The first artificial neuron

In 1943, two researchers, Warren McCulloch and Walter Pitts, were the first to write that rule down as something a machine could copy.

Here is their neuron. The three circles on the left send signals. The one in the middle adds them up and fires if the total reaches the threshold of 2. Click the inputs on the left to turn them on and off.

To keep it simple, they made every signal : on or off, nothing in between. One signal isn't enough. Two crosses the line, so the neuron fires.

And here is the part that matters most. When the middle neuron fires, its output can become the input to other neurons further down the chain. Neurons don't only listen to the outside world. They listen to each other. One fires, and that can trigger the next.

The threshold of 2 is just an example. We'll get to where numbers like that come from in a few slides.

The first artificial neuron

In 1943, two researchers, Warren McCulloch and Walter Pitts, were the first to write that rule down as something a machine could copy.

To keep it simple, they made every signal : on or off, nothing in between. One signal isn't enough. Two crosses the line, so the neuron fires.

The threshold of 2 is just an example. We'll get to where numbers like that come from in a few slides.