This book is a collection of selected papers from the 21st edition of the WIRN workshop.

Along with the regular sessions, the annual meeting of the Italian Neural Networks Society (SIREN) customarily includes special sessions where conference participants discuss and analyze the latest challenges in the field of neural networks and related topics. Similarly, in the tradition of the workshop, the open-minded and friendly style of the discussions attract the contribution of researchers from many different countries, as well as a solid community of historical members who have grown the society through its 21 years.

All the authors have presented original results, and peer reviewers worked generously to enhance the texts by suggesting improvements and remedying possible lapses.

As for the content; the regular session papers are divided as usual into three groups: Applications, Models and specific Signal Processing implementations. Then come the contributions to the following special sessions: Autonomous Machine Learning, Neuromorphic Engineering and Models of Behavior for Human-Machine Interaction. The first special session was organized in cooperation with INNS SIG AML (International Neural Networks Society – Special Interest Groups on Autonomous Machine Learning); the last constitutes a special activity of the European COST (European Cooperation in Science and Technology) Action 2012 on Cross-Modal Analysis of Verbal and Nonverbal Communication.

The Editors would like to take this opportunity to thank the invited speakers and contributors as well as the referees for their efforts in the realization of this volume, and look forward to meeting them all again next year.