Deep Learning: Professor Geoffrey Hinton FRS, 25 June 2015

I will describe an efficient, unsupervised learning procedure for a simple type of two-layer neural network called a Restricted Boltzmann Machine. The fact that backpropagation learning is now the method of choice for a wide variety of really difficult tasks means that neuroscientists may need to reconsider their well-worn arguments about why it cannot possibly be occurring in cortex. I shall conclude by undermining two of the commonest objections to the idea that cortex is actually backpropagating error derivatives through a hierarchy of cortical areas and I shall show that spike-time dependent plasticity is a signature of backpropagation.