To identify neurophysiologic biomarkers that characterize dorsal and ventral subthalamic nucleus (STN) in Parkinson’s disease (PD) patients.

Deep brain stimulation (DBS) of the STN is a well-established therapy for the motor symptoms of PD. Anatomically, the STN can be divided into a dorsal sensorimotor region and a ventral limbic and associative region. Clinically, it is desired to stimulate the motor region to maximize motor benefit and minimize limbic side effects. However, this is not always practically possible, as the boundary between dorsal and ventral STN is not always well defined. While previous primate and human studies have differentiated dorsal and ventral STN anatomically, there is a relative paucity of data regarding the neurophysiologic biomarkers of ventral versus dorsal STN in PD patients. These biomarkers can serve as a guide for optimal intraoperative electrode placement and postoperative programming.   

Data from fifteen intraoperative microelectrode recordings (MERs) of STN in PD patients will be analyzed. Intraoperative microelectrode recordings during the localization segment of the surgery will be divided into 500 ms bins. Broadband (2-200 Hz) and spiking band (300-3000 Hz) powers will be computed for each bin at each recording depth corresponding to the STN. Two of the fifteen recordings have been analyzed so far.

For one recording, beta-band (14-30 Hz) and spiking band powers (SBP) were positively correlated (p < 0.01) in the ventral STN but were not correlated (p > 0.05) in the dorsal STN. For another recording, broadband, low gamma-band (30-80 Hz), high gamma-band (80-200 Hz), and beta-band powers were all negatively correlated with SBP (p < 0.01) in the ventral STN, but were positively correlated with SBP (p < 0.05) in the dorsal STN.

The dorsal and ventral STN have unique electrophysiologic fingerprints that allow them to be distinguished using intraoperative MERs.