The brain is not unstructured, but has an architecture. At a small scale the most well known aspect is the way neurones connect to one another, and this is the aspect which is emulated in artificial neural networks. However, there are other small scale structures, such as glial cells and also larger scale structures, such as six layers of the visual cortex and specialised regions such as Broca's area that is crucial for speach.
Used on pages 109, 110, 560