Pallidal deep brain stimulation modulates excessive cortical high β phase amplitude coupling in Parkinson disease

• Published in: Brain stimulation 2018-05, Vol.11 (3), p.607-617
• Main Authors: Malekmohammadi, Mahsa, AuYong, Nicholas, Ricks-Oddie, Joni, Bordelon, Yvette, Pouratian, Nader
• Format: Article
• Language: English
• Subjects: Aged; Beta Rhythm - physiology; Cerebral Cortex - physiology; Deep Brain Stimulation; Electrocorticography; Female; Gamma Rhythm - physiology; Globus Pallidus - physiology; Globus pallidus internus; Humans; Male; Middle Aged; Models, Neurological; Motor cortex; Movement - physiology; Parkinson disease; Parkinson Disease - therapy; Phase amplitude coupling
• ISSN: 1935-861X; 1876-4754
• DOI: 10.1016/j.brs.2018.01.028

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) and globus pallidus internus (GPi) are equally efficacious in the management of Parkinson disease (PD). Studies of STN-DBS have revealed a therapeutic reduction in excessive cortical β-γ phase-amplitude coupling (PAC). It is unclear whether this is specific to STN-DBS and potentially mediated by modulation of the hyperdirect pathway or if it is a generalizable mechanism seen with DBS of other targets. Moreover, it remains unclear how cortical signals are differentially modulated by movement versus therapy. To clarify, the effects of GPi-DBS and movement on cortical β power and β-γ PAC were examined. Right sensorimotor electrocorticographic signals were recorded in 10 PD patients undergoing GPi-DBS implantation surgery. We evaluated cortical β power and β-γ PAC during blocks of rest and contralateral hand movement (finger tapping) with GPi-DBS off and on. Movement suppressed cortical low β power (P = 0.008) and high β-γ PAC (P = 0.028). Linear mixed effect modeling (LMEM) showed that power in low and high β bands are differentially modulated by movement (P = 0.022). GPi-DBS also results in a significant suppression of high β-γ PAC but without power modulation in either β sub-band (P = 0.008). Cortical high β-γ PAC is significantly correlated with severity of bradykinesia (Rho = 0.59, P = 0.045) and changes proportionally with therapeutic improvement (Rho = 0.61, P = 0.04). Similar to STN-DBS, GPi-DBS reduces motor cortical β-γ PAC, like that also reported with dopaminergic mediations, suggesting it is a generalizable symptom biomarker in PD, independent of therapeutic target or proximity to the hyperdirect pathway. •GPi-DBS modulates motor cortical signals similar to the STN-DBS.•Movement suppresses low β power and high β-γ PAC in motor cortex.•GPi-DBS suppresses motor cortical high β-γ PAC without changes in cortical β power.•Motor cortical high β-γ PAC correlates with the severity of bradykinesia.•GPi-DBS reduces high β-γ PAC proportionally to the improvement in bradykinesia.