AI scientists are producing a host of new theories of how our brains learn

Brains learn by being subtly rewired: some connections between neurons, known as synapses, are strengthened, while others must be weakened. But because the brain has billions of neurons, of which millions could be involved in any single task, scientists have puzzled over how the brain knows which synapses to tweak and by how much. Dr Hinton popularised a clever mathematical algorithm known as backpropagation to solve this problem in artificial neural networks. But it was long thought to be too unwieldy to have evolved in the human brain. Now, as AIs are beginning to look increasingly human-like in their abilities, scientists are questioning whether the brain might do something similar after all.