Parkinson’s disease (PD) is a neurological disorder caused by progressive loss of dopaminergic neurons in the basal ganglia and characterized by tremor, movement difficulty, and muscle stiffness. PD affects 1% individual age over 60 years. Drug supplementation therapy compensates reduced dopamine and successfully treats PD symptoms. However, drug control of symptoms becomes difficult after a few years. For advanced PD, deep brain stimulation (DBS), applying electric stimulation to the subthalamic nucleus (STN), improves symptoms but associated with reduced efficacy with time and higher battery consumption. These problems prompted for a more efficient stimulation method.
In the team’s previous study, in PD monkeys, the movement signals originating from the primary motor cortex (M1) were blocked in the internal segment of the globus pallidus (GPi), causing movement difficulty. Manipulation of the STN unblocked the GPi and recovered movements. Therefore, the team speculated that controlling the DBS by the M1 activity might be a better treatment option for PD.
In this research, DBS was applied to the STN of the PD model monkeys. At first, the research team investigated the movement-related activity in the M1 and found that γ2 band (80-200 Hz) activity is a suitable biomarker for movements in PD condition. After that, recovery of upper limb reaching task was studied by applying DBS to the STN. They observed that the monkey could only reach out slowly without DBS whereas the application of conventional DBS with constant strength and frequency (cDBS) enabled smooth movement. Then, they controlled the strength and frequency of DBS by M1-γ2 activity and observed that this method, adaptive DBS (aDBS), enabled similarly smoother task. Moreover, aDBS battery consumption is 2/3 of the cDBS.
These results indicate that the newly developed aDBS enables modulation of stimulation parameters of STN-DBS in response to M1-γ2 band activity and is an extremely efficient treatment method in PD monkeys. In conclusion, M1-γ2 aDBS is an effective therapeutic approach which has a possible clinical application in PD patients and is expected to contribute to better DBS.
Scientific Reports
Experimental study
Animals
Subthalamic nucleus deep brain stimulation driven by primary motor cortex γ2 activity in parkinsonian monkeys
20-Apr-2022