The cone electrode: a long-term electrode that records from neurites grown onto its recording surface.

A novel long-term recording electrode combines neural regeneration with a standard wire recording technique. The electrode consists of an insulated gold wire fixed inside a hollow glass cone. A piece of sciatic nerve is placed in the glass cone before implantation in cortex of rat. Cortical neurites grow into the sciatic nerve in the cone from surrounding neurons and their electrical activity is recorded via the wire (or wires) in the cone. This activity increases in amplitude over the first few weeks after implantation and remains stable until termination of the experiment many months later. Activity of both single and multi units has been recorded. The cone electrode opens unique opportunities for studies of neurite growth in vivo, for plasticity studies on a captive set of neurites, for studying the neural correlates of behavior and motor learning, and for accessing the central nervous systems of patients with severe paralysing and communicative disorders.