. Author manuscript; available in PMC: 2020 Apr 1.

Published in final edited form as: Clin Neurophysiol. 2018 Nov 30;130(4):558–567. doi: 10.1016/j.clinph.2018.10.020

Table 1.

Changes in motor cortical excitability and cortical circuits with deep brain stimulation

Measurements	Parkinson’s disease STN		Parkinson’s disease GPi		Dystonia GPi
Measurements	OFF	ON	OFF	ON	OFF	ON
MEP threshold	↔	↔	↔	↔	↔	↔
MEP amplitude	↑	↑	↑	↑	↓^a	↔^a
SICI	↓	Normalized	↓	↓	↓	Normalized
ICF	↔	↔	↔	↔	↔	↔
LICI	↔	↔	↑^b	Normalized^b	Not tested	Not tested

Abbreviations

GPi = internal globus pallidus, ICF = intracortical facilitation, LICI = long interval intracortical inhibition, MEP = motor evoked potential, SICI = short interval intracortical inhibition, STN = subthalamic nucleus, ↑ = increase, ↓ = decrease, ↔ = no change.

All changes are based on the comparison between patients (Parkinson’s disease patients with STN and GPi deep brain stimulation and dystonia patients with GPi stimulation) and healthy controls.

ON refers to the state that deep brain stimulation was turned on with the clinical setting and OFF refers to the state that the stimulation was turned off.

Normalized refers to the effect that deep brain stimulation normalized the abnormality in the patients when the stimulation was turned off.

Notes:

^a.

MEP amplitude in dystonia patients with GPi deep brain stimulation does not change even after the stimulation has been turned on for 6 months. However, switching off the stimulator may lead to a transient reduction in the slope of MEP recruitment curve.

^b.

Tested with cortical silent period in the active state with voluntary muscle contraction.