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Abstract: One type of future, improved neural interface is the "cultured probe". It is a hybrid type of neural information transducer or prosthesis, for stimulation and/or recording of neural activity. It would consist of a microelectrode array (MEA) on a planar substrate, each electrode being covered and surrounded by a local circularly confined network ("island") of cultured neurons. The main purpose of the local networks is that they act as biofriendly intermediates for collateral sprouts from the in vivo system, thus allowing for an effective and selective neuron-electrode interface. As a secondary purpose, one may envisage future information processing applications of these intermediary networks. In this paper, first, progress is shown on how substrates can be chemically modified to confine developing networks, cultured from dissociated rat cortex cells, to "islands" surrounding an electrode site. Additional coating of neurophobic, polyimide-coated substrate by triblock-copolymer coating enhances neurophilic-neurophobic adhesion contrast. Secondly, results are given on neuronal activity in patterned, unconnected and connected, circular "island" networks. For connected islands, the larger the island diameter (50, 100 or 150 µm), the more spontaneous activity is seen. Also, activity may show a very high degree of synchronization between two islands. For unconnected islands, activity may start at 22 days in vitro (DIV), which is two weeks later than in unpatterned networks.
Key words: Cultured neuronal networks, network patterning, network activity, MEA, multi electrode array, neurophilic/neurophobic substrate coating, neuronal synchronization.
(ProQuest Information and Learning: ... denotes formula omitted.)
INTRODUCTION
Efficient and selective electrical stimulation and recording of neural activity in peripheral, spinal or central neural pathways requires multielectrode arrays at micrometer or nanometer scale. At present, wire arrays in brain, flexible linear arrays in the cochlea and cuff arrays around nerve trunks are in experimental and/or clinical use. Two- and three-dimensional brush-like microarrays and "sieves", with around hundred electrode sites, have been proposed, fabricated in microtechnology and/or tested in a number of laboratories.
As there are no "blueprints" for the exact positions of fibers in a peripheral nerve, or motor neurons in a ventral root region, an insertablemultielectrode has to be designed in a redundant way. Even then, the efficiency of a multi-electrode will be less than 100%, as not every electrode will contact one neural axon or soma.
Therefore, "cultured...