biological neurons have many other nonlinearities resulting from the electrochemical action of the synapses and the morphology (shape) of the dendrites. Different arrangements of biological neurons can perform computations, including adding, subtracting, multiplying, dividing, averaging, filtering, normalizing, and
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