A sequence of papers have been recently published, pointing out various
intractable problems which may be solved in certain fashions within the framework of
spiking neural (SN) P systems. On the other hand, there are also results demonstrating
limitations of SN P systems. In this paper we define recognizer SN P systems providing a
general platform for this type of results. We intend to give a more systematic characterization
of computational power of variants of SN P systems, and establish their relation
to standard complexity classes