Walter Pitts

American logician who co-wrote with Warren McCullochWarren McCulloch, prop. n.: An American brain scientist who, with Walter Pitts, wrote the 1943 paper that first described nerve cells as simple logic units, the seed of today's artificial neural networks. the 1943 paper introducing the McCulloch–Pitts neuronMcCulloch–Pitts neuron, n.: The first mathematical model of a brain cell as a simple on–off switch: it fires if enough of its inputs are on and no blocking input is. Networks of them can carry out logic., a threshold logic unit that became the starting point for artificial neuronsartificial neuron, n.: The basic building block of a neural network: a tiny calculator that multiplies each incoming number by a weight, adds them up, and passes the total through a simple function to decide its output. and neural networksneural network, n.: A kind of computer program that learns a task from examples by tuning thousands to billions of connections between simple number-crunching units, an arrangement loosely inspired by nerve cells in the brain.; he was 20 when it appeared and had no university degree, which he never obtained. He then joined Norbert WienerNorbert Wiener, prop. n.: An American mathematician who founded cybernetics, the study of feedback and control in animals and machines, and warned early that machines might pursue goals we did not truly intend. at MIT and took part in the founding of cyberneticscybernetics, n.: The study of how animals, machines and organizations steer themselves using feedback: sensing the result of an action and correcting course. It was both a parent and an early rival of AI.. With McCulloch he wrote 'How We Know Universals' (1947), an early neural model of recognizing patterns regardless of position or size, and with Jerome Lettvin, Humberto Maturana and McCulloch he co-wrote 'What the Frog's Eye Tells the Frog's Brain' (1959), which showed that the retina itself detects features such as small moving objects. He published little after the late 1950s.