In a brain, each neuron is connected to thousands of others. Neurons send signals to each other using tiny electrical discharges called spikes. When a neuron receives the right number of spikes from other neurons at the right time, those incoming spikes make a pattern, like tapping a tune with your fingers.
If the pattern matches one that the neuron has learned through experience, like a certain tune that it has heard before, it will send out a spike of its own to the thousands of other neurons that it connects to. That spike will add to the tunes being heard by all those other neurons.
Normal computers can perform precision calculations with blinding speed, but brains can deal with imprecision and vague decisions in a constantly changing world. We hope to learn more by studying the brains of animals and people, and also by building brain-like computers and studying what they’re capable of doing.
One of the clues seems to be that the ‘tunes’ a neuron hears don’t need to be exact. They can be out of time, or have missing notes, but the neuron will still respond. This helps give the brain the ability to deal with the vagueness and unpredictability of the real world.