Correlation of active contact positions with the electrophysiological and anatomical subdivisions of the subthalamic nucleus in deep brain stimulation

Awake versus Asleep Anesthesia in Deep Brain Stimulation Surgery for Parkinson's Disease: A Systematic Review and Meta-Analysis

INTRODUCTION

Deep brain stimulation (DBS) is a well-established surgical therapy for patients with Parkinsons' Disease (PD). Traditionally, DBS surgery for PD is performed under local anesthesia, whereby the patient is awake to facilitate intraoperative neurophysiological confirmation of the intended target using microelectrode recordings. General anesthesia allows for improved patient comfort without sacrificing anatomic precision and clinical outcomes.

METHODS

We performed a systemic review and meta-analysis on patients undergoing DBS for PD. Published randomized controlled trials, prospective and retrospective studies, and case series which compared asleep and awake techniques for patients undergoing DBS for PD were included. A total of 19 studies and 1,900 patients were included in the analysis.

RESULTS

We analyzed the (i) clinical effectiveness - postoperative UPDRS III score, levodopa equivalent daily doses and DBS stimulation requirements. (ii) Surgical and anesthesia related complications, number of lead insertions and operative time (iii) patient's quality of life, mood and cognitive measures using PDQ-39, MDRS, and MMSE scores. There was no significant difference in results between the awake and asleep groups, other than for operative time, for which there was significant heterogeneity.

CONCLUSION

With the advent of newer technology, there is likely to have narrowing differences in outcomes between awake or asleep DBS. What would therefore be more important would be to consider the patient's comfort and clinical status as well as the operative team's familiarity with the procedure to ensure seamless transition and care.

Development of a 3D-printed, patient-specific stereotactic system for bihemispheric deep brain stimulation

The aim of the project was to develop a patient-specific stereotactic system that allows simultaneous and thus time-saving treatment of both cerebral hemispheres and that contains all spatial axes and can be used as a disposable product. Furthermore, the goal was to reduce the size and weight of the stereotactic system compared to conventional systems to keep the strain on the patient, who is awake during the operation, to a minimum. In addition, the currently mandatory computed tomography should be avoided in order not to expose the patient to harmful X-ray radiation as well as to eliminate errors in the fusion of CT and MRI data.3D printing best meets the requirements in terms of size and weight: on the one hand, the use of plastic has considerable potential for weight reduction. On the other hand, the free choice of the individual components offers the possibility to optimize the size and shape of the stereotactic system and to adapt it to the individual circumstances while maintaining the same precision. The all-in-one stereotactic system was produced by means of the Multi Jet Fusion process. As a result, the components are highly precise, stable in use, lightweight and sterilizable. The number of individual components and interfaces, which in their interaction are potential sources of error, was significantly reduced. In addition, on-site manufacturing leads to faster availability of the system.Within the project, a patient-specific stereotaxy system was developed, printed, and assembled, which enables the execution of deep brain stimulation via only three bone anchors located on the skull. Pre-developed MRI markers, which can be screwed directly onto the bone anchors via the sleeves, eliminate the need for a CT scan completely. The fusion of the data, which is no longer required, suggests an improvement in target accuracy.

Subthalamic deep brain stimulation for primary dystonia: defining an optimal location using the medial subthalamic nucleus border as anatomical reference

Introduction

Although the subthalamic nucleus (STN) has proven to be a safe and effective target for deep brain stimulation (DBS) in the treatment of primary dystonia, the rates of individual improvement vary considerably. On the premise of selecting appropriate patients, the location of the stimulation contacts in the dorsolateral sensorimotor area of the STN may be an important factor affecting therapeutic effects, but the optimal location remains unclear. This study aimed to define an optimal location using the medial subthalamic nucleus border as an anatomical reference and to explore the influence of the location of active contacts on outcomes and programming strategies in a series of patients with primary dystonia.

Methods

Data from 18 patients who underwent bilateral STN-DBS were retrospectively acquired and analyzed. Patients were assessed preoperatively and postoperatively (1 month, 3 months, 6 months, 1 year, 2 years, and last follow-up after neurostimulator initiation) using the Toronto Western Spasmodic Torticollis Rating Scale (for cervical dystonia) and the Burke-Fahn-Marsden Dystonia Rating Scale (for other types). Optimal parameters and active contact locations were determined during clinical follow-up. The position of the active contacts relative to the medial STN border was determined using postoperative stereotactic MRI.

Results

The clinical improvement showed a significant negative correlation with the y-axis position (anterior-posterior; A+, P-). The more posterior the electrode contacts were positioned in the dorsolateral sensorimotor area of the STN, the better the therapeutic effects. Cluster analysis of the improvement rates delineated optimal and sub-optimal groups. The optimal contact coordinates from the optimal group were 2.56 mm lateral, 0.15 mm anterior, and 1.34 mm superior relative to the medial STN border.

Conclusion

STN-DBS was effective for primary dystonia, but outcomes were dependent on the active contact location. Bilateral stimulation contacts located behind or adjacent to Bejjani's line were most likely to produce ideal therapeutic effects. These findings may help guide STN-DBS preoperative planning, stimulation programming, and prognosis for optimal therapeutic efficacy in primary dystonia.

Stimulation Sweet Spot in Subthalamic Deep Brain Stimulation - Myth or Reality? A Critical Review of Literature

INTRODUCTION

While deep brain stimulation (DBS) of the subthalamic nucleus (STN) has been extensively used for more than 20 years in Parkinson's disease (PD), the optimal area of stimulation to relieve motor symptoms remains elusive.

OBJECTIVE

We aimed at localizing the sweet spot within the subthalamic region by performing a systematic review of the literature.

METHOD

PubMed database was searched for published studies exploring optimal stimulation location for STN DBS in PD, published between 2000 and 2019. A standardized assessment procedure based on methodological features was applied to select high-quality publications. Studies conducted more than 3 months after the DBS procedure, employing lateralized scores and/or stimulation condition, and reporting the volume of tissue activated or the position of the stimulating contact within the subthalamic region were considered in the final analysis.

RESULTS

Out of 439 references, 24 were finally retained, including 21 studies based on contact location and 3 studies based on volume of tissue activated (VTA). Most studies (all VTA-based studies and 13 of the 21 contact-based studies) suggest the superior-lateral STN and the adjacent white matter as the optimal sites for stimulation. Remaining contact-based studies were either inconclusive (5/21), favoured the caudal zona incerta (1/21), or suggested a better outcome of STN stimulation than adjacent white matter stimulation (2/21).

CONCLUSION

Using a standardized methodological approach, our review supports the presence of a sweet spot located within the supero-lateral STN and extending to the adjacent white matter.

Accuracy of the robot-assisted procedure in deep brain stimulation

INTRODUCTION

The use of a robot-assisted technology becomes very competitive. The aim of this work was to define the accuracy of robotic assistance in deep brain stimulation surgery and to compare results with that in the literature.

METHODS

We retrospectively reviewed the accuracy of lead implantation in 24 consecutive patients who had robot-assisted (ROSA, Zimmer-Biomet) surgery for the treatment of movement disorders. Intended stereotactic coordinates (x, y, z) of contact 0 (the most distal contact at the tip of the electrode) of each definitive lead were compared with actual coordinates obtained by a postoperative CT scan. For each lead, the euclidian 3D distance between the actual and intended location of contact 0 was calculated.

RESULTS

The euclidian 3D distances between the intended and actual location of the contact 0 were 0.81 mm on the right side and 1.12 mm on the left side.

DISCUSSION

Robot-assisted technology for stereotactic surgery is safe and accurate. The association with a 3D flat-panel CT scan is an optimized procedure for deep intracranial electrode implantation.

Intraoperative microelectrode recording in Parkinson's disease subthalamic deep brain stimulation: Analysis of clinical utility

This retrospective study aims to explore the clinical utility of microelectrode recording (MER) during subthalamic deep brain stimulation (DBS) surgery in patients with Parkinson's disease (PD). We analyzed the data from 103 PD patients, who consecutively received bilateral subthalamic nucleus (STN) DBS at an experienced academic medical center. We collected demographic, clinical, and DBS related data, including intraoperative microelectrode recording data, electrode positioning, and clinical effects provided by intraoperative microstimulation. The 2 brain sides were independently analyzed and are described as first and second side (to be operated on); the first side is contralateral to motor symptoms onset. Patients were mostly men (64.1%). In both sides of the brain, percentage of agreement with the electrode final position was higher with clinical results than with intraoperative microelectrode recordings (98% vs 57% on the first implantation side, and 97% vs 58% on the second implantation side, respectively). Regarding electrode final implantation depth, 86% of electrodes were implanted between 0 mm and +2 mm in relation to anatomical target, and 95% of electrodes were implanted from -2 mm to +2 mm. Our study suggests that MER might not be necessary to achieve good clinical outcomes in PD patients undergoing STN DBS. These results support and inform the design of future prospective controlled research studies.

Deep Brain Stimulation Programming for Movement Disorders: Current Concepts and Evidence-Based Strategies

Deep brain stimulation (DBS) has become the treatment of choice for advanced stages of Parkinson's disease, medically intractable essential tremor, and complicated segmental and generalized dystonia. In addition to accurate electrode placement in the target area, effective programming of DBS devices is considered the most important factor for the individual outcome after DBS. Programming of the implanted pulse generator (IPG) is the only modifiable factor once DBS leads have been implanted and it becomes even more relevant in cases in which the electrodes are located at the border of the intended target structure and when side effects become challenging. At present, adjusting stimulation parameters depends to a large extent on personal experience. Based on a comprehensive literature search, we here summarize previous studies that examined the significance of distinct stimulation strategies for ameliorating disease signs and symptoms. We assess the effect of adjusting the stimulus amplitude (A), frequency (f), and pulse width (pw) on clinical symptoms and examine more recent techniques for modulating neuronal elements by electrical stimulation, such as interleaving (Medtronic®) or directional current steering (Boston Scientific®, Abbott®). We thus provide an evidence-based strategy for achieving the best clinical effect with different disorders and avoiding adverse effects in DBS of the subthalamic nucleus (STN), the ventro-intermedius nucleus (VIM), and the globus pallidus internus (GPi).

Deep brain stimulation for Parkinson's disease: defining the optimal location within the subthalamic nucleus

BACKGROUND

Individual motor improvement after deep brain stimulation (DBS) of the subthalamic nucleus (STN) for Parkinson's disease (PD) varies considerably. Stereotactic targeting of the dorsolateral sensorimotor part of the STN is considered paramount for maximising effectiveness, but studies employing the midcommissural point (MCP) as anatomical reference failed to show correlation between DBS location and motor improvement. The medial border of the STN as reference may provide better insight in the relationship between DBS location and clinical outcome.

METHODS

Motor improvement after 12 months of 65 STN DBS electrodes was categorised into non-responding, responding and optimally responding body-sides. Stereotactic coordinates of optimal electrode contacts relative to both medial STN border and MCP served to define theoretic DBS 'hotspots'.

RESULTS

Using the medial STN border as reference, significant negative correlation (Pearson's correlation -0.52, P<0.01) was found between the Euclidean distance from the centre of stimulation to this DBS hotspot and motor improvement. This hotspot was located at 2.8 mm lateral, 1.7 mm anterior and 2.5 mm superior relative to the medial STN border. Using MCP as reference, no correlation was found.

CONCLUSION

The medial STN border proved superior compared with MCP as anatomical reference for correlation of DBS location and motor improvement, and enabled defining an optimal DBS location within the nucleus. We therefore propose the medial STN border as a better individual reference point than the currently used MCP on preoperative stereotactic imaging, in order to obtain optimal and thus less variable motor improvement for individual patients with PD following STN DBS.

Subthalamic deep brain stimulation sweet spots and hyperdirect cortical connectivity in Parkinson's disease

OBJECTIVES

Firstly, to identify subthalamic region stimulation clusters that predict maximum improvement in rigidity, bradykinesia and tremor, or emergence of side-effects; and secondly, to map-out the cortical fingerprint, mediated by the hyperdirect pathways which predict maximum efficacy.

METHODS

High angular resolution diffusion imaging in twenty patients with advanced Parkinson's disease was acquired prior to bilateral subthalamic nucleus deep brain stimulation. All contacts were screened one-year from surgery for efficacy and side-effects at different amplitudes. Voxel-based statistical analysis of volumes of tissue activated models was used to identify significant treatment clusters. Probabilistic tractography was employed to identify cortical connectivity patterns associated with treatment efficacy.

RESULTS

All patients responded well to treatment (46% mean improvement off medication UPDRS-III [p < 0.0001]) without significant adverse events. Cluster corresponding to maximum improvement in tremor was in the posterior, superior and lateral portion of the nucleus. Clusters corresponding to improvement in bradykinesia and rigidity were nearer the superior border in a further medial and posterior location. The rigidity cluster extended beyond the superior border to the area of the zona incerta and Forel-H₂ field. When the clusters where averaged, the coordinates of the area with maximum overall efficacy was X = -10(-9.5), Y = -13(-1) and Z = -7(-3) in MNI(AC-PC) space. Cortical connectivity to primary motor area was predictive of higher improvement in tremor; whilst that to supplementary motor area was predictive of improvement in bradykinesia and rigidity; and connectivity to prefrontal cortex was predictive of improvement in rigidity.

INTERPRETATION

These findings support the presence of overlapping stimulation sites within the subthalamic nucleus and its superior border, with different cortical connectivity patterns, associated with maximum improvement in tremor, rigidity and bradykinesia.

Patient-Specific Electric Field Simulations and Acceleration Measurements for Objective Analysis of Intraoperative Stimulation Tests in the Thalamus

Despite an increasing use of deep brain stimulation (DBS) the fundamental mechanisms of action remain largely unknown. Simulation of electric entities has previously been proposed for chronic DBS combined with subjective symptom evaluations, but not for intraoperative stimulation tests. The present paper introduces a method for an objective exploitation of intraoperative stimulation test data to identify the optimal implant position of the chronic DBS lead by relating the electric field (EF) simulations to the patient-specific anatomy and the clinical effects quantified by accelerometry. To illustrate the feasibility of this approach, it was applied to five patients with essential tremor bilaterally implanted in the ventral intermediate nucleus (VIM). The VIM and its neighborhood structures were preoperatively outlined in 3D on white matter attenuated inversion recovery MR images. Quantitative intraoperative clinical assessments were performed using accelerometry. EF simulations (n = 272) for intraoperative stimulation test data performed along two trajectories per side were set-up using the finite element method for 143 stimulation test positions. The resulting EF isosurface of 0.2 V/mm was superimposed to the outlined anatomical structures. The percentage of volume of each structure’s overlap was calculated and related to the corresponding clinical improvement. The proposed concept has been successfully applied to the five patients. For higher clinical improvements, not only the VIM but as well other neighboring structures were covered by the EF isosurfaces. The percentage of the volumes of the VIM, of the nucleus intermediate lateral of the thalamus and the prelemniscal radiations within the prerubral field of Forel increased for clinical improvements higher than 50% compared to improvements lower than 50%. The presented new concept allows a detailed and objective analysis of a high amount of intraoperative data to identify the optimal stimulation target. First results indicate agreement with published data hypothesizing that the stimulation of other structures than the VIM might be responsible for good clinical effects in essential tremor. (Clinical trial reference number: Ref: 2011-A00774-37/AU905)

Targeting of the Subthalamic Nucleus for Deep Brain Stimulation: A Survey Among Parkinson Disease Specialists

BACKGROUND

Deep brain stimulation within or adjacent to the subthalamic nucleus (STN) represents the most common stereotactic procedure performed for Parkinson disease. Better STN imaging is often regarded as a requirement for improving stereotactic targeting. However, it is unclear whether there is consensus about the optimal target.

METHODS

To obtain an expert opinion on the site regarded optimal for "STN stimulation," movement disorder specialists were asked to indicate their preferred position for an active contact on hard copies of the Schaltenbrand and Wahren atlas depicting the STN in all 3 planes. This represented an idealized setting, and it mimicked optimal imaging for direct target definition in a perfectly delineated STN.

RESULTS

The suggested targets were heterogeneous, although some clustering was observed in the dorsolateral STN and subthalamic area. In particular, in the anteroposterior direction, the intended targets differed to a great extent. Most of the indicated targets are thought to also result in concomitant stimulation of structures adjacent to the STN, including the zona incerta, fields of Forel, and internal capsule.

CONCLUSIONS

This survey illustrates that most sites regarded as optimal for STN stimulation are close to each other, but there appears to be no uniform perception of the optimal anatomic target, possibly influencing surgical results. The anatomic sweet zone for STN stimulation needs further specification, as this information is likely to make magnetic resonance imaging-based target definition less variable when applied to individual patients.

Can We Rely on Susceptibility-Weighted Imaging for Subthalamic Nucleus Identification in Deep Brain Stimulation Surgery?

BACKGROUND

Susceptibility-weighted imaging (SWI) offers significantly improved visibility of the subthalamic nucleus (STN) compared with traditional T2-weighted imaging. However, it is unknown whether the representation of the nucleus on SWI corresponds to the neurophysiological location of the STN.

OBJECTIVE

To determine the correlation between the intraoperative electrophysiological activity of the STN and the representation of the nucleus on different magnetic resonance imaging (MRI) sequences used for deep brain stimulation target planning.

METHODS

At stereotactic target depth, microelectrode recordings (MERs) of typical STN neuronal activity were mapped on 3 different preoperative MRI sequences: 1.5-T SWI, 1.5-T T2-weighted, and 3-T T2-weighted MRI. For each MRI sequence, it was determined whether the MER signal was situated inside or outside the contour of the STN.

RESULTS

A total of 196 MER tracks in 34 patients were evaluated. In 165 tracks (84%), typical electrophysiological STN activity was measured. MER activity was situated more consistently inside hypointense STN contour representation on 1.5- and 3-T T2-weighted images compared with SWI (99% and 100% vs 79%, respectively). The 21% incongruence of electrophysiological STN activity outside the STN contour on SWI was seen almost exclusively in the anterior and lateral microelectrode channels.

CONCLUSION

STN representation on SWI does not correspond to electrophysiological STN borders. SWI does not correctly display the lateral part of the STN. When aiming to target the superolateral sensorimotor part of the STN during deep brain stimulation surgery, SWI does not offer an advantage but a disadvantage compared with conventional T2. Future research is needed to determine whether these findings may also apply for high-field SWI.

Stimulation sites in the subthalamic nucleus and clinical improvement in Parkinson's disease: a new approach for active contact localization

OBJECTIVE

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is widely used in patients with Parkinson's disease (PD). However, which target area of this region results in the highest antiparkinsonian efficacy is still a matter of debate. The aim of this study was to develop a more accurate methodology to locate the electrodes and the contacts used for chronic stimulation (active contacts) in the subthalamic region, and to determine the position at which stimulation conveys the greatest clinical benefit.

METHODS

The study group comprised 40 patients with PD in whom bilateral DBS electrodes had been implanted in the STN. Based on the Morel atlas, the authors created an adaptable 3D atlas that takes into account individual anatomical variability and divides the STN into functional territories. The locations of the electrodes and active contacts were obtained from an accurate volumetric assessment of the artifact using preoperative and postoperative MR images. Active contacts were positioned in the 3D atlas using stereotactic coordinates and a new volumetric method based on an ellipsoid representation created from all voxels that belong to a set of contacts. The antiparkinsonian benefit of the stimulation was evaluated by the reduction in the Unified Parkinson's Disease Rating Scale Part III (UPDRS-III) score and in the levodopa equivalent daily dose (LEDD) at 6 months. A homogeneous group classification for contact position and the respective clinical improvement was applied using a hierarchical clustering method.

RESULTS

Subthalamic stimulation induced a significant reduction of 58.0% ± 16.5% in the UPDRS-III score (p < 0.001) and 64.9% ± 21.0% in the LEDD (p < 0.001). The greatest reductions in the total and contralateral UPDRS-III scores (64% and 76%, respectively) and in the LEDD (73%) were obtained when the active contacts were placed approximately 12 mm lateral to the midline, with no influence of the position being observed in the anteroposterior and dorsoventral axes. In contrast, contacts located about 10 mm from the midline only reduced the global and contralateral UPDRS-III scores by 47% and 41%, respectively, and the LEDD by 33%. Using the ellipsoid method of location, active contacts with the highest benefit were positioned in the rostral and most lateral portion of the STN and at the interface between this subthalamic region, the zona incerta, and the thalamic fasciculus. Contacts placed in the most medial regions of the motor STN area provided the lowest clinical efficacy.

CONCLUSIONS

The authors report an accurate new methodology to assess the position of electrodes and contacts used for chronic subthalamic stimulation. Using this approach, the highest antiparkinsonian benefit is achieved when active contacts are located within the rostral and the most lateral parts of the motor region of the STN and at the interface of this region and adjacent areas (zona incerta and thalamic fasciculus).

Subthalamic nucleus volumes are highly consistent but decrease age-dependently-a combined magnetic resonance imaging and stereology approach in humans

The subthalamic nucleus (STN) is a main target structure of deep brain stimulation (DBS) in idiopathic Parkinson's disease. Nevertheless, there is an ongoing discussion regarding human STN volumes and neuron count, which could potentially have an impact on STN-DBS. Moreover, a suspected functional subdivision forms the basis of the tripartite hypothesis, which has not yet been morphologically substantiated. In this study, it was aimed to investigate the human STN by means of combined magnetic resonance imaging (MRI) and stereology. STN volumes were obtained from 14 individuals (ranging from 65 to 96 years, 25 hemispheres) in 3 T MRI and in luxol-stained histology slices. Neuron number and cell densities were investigated stereologically over the entire STN and in pre-defined subregions in anti-human neuronal protein HuC/D-stained slices. STN volumes measured with MRI were smaller than in stereology but appeared to be highly consistent, measuring on average 99 ± 6 mm³ (MRI) and 132 ± 20 mm³ (stereology). The neuron count was 431,088 ± 72,172. Both STN volumes and cell count decreased age-dependently. Neuron density was different for the dorsal, medial and ventral subregion with significantly higher values ventrally than dorsally. Small variations in STN volumes in both MRI and stereology contradict previous findings of large variations in STN size. Age-dependent decreases in STN volumes and neuron numbers might influence the efficacy of STN-DBS in a geriatric population. Though the study is limited in sample size, site-dependent differences for the STN subregions form a morphological basis for the tripartite theory. Hum Brain Mapp 38:909-922, 2017. © 2016 Wiley Periodicals, Inc.

Spatial topographies of unilateral subthalamic nucleus deep brain stimulation efficacy for ipsilateral, contralateral, midline, and total Parkinson disease motor symptoms

BACKGROUND

Subthalamic nucleus (STN) deep brain stimulation is a successful intervention for medically refractory Parkinson disease, although its efficacy depends on optimal electrode placement. Even though the predominant effect is observed contralaterally, modest improvements in ipsilateral and midline symptoms are also observed.

OBJECTIVE

To elucidate the role of contact location of unilateral deep brain stimulation on contralateral, ipsilateral, and axial subscores of Parkinson disease motor symptoms.

METHODS

Eighty-six patients receiving first deep brain stimulation STN electrode placements were identified, yielding 73 patients with 3-month follow-up. Total preoperative and postoperative Unified Parkinson Disease Rating Scale Part III scores were obtained and divided into contralateral, ipsilateral, and midline subscores. Contact location was determined on immediate postoperative magnetic resonance imaging. A 3-dimensional ordinary "kriging" algorithm generated spatial interpolations for total, ipsilateral, contralateral, and midline symptom categories. Interpolative reconstructions were performed in the axial planes (z = -0.5, -1.0, -1.5, -3.5, -4.5, -6.0) and a sagittal plane (x = 12.0). Interpolation error and significance were quantified by use of a cross-validation technique and quantile-quantile analysis.

RESULTS

There was an overall reduction in Unified Parkinson Disease Rating Scale Part III symptoms: total = 37.0 ± 24.11% (P < .05), ipsilateral = 15.9 ± 51.8%, contralateral = 56.2 ± 26.8% (P < .05), and midline = 26.5 ± 34.7%. Kriging interpolation was performed and cross-validated with quantile-quantile analysis with high correlation (R2 > 0.92) and demonstrated regions of efficacy for each symptom category. Contralateral symptoms demonstrated broad regions of efficacy across the peri-STN area. The ipsilateral and midline regions of efficacy were constrained and located along the dorsal STN and caudal zona incerta.

CONCLUSION

We provide evidence for a unique functional topographic window in which contralateral, ipsilateral, and midline structures may achieve the best efficacy. Although there are overlapping regions, laterality demonstrates distinct topographies. Surgical optimization should target the intersection of optimal regions for these symptom categories.

Subthalamic nucleus deep brain stimulation induces motor network BOLD activation: use of a high precision MRI guided stereotactic system for nonhuman primates

BACKGROUND

Functional magnetic resonance imaging (fMRI) is a powerful method for identifying in vivo network activation evoked by deep brain stimulation (DBS).

OBJECTIVE

Identify the global neural circuitry effect of subthalamic nucleus (STN) DBS in nonhuman primates (NHP).

METHOD

An in-house developed MR image-guided stereotactic targeting system delivered a mini-DBS stimulating electrode, and blood oxygenation level-dependent (BOLD) activation during STN DBS in healthy NHP was measured by combining fMRI with a normalized functional activation map and general linear modeling.

RESULTS

STN DBS significantly increased BOLD activation in the sensorimotor cortex, supplementary motor area, caudate nucleus, pedunculopontine nucleus, cingulate, insular cortex, and cerebellum (FDR < 0.001).

CONCLUSION

Our results demonstrate that STN DBS evokes neural network grouping within the motor network and the basal ganglia. Taken together, these data highlight the importance and specificity of neural circuitry activation patterns and functional connectivity.

Asymmetric right/left encoding of emotions in the human subthalamic nucleus

Emotional processing is lateralized to the non-dominant brain hemisphere. However, there is no clear spatial model for lateralization of emotional domains in the basal ganglia. The subthalamic nucleus (STN), an input structure in the basal ganglia network, plays a major role in the pathophysiology of Parkinson's disease (PD). This role is probably not limited only to the motor deficits of PD, but may also span the emotional and cognitive deficits commonly observed in PD patients. Beta oscillations (12–30 Hz), the electrophysiological signature of PD, are restricted to the dorsolateral part of the STN that corresponds to the anatomically defined sensorimotor STN. The more medial, more anterior and more ventral parts of the STN are thought to correspond to the anatomically defined limbic and associative territories of the STN. Surprisingly, little is known about the electrophysiological properties of the non-motor domains of the STN, nor about electrophysiological differences between right and left STNs. In this study, microelectrodes were utilized to record the STN spontaneous spiking activity and responses to vocal non-verbal emotional stimuli during deep brain stimulation (DBS) surgeries in human PD patients. The oscillation properties of the STN neurons were used to map the dorsal oscillatory and the ventral non-oscillatory regions of the STN. Emotive auditory stimulation evoked activity in the ventral non-oscillatory region of the right STN. These responses were not observed in the left ventral STN or in the dorsal regions of either the right or left STN. Therefore, our results suggest that the ventral non-oscillatory regions are asymmetrically associated with non-motor functions, with the right ventral STN associated with emotional processing. These results suggest that DBS of the right ventral STN may be associated with beneficial or adverse emotional effects observed in PD patients and may relieve mental symptoms in other neurological and psychiatric diseases.