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

Background: 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. 

Methods: Data from fourteen intraoperative microelectrode recordings (MERs) of STN in PD patients were divided into 500 ms bins. Beta (14-30 Hz), low gamma (30-80 Hz), high gamma (80-200 Hz), and broadband (2-200 Hz) powers were compared to the spiking band (300-3000 Hz) power for each bin at each recording depth corresponding to the STN. The recording depths corresponding to the upper one-third and lower one-third STN were defined as the dorsal and ventral STN segments, respectively. Correlation coefficients between each band and spiking band powers for the dorsal and ventral STN segments were assessed for differences in either significance (p <0.05) or directionality. 
 

Results: Correlations in beta and spiking band powers were different between the dorsal and ventral STN for eleven STNs. Correlations in low gamma and spiking band powers were different between the dorsal and ventral STN for eight STNs. Correlations in high gamma and spiking band powers were different between the dorsal and ventral STN for four STNs. Correlations in broadband and spiking band powers were different between the dorsal and ventral STN for five STNs. 

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