Performance of planar multisite microprobes in recording extracellular single-unit intracortical activity

The microprobes consist of a thin-film electrode array supported by a silicon micromachined substrate and insulated using deposited dielectrics. Microprobes with multiple recording sites spaced from 30 mu m to 200 mu m apart are used to record spontaneous single-unit activity from rat cerebral cortex. Additionally, a theoretical model is used to establish a basis for interpreting the multisite single-unit data. The results suggest that the microprobes (1) couple tightly to the neural tissue with relatively little disturbance to the neural system, (2) facilitate the identification of single units in multiunit records through the use of spatially-separate recording sites, and (3) can be used to detect the cell position in tissue and observe events such as the propagation of electrical activity from the soma to the dendritic tree.