Microdrive and method for single unit recording in the active rat

A technique for recording single unit activity in the active rat with microelectrodes is described. The microdrive used is small and light enough to be carried in a well that is chronically implanted on the head of the rat. The device permits standard microelectrodes to be lowered without rotation, a feature which reduces chance of damage to the fine tips and to the brain tissue. The microdrive itself may be rotated in the well and several penetrations in a single preparation are possible. The electrodes used are capable of recording unit activity of high amplitude and stability. Units may be held for minutes or hours depending on the intensity of the rat's behavior.