Effective deep brain stimulation for obsessive-compulsive disorder and Tourette Syndrome increases network-wide...

Area of Science:

• Neuroscience
• Neuromodulation
• Computational Psychiatry

Background:

• Deep brain stimulation (DBS) is a proven therapy for obsessive-compulsive disorder (OCD) and Tourette syndrome (TS).
• Previous research indicated disrupted circadian periodicity and heightened neural variability in the ventral striatum (VS) of DBS responders for OCD.
• The current study investigates if this link between neural variability and symptom improvement extends beyond the VS to the globus pallidus internus (GPi).

Purpose of the Study:

• To test if increased neural variability in the globus pallidus internus (GPi) predicts symptom improvement in patients with Tourette syndrome (TS).
• To determine if the relationship between neural variability and symptom improvement observed in the ventral striatum (VS) for obsessive-compulsive disorder (OCD) generalizes to the GPi for TS.

Main Methods:

• Chronic local field potential (LFP) recordings were obtained from four patients with OCD and comorbid TS undergoing DBS in both the VS and GPi.
• Spectral power in the 9 Hz band was measured continuously for over 900 days.
• Neural variability was estimated using an autoregressive model applied to the neural power time series.

Main Results:

• In all four patients, neural variability in both the VS (for OCD) and GPi (for TS) accurately classified responder status.
• Two patients achieved responder status for both OCD and TS.
• Cross-correlation and Granger causality analyses revealed distinct lead-lag intervals and directionality between the VS and GPi, indicating unique information content.

Conclusions:

• Increased low-frequency neural variability in the VS and GPi predicts symptom improvement in OCD and TS, respectively.
• These findings support and extend previous observations in OCD, reinforcing the principle that optimal physiological variability is crucial for effective biological system function.
• The results suggest that neural variability in basal ganglia targets is a significant biomarker for DBS treatment efficacy in movement and behavioral disorders.