A hybrid circuit of a semiconductor chip and synaptically connected neurons was implemented and characterized. Individual nerve cells from the snail Lymnaea stagnalis were immobilized on a silicon chip by microscopic picket fences of polyimide. The cells formed a network with electrical synapses after outgrowth in brain conditioned medium. Pairs of neurons were electronically interfaced for noninvasive stimulation and recording. Voltage pulses were applied to a capacitive stimulator on the chip to excite the attached neuron. Signals were transmitted in the neuronal net and elicited an action potential in a second neuron. The postsynaptic excitation modulated the current of a transistor on the chip. The implementation of the silicon-neuron-neuron-silicon circuit constitutes a proof-of-principle experiment for the development of neuroelectronic systems to be used in studies on neuronal signal processing, neurocomputation and neuroprosthetics.
Fig. 2: Neuron silicon chip. (A) Electronmicrograph of two-way contact with picket fence made of polyimide. Stimulator wings (St) and transistor (S source, D drain, G gate) are marked. Scale bar 20 µm. (B) Electronmicrograph, after fixation, of neuron from the A cluster of the pedal ganglia in Lymnaea stagnalis in a picket fence after three days in culture. Scale bar 20 µm. (C) Micrograph of neuronal cell bodies (dark blobs) in picket fences on a circle of two-way contacts connected by neurites (bright threads) after two days in culture. The fences consist of six pickets in an outer ring and of five pickets in an inner ring where two pickets of adjacent fences are fused to bar like structures. Scale bar 100 µm.
rss
Top
Print