Deep brain implantable microelectrode arrays for detection and functional localization of the subthalamic nucleus in rats with Parkinson's disease

The subthalamic nucleus (STN) is considered the best target for deep brain stimulation treatments of Parkinson's disease (PD). It is difficult to localize the STN due to its small size and deep location. Multichannel microelectrode arrays (MEAs) can rapidly and precisely locate the STN, which is important for precise stimulation. In this paper, 16-channel MEAs modified with multiwalled carbon nanotube/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (MWCNT/PEDOT:PSS) nanocomposites were designed and fabricated, and the accurate and rapid identification of the STN in PD rats was performed using detection sites distributed at different brain depths. These results showed that nuclei in 6-hydroxydopamine hydrobromide (6-OHDA)-lesioned brains discharged more intensely than those in unlesioned brains. In addition, the MEA simultaneously acquired neural signals from both the STN and the upper or lower boundary nuclei of the STN. Moreover, higher values of spike firing rate, spike amplitude, local field potential (LFP) power, and beta oscillations were detected in the STN of the 6-OHDA-lesioned brain, and may therefore be biomarkers of STN localization. Compared with the STNs of unlesioned brains, the power spectral density of spikes and LFPs synchronously decreased in the delta band and increased in the beta band of 6-OHDA-lesioned brains. This may be a cause of sleep and motor disorders associated with PD. Overall, this work describes a new cellular-level localization and detection method and provides a tool for future studies of deep brain nuclei.