Interfacing a silicon chip to pairs of snail neurons connected by electrical synapses

Future hybrid neuron-semiconductor chips will consist of complex neural net works that are directly interfaced to electronic integrated circuits. They will help us to understand the dynamics of neuronal networks and may lead t o novel computational facilities. Here we report on an elementary step towa rds such neurochips. We designed and fabricated a silicon chip for multiple two-way interfacing, and cultured on it pairs of neurons from the pedal ga nglia of the snail Lymnaea stagnalis. These neurons were joined to each oth er by an electrical synapse, and to the chip by a capacitive stimulator and a recording transistor. We obtained a set of neuroelectronic units with se quential and parallel signal transmission through the neuron-silicon interf ace and the synapse, with a bidirectionally interfaced neuron-pair and with a signal path from the chip through a synaptically connected neuron pair b ack to the chip. The prospects for assembling more involved hybrid networks on the basis of these neuroelectronic units are considered.