A neural processing element for use in a modular neural network is provided. One embodiment provides a neural network comprising an array of autonomous modules (300). The modules (300) can be arranged in a variety of configurations to form neural networks with various topologies, for example, with a hierarchical modular structure. Each module (300) contains sufficient neurons (100) to enable it to do useful work as a stand alone system, with the advantage that many modules (300) can be connected together to create a wide variety of configurations and network sizes. This modular approach results in a scaleable system that meets increased workload with an increase in parallelism and thereby avoids the usually extensive increases in training times associated with unitary implementations.