**R. A. Legenstein and W. Maass**

We introduce *total wire length* as salient complexity measure for an
analysis of the circuit complexity of sensory processing in biological neural
systems and neuromorphic engineering. Furthermore we introduce a set of basic
computational problems that apparently need to be solved by circuits for
translation- and scale-invariant sensory processing. Finally we exhibit a
number of circuit design strategies for these new benchmark functions that
can be implemented within realistic complexity bounds, in particular with
linear or almost linear total wire length.