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

Brain Stimul. May-Jun 2018;11(3):607-617. doi: 10.1016/j.brs.2018.01.028. Epub 2018 Jan 31.

Abstract

Objective: 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.

Methods: 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.

Results: 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).

Conclusions: 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.

Keywords: Deep brain stimulation; Globus pallidus internus; Motor cortex; Parkinson disease; Phase amplitude coupling.

Publication types

  • Clinical Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Beta Rhythm / physiology*
  • Cerebral Cortex / physiology*
  • Deep Brain Stimulation*
  • Electrocorticography
  • Female
  • Gamma Rhythm / physiology*
  • Globus Pallidus / physiology*
  • Humans
  • Male
  • Middle Aged
  • Models, Neurological
  • Movement / physiology
  • Parkinson Disease / therapy*