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We report on the recording of electrical activity in cultured hippocampal slices by a multitransistor array (MTA) with 16,384 elements. Time-resolved imaging is achieved with a resolution of 7.8 microm on an area of 1 mm2 at 2 kHz. A read-out of fewer elements allows an enhanced time resolution. Individual transistor signals are caused by local evoked field potentials. They agree with micropipette measurements in amplitude and shape. The spatial continuity of the records provides time-resolved images of evoked field potentials and allows the detection of functional correlations over large distances. As examples, fast propagating waves of presynaptic action potentials are recorded as well as patterns of excitatory postsynaptic potentials across and along cornu ammonis.

The electrical activity of a network of mammalian neurons is mapped with a Multi-Transistor Array (MTA) fabricated with extended CMOS technology. The spatial resolution is 7.4 µm on an area of 1 mm 2 at a sampling frequency of 6 kHz for a complete readout of 16,384 sensor transistors. Action potentials give rise to extracellular voltages with amplitudes in a range of 500 µV. On the basis of the high resolution in space and time, correlation algorithms are used to identify single action potentials with amplitudes as low as about 200µV, and to assign the signals to the activity of individual neurons even in a dense network.

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