The two-volume set LNCS 4527 and LNCS 4528 is the referee Second International Working Conference on the interplay between Natural and Artificial Computation, IWINAC 2007, which was held in La Manga del Mar menor, Spain in June 2007. The 126 revised papers presented are thematically divided into two volumes, the first includes all the contributions mainly related with aspects of theoretical, conceptual and methodological connecting AI and knowledge engineering with neurophysiology, and cognition clinic.