Pd has already an external collection called ann, which has support for feedforward networks and a basic self organizing map (SOM).

The goal of this project would be to extend the Pd bindings to the Fast Artificial Neural Network library (FANN) and include new FANN features like self organizing maps, growing neural gas and more.

Thread about these features:

• in the FANN forum: http://leenissen.dk/fann/forum/viewtopic.php?t=46&start=30
• in pd-list: pd-list@iem.at/msg16138.html">http://www.mail-archive.com/pd-list@iem.at/msg16138.html

Also bindings to other libraries which support recurrent neural networks should be considered.