  Objective. Exploring neural activity behind synchronization and time locking
in brain circuits is one of the most important tasks in neuroscience. Our goal
was to design and characterize a microelectrode array (MEA) system specifically
for obtaining in vivo extracellular recordings from three deep-brain areas of
freely moving rats, simultaneously. The target areas, the deep mesencephalic
reticular-, pedunculopontine tegmental- and pontine reticular nuclei are
related to the regulation of sleep-wake cycles. Approach. The three targeted
nuclei are collinear, therefore a single-shank MEA was designed in order to
contact them. The silicon-based device was equipped with 3*4 recording sites,
located according to the geometry of the brain regions. Furthermore, a
microdrive was developed to allow fine actuation and post-implantation
relocation of the probe. The probe was attached to a rigid printed circuit
board, which was fastened to the microdrive. A flexible cable was designed in
order to provide not only electronic connection between the probe and the
amplifier system, but sufficient freedom for the movements of the probe as
well. Main results. The microdrive was stable enough to allow precise electrode
targeting into the tissue via a single track. The microelectrodes on the probe
were suitable for recording neural activity from the three targeted brainstem
areas. Significance. The system offers a robust solution to provide long-term
interface between an array of precisely defined microelectrodes and deep-brain
areas of a behaving rodent. The microdrive allowed us to fine-tune the probe
location and easily scan through the regions of interest.
