I. Introduction
Human brain has some inherent advantages over the current processors. It can generalise information, interpret information in noisy environment, learn from and adapt to its environment while being very robust and consuming just 20 watts of power. Thus, it has been a source of inspiration for researchers trying to optimize processor design. In this endeavor, several digital versions of the brain like the IBM's simulation of mouse brain on Blue Gene have been conceived. However, this digital implementation requires about 40 KW of power and sizable hardware.