Mechanistic roles of the subthalamic nucleus and internal globus pallidus: evidence from local field potentials and deep brain stimulation
Journal of Translational Neuroscience. 2018, 3 (4): 1-14.
Deep brain stimulation (DBS) has become an effective therapeutic option for neurological and psychiatric disorders such as Parkinson’s disease (PD), dystonia, and obsessive-compulsive disorder. The subthalamic nucleus (STN) and internal globus pallidus (GPi) are by far the most commonly used targets for DBS in the treatment of PD. However, STN/GPi stimulation sometimes causes side effects, including motor fluctuations, cognitive declines, and worse emotional experience, which affect patients’ postoperative quality of life. Recent invasive electrophysiological studies are driven by the desire to better understand the mechanisms of therapeutic actions and side effects of STN/GPi stimulation. These studies investigated the function of the STN and GPi in motor, cognitive and affective processes by recording single-neuron firing patterns during the surgery or local field potentials after the surgery. Here we review the relevant studies to provide an integrative picture of the functional roles of the STN and GPi within the basal ganglia loops for motor, cognition, and emotion. Previous studies suggested that STN and GPi gamma oscillations encode the strength and speed of voluntary movements (execution), whereas beta oscillations reflect the effort and demand of potential movements (preparation). In the cognitive domain, oscillatory beta activity in the STN is involved when people have to stop an inappropriate action or to suppress salient but task-irrelevant information, whereas theta/delta activity is associated with the adjustment of decision thresholds and cost-benefit trade-off. In the affective domain, STN activity in the alpha band may represent the valence and arousal of emotional information.
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