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Since the advent of deep brain stimulation (DBS) for the treatment of Parkinson's disease (PD), subsequent cognitive and neuropsychiatric effects of this procedure have become well-chronicled. Yet, thermolitic lesion of the subthalamic nucleus (STN) is still a valid option when DBS cannot be applied, and little has been published regarding its impact on cognition and mood. We examined the cognitive and neuropsychiatric functions of 10 consecutive patients with advanced PD undergoing simultaneous bilateral subthalamotomies. With 24 months of follow-up, the patients, three of whom were on anticholinergics prior to surgery, showed no deterioration in cognitive assessments including verbal fluency. Hypoactive behaviors (depression and apathy) showed lasting improvement, while hyperactive behaviors (euphoria and disinhibition) transiently increased after surgery. Improvement in hypoactive behaviors correlated with improvement in hypokinetic movements, and enhanced hyperactive behaviors followed the course of post-operative hyperkinetic movements. Such correlations may support the role of the STN in modulating limbic connections between the basal ganglia and frontal cortex. The results of this proof-of-concept pilot study suggest the need for larger, long-term, randomized controlled studies to assess motor, neuropsychiatric, behavioral and radiologic correlations after subthalamotomies. [ABSTRACT FROM AUTHOR]

Abstract: Objective: The observation of a voluntary movement executed by another person is associated with an alpha and beta EEG desynchronization over the motor cortex, thought to reflect activity from the human “mirror neuron” system. The aim of our work was to study the changes in local field potentials (LFP) recorded from the subthalamic nucleus (STN) and their relationship with cortical activity, during movement observation. Methods: Bilateral EEG and STN LFP recordings were acquired in 18 patients with Parkinson’s disease, through surgically implanted electrodes for deep brain stimulation. Oscillatory changes during movement execution and movement observation were compared with two different control conditions (simple stimulus and rotating stimulus observation), in “off” and “on” motor states. Time–frequency transforms and event-related coherence were used for the analysis. Results: Movement observation was accompanied by bilateral beta reduction in subthalamic power and cortico-STN coherence, which was smaller than the decrease observed during movement execution, but significant when compared with the two control conditions. Conclusions: Movement observation is accompanied by changes in the beta oscillatory activity of the STN, similar to those observed in the EEG. Significance: These changes suggest that the basal ganglia might be engaged by the activity of the human mirror system. [Copyright &y& Elsevier]