Miniature microdrive for extracellular recording of neuronal activity in freely moving animals.

The new design of a removable miniature microdrive for extracellular recordings of single-unit activity in freely moving animals with high-impedance electrodes is presented. The construction permits very simple installation and removal of the microelectrodes, rapid fixation of the microdrive on the animals skull and rapid removal after recording. The microdrive provides vertical positioning of the electrode without rotations and lateral shifts, stable recordings of single units for several hours and the possibility to change the penetration track 20-30 times in the same animal. The 3.2-mm diameter of the microdrive cylinder permits the installation of several units simultaneously. The weight of the microdrive with the base is 115 mg. The microdrive permits penetrations to any desired depth.