Towards artificial neurons and synapses: a materials point of view
We overview several efforts to emulate functionalities of basic building blocks, i.e. neurons and synapses, of a mammal’s brain by means of non-biological inorganic systems. These efforts have been put to realize ambitious goals such as the achievement of artificial inorganic brains on silicon wafers, i.e. neuromorphic systems, and neuroprosthetic systems taking part in real brain functionalities by interfacing with real brains. In terms of the keywords, ‘threshold’, ‘analogue’, ‘plasticity’, and ‘elasticity’, which describe the behaviour of neurons and synapses, various functional systems, with particular emphasis on nanoionic systems, exhibiting these key behaviours, are dealt with in this review.