Electrode Position and Current Amplitude Modulate Impulsivity after Subthalamic Stimulation in Parkinsons Disease-A...

Area of Science:

• Computational neuroscience
• Neurobiology of decision-making
• Parkinson's disease research

Background:

• Subthalamic Nucleus Deep Brain Stimulation (STN-DBS) effectively manages Parkinson's disease (PD) motor symptoms.
• STN-DBS is associated with increased impulsivity and impulse control disorders (ICDs).

Purpose of the Study:

• To compare decision-making performance on the Iowa Gambling Task (IGT) in healthy controls (HC), untreated PD, and medically-treated PD with and without STN stimulation.
• To investigate if electrode position and stimulation current modulate impulsivity following STN-DBS.

Main Methods:

• Developed a computational spiking network model of the basal ganglia (BG) to simulate STN activity in PD.
• Applied reinforcement learning to model IGT performance under varying dopaminergic and STN stimulation conditions.
• Compared IGT total and bin scores across different simulated conditions.

Main Results:

• The computational model accurately replicated neural activity in normal and PD states.
• PD patients (untreated and treated) exhibited higher impulsivity (lower IGT scores) than HC (P < 0.0001).
• Specific electrode placements and supratherapeutic stimulation amplitudes worsened IGT performance (P < 0.0001 and P < 0.001, respectively).

Conclusions:

• STN stimulation in a computational model of PD led to impulsive decision-making on the IGT.
• Electrode position and stimulation current are critical factors influencing impulsivity in STN-DBS.
• These findings may explain the variability in STN-DBS effects observed in PD patients.