Modulation of Beta Oscillations in the Subthalamic Nucleus with Prosaccades and Antisaccades in Parkinson's Disease

Abstract

Increased oscillations in the beta band are thought to be related to motor symptoms of Parkinson's disease (PD). Previous studies haveshown that beta-band desynchronization in the subthalamic nucleus (STN) is reduced just before and during limb movements. While the STN is part of the basal ganglia (BG)-thalamocortical circuit controlling limb movements, it is also part of the BG-brainstem projection controlling saccadic eye movements. Late-stage PD patients have deficits in saccades in addition to difficulties with limb movements arising from impaired functions of the BG. We investigated saccade-related changes in beta-band (15-30 Hz) oscillatory activities in the human STN while PD patients performed visually guided prosaccades and antisaccades, the latter requiring suppression of reflexive responses and volitional initiation of saccades. We recorded local field potentials from deep brain stimulation electrodes implanted in the STN in human PD patients 1-5 d after surgery and compared prosaccades and antisaccades with these and with limb movements. Saccade-related beta-band desynchronizations were observed just before and during saccades in all subjects, suggesting that reduction of beta-band oscillatory activity in the STN is related to preparation and execution of saccades. Furthermore, beta-band desynchronizations for antisaccades started earlier, were sustained for longer periods, were of greater magnitude, and were observed more often than prosaccades. Beta-band desynchronization in the STN may reflect the additional processes associated with suppression of reflexive responses and volitional execution of saccades in the opposite direction.

Subthalamic nucleus local field potentials recordings reveal subtle effects of promised reward during conflict resolution in Parkinson’s disease

“…So far, whether beta suppression or enhancement is involved in inhibition is still a matter of debate (see Zavala et al, 2015). However, one could interpret our results in line with Yugeta et al (2013), claiming that stronger beta suppression in 5…”

Effects of Deep Brain Stimulation on Eye Movements and Vestibular Function

“…The STN not only facilitates saccades, but also plays a critical role in their planning. Recordings of local field potentials from STN DBS electrodes show event related desynchronizations in the beta band immediately prior to saccades ( 48 ) that are qualitatively similar to those seen in motor planning of limb movement.…”

Antisaccades in Parkinson’s Disease: A Meta-Analysis

“…(Jahanshahi et al, 2015) In a study of local field potentials in the STN of patients with PD during DBS surgery, saccade-related beta band desynchronization during preparation of an antisaccade was stronger and longer preceding the execution of a correct antisaccade than an error. (Yugeta et al, 2013) While suppression of pathologically enhanced synchronization of beta oscillations in the sensorimotor circuits between cortex, basal ganglia and thalamus is thought to lead to the improvement of bradykinesia with STN-DBS (Little et al, 2013), the same mechanism may also result in increased motor impulsivity via the hyperdirect pathway. (Jahanshahi, 2013) Whether different locations of the DBS electrodes within STN as well as other DBS targets, such as GPi, may result in variable effects on antisaccade performance, should be investigated in future research.…”