A new article on New scientist features Spikey, the new chip coming out of Karlheinz Meier's group. The University of Heidelberg, Germany, chip contains contains 400 "neurons". The original article (see link) describes the various networks the group was able to implement in the chip, which includes a variety of different circuits.
from the article:
Attempts to simulate the brain usually involve programming software to behave like groups of neurons. A new "neuromorphic" design instead tries to recreate the brain's hardware, using analogue components last seen in the early days of computing. "On our system, you can physically point to the neuron," says Karlheinz Meier of the University of Heidelberg in Germany.
Read more: http://www.newscientist.com/article/mg21628925.100-brainlike-chip-outstrips-normal-computers.html