kilian@poplar.cray.com (Alan Kilian) (06/25/91)
This is about as leading edge as it gets but I thought some of you might be interested. In _Science_ 31-May-1991 the following article appeared: Pp1227 Neuron-silicon junction. The goal of developing neural biosensors and various forms of neuroelectronic circuitry is now somewhat closer: a tight electronic junction has been successfully formed between a nerve cell and silicon (Page 1290). Fromherz et al. dissociated individual neurons (called Retzius cells) from segmental ganglions of leeches and connected them to oxidized silicon; the junction behaved like a field-effect transistor. Both spontaneous and induced signals were recorded and were found to resemble typical electrical discharges -action potentials- of firing neurons. The attachment of neuron and silicon, which occurs through the plasma membrane and the gate oxide of the silicon, is intimate, allowing for electrical transmission by the junction. If this single neuron technology can be applied to neurons in networks, it should facilitate analyses of complex neural systems. PP1290 A Neuron-Silicon Junction: A Retzius Cell of the Leech on an Insulated-Gate Field-Effect Transistor. Peter Fromherz, Andreas Offenhaeusser, Thomas Vetter, Juergen Weis An identified neuron of the leech, a Retzius cell, has been attached to the open gate of a p-channel field-effect transistor. Action potentials, spontaneous or stimulated, modulate directly the source-drain current in silicon. The electronic signals match the shape of the action potential. The average voltage on the gate was up to 25% of the intracellular voltage change. Occasionally weak signals that resemble the first derivative of the action potential were observed. The junction can be described by a model that includes capacitive coupling of the plasma membrane and the gate oxide and that accounts for the variable resistance of the seal. What this says is that they plucked a single neuron and its dendrites and plopped it down on a piece of silicon and could stimulate the dendrites and record the cells activity. Very impressive and also very far from a direct neural connection for VR. -Alan Kilian kilian@cray.com 612.683.5499 Cray Research, Inc. | "If the human brain was so simple that we 655 F Lone Oak Drive | could understand it, we would be so simple Eagan MN, 55121 | that we couldn't". -Pugh (Whoever that is)