Real-time multisite invasive neural recording during downhill skiing in Parkinson’s disease: a case report

To determine placement of electrodes after deep brain stimulation (DBS) surgery, a novel toolbox that facilitates both reconstruction of the lead electrode trajectory and the contact placement is introduced. Using the toolbox, electrode placement can be reconstructed and visualized based on the electrode-induced artifacts on post-operative magnetic resonance (MR) or computed tomography (CT) images. Correct electrode placement is essential for efficacious treatment with DBS. Post-operative knowledge about the placement of DBS electrode contacts and trajectories is a promising tool for clinical evaluation of DBS effects and adverse effects. It may help clinicians in identifying the best stimulation contacts based on anatomical target areas and may even shorten test stimulation protocols in the future. Fifty patients that underwent DBS surgery were analyzed in this study. After normalizing the post-operative MR/CT volumes into standard Montreal Neurological Institute (MNI)-stereotactic space, electrode leads (n=104) were detected by a novel algorithm that iteratively thresholds each axial slice and isolates the centroids of the electrode artifacts within the MR/CT-images (MR only n=32, CT only n=10, MR and CT n=8). Two patients received four, the others received two quadripolar DBS leads bilaterally, summing up to a total of 120 lead localizations. In a second reconstruction step, electrode contacts along the lead trajectories were reconstructed by using templates of electrode tips that had been manually created beforehand. Reconstructions that were made by the algorithm were finally compared to manual surveys of contact localizations. The algorithm was able to robustly accomplish lead reconstructions in an automated manner in 98% of electrodes and contact reconstructions in 69% of electrodes. Using additional subsequent manual refinement of the reconstructed contact positions, 118 of 120 electrode lead and contact reconstructions could be localized using the toolbox. Taken together, the toolbox presented here allows for a precise and fast reconstruction of DBS contacts by proposing a semi-automated procedure. Reconstruction results can be directly exported to two- and three-dimensional views that show the relationship between DBS contacts and anatomical target regions. The toolbox is made available to the public in form of an open-source MATLAB repository.

It has been shown in animals that neuronal activity in the 'gamma band' (>30 Hz) is associated with cortical activation and may play a role in multi-regional and multi-modal integration of cortical processing. Studies of gamma activity in human scalp EEG have typically focused on event-related synchronization (ERS) in the 40 Hz band. To assess further the gamma band ERS further, as an index of cortical activation and as a tool for human functional brain mapping, we recorded subdural electrocorticographic (ECoG) signals in five clinical subjects while they performed visual-motor decision tasks designed to activate the representations of different body parts in sensorimotor cortex. ECoG spectral analysis utilized a mixed-effects analysis of variance model in which within-trial temporal dependencies were accounted for. Taking an exploratory approach, we studied gamma ERS in 10-Hz-wide bands (overlapping by 5 Hz) ranging from 30 to 100 Hz, and compared these findings with changes in the alpha (8-13 Hz) and beta (15-25 Hz) bands. Gamma ERS (observed in three out of subjects) occurred in two broad bands-'low gamma' included the 35-45 and 40-50 Hz bands, and 'high gamma' the 75-85, 80-90, 85-95 and 90-100 Hz bands. The temporal and spatial characteristics of low and high gamma ERS were distinct, suggesting relatively independent neurophysiological mechanisms. Low gamma ERS often began after onset of the motor response and was sustained through much of it, in parallel with event-related desynchronization (ERD) in the alpha band. High gamma ERS often began during, or slightly before, the motor response and was transient, ending well before completion of the motor response. These temporal differences in low and high gamma suggest different functional associations with motor performance. Compared with alpha and beta ERD, the topographical patterns of low and high gamma ERS were more discrete and somatotopically specific and only occurred over contralateral sensorimotor cortex during unilateral limb movements (alpha and beta ERD were also observed ipsilaterally). Maps of sensorimotor function inferred from gamma ERS were consistent with maps generated by cortical electrical stimulation for clinical purposes. In addition, different task conditions in one subject produced consistent differences in both motor response latencies and onset latency of gamma ERS, particularly high gamma ERS. Compared with alpha and beta ERD, the topography of gamma ERS is more consistent with traditional maps of sensorimotor functional anatomy. In addition, gamma ERS may provide complementary information about cortical neurophysiology that is useful for mapping brain function in humans.

Neural recordings in humans using invasive devices can elucidate the circuits underlying brain disorders, but have so far been limited to short recordings from externalized brain leads in a hospital setting or from implanted sensing devices that provide only intermittent, brief streaming of time series data. Here we report the use of an implantable two-way neural interface for wireless, multichannel streaming of field potentials in five patients with Parkinson’s disease for up to 15 months after implantation. Bilateral 4-channel motor cortex and basal ganglia field potentials streamed at home for over 2,600 hours were paired with behavioral data from wearable monitors for the neural decoding of states of inadequate or excessive movement. We validated patient-specific neurophysiological biomarkers during normal daily activities and used those patterns for adaptive deep brain stimulation. This technological approach may be widely applicable to brain disorders treatable by invasive neuromodulation.