Theta-frequency subthalamic nucleus stimulation increases decision threshold.

Introduction: Executive functions are often impaired in patients with Parkinson's disease (PD), and these deficits can be predicted by decreased frontal cortical 4-8 Hz theta activity that is associated with cognitive control. Previous work has shown that stimulating the subthalamic nucleus (STN) at theta frequencies via deep-brain stimulation (DBS) can improve cognitive control. Here we tested the neurocomputational hypothesis that stimulating STN theta activity increases decision thresholds, supporting more deliberate responding and nuanced adaptation under task trials that require cognitive control.

Methods: We tested 15 patients with PD receiving STN DBS at standard therapeutic frequencies ∼130 Hz and at 4 Hz while performing a Simon reaction-time task and applying computational diffusion decision modeling analyses to quantify the latent cognitive characteristic of response cautiousness via the well-established model parameter known as the decision threshold. This computational analyses better accounts for the speed-accuracy trade off when making deliberate choices.

Results: We found that ∼130-Hz STN DBS decreased decision thresholds in line with our prior work, and we report new results showing that 4-Hz STN DBS increased decision thresholds.

Conclusions: These findings extend our knowledge of how the STN controls decision thresholds. Future work will study the STN's role in motor and cognitive control and how stimulating this region may modulate cognition in PD.