Multiple single-unit recordings from the CNS using thin-film electrode arrays

The feasibility of using thin-film recording arrays (multisite microprobes) to record cortical activity on a long-term basis has been assessed, using an in vitro turtle preparation and the somatosensory cortex of the cat. When chronically implanted, the impedance of most sires remained stable with intermeasurement variability no larger than that reported for other chronically implanted electrodes. Microprobes were much less susceptible to artifact, due to respiration, heart beat, and head movements, than were traditional rigidly mounted metal electrodes. Stable cortical signals were recorded for periods as long as four weeks. Adhering the microprobes to the pia using cyanoacrylate glue appeared to lengthen significantly the longevity of the recordings. It was possible to identify small groups of neurons that responded to a characteristic cutaneous receptive field over time, indicating that the microprobes likely maintain a constant position within the cortex. Using microprobes with multiple recording sites located along a single shank, it was possible to record several units within a single cortical column