This chapter deals with neural networks using Neural Networks Toolbox built into the MATLAB® software to address a particular problem. The major goal is to become familiar with the general concept of unsupervised neural networks and how they may relate to certain forms of synaptic plasticity in the nervous system. Neural networks have assumed a central role in a variety of fields. They are actually quite abstract computing structures. In fact, they are sometimes referred to as artificial neural networks. The nature of this role is fundamentally dualistic. On the one hand, neural networks can provide powerful models of elementary processes in the brain, including processes of plasticity and learning. On the other hand, they provide solutions to a broad range of specific problems in applied engineering, such as speech recognition, financial forecasting, or object classification.