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Patients with advanced Parkinson's disease often suffer from severe gait and balance problems, impacting quality of live and persisting despite optimization of standard therapies. The aim of this review was to systematically review the efficacy of STN-DBS programming techniques in alleviating gait disturbances in patients with advanced PD. Searches were conducted in PubMed, Embase, and Lilacs databases, covering studies published until May 2024. The review identified 36 articles that explored five distinct STN-DBS techniques aimed at addressing gait and postural instability in Parkinson's patients: low-frequency stimulation, ventral STN stimulation for simultaneous substantia nigra activation, interleaving, asymmetric stimulation and a short pulse width study. Among these, 21 articles were included in the meta-analysis, which revealed significant heterogeneity among studies. Notably, low-frequency STN-DBS demonstrated positive outcomes in total UPDRS-III score and FOG-Q, especially when combined with dopaminergic therapy. The most favorable results were found for low-frequency STN stimulation. The descriptive analysis suggests that unconventional stimulation approaches may be viable for gait problems in patients who do not respond to standard therapies.

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BACKGROUND: Deep Brain Stimulation (DBS) is FDA-approved for several movement disorders; such as Parkinson's disease, dystonia, and neuropsychiatric disorders. There are various reports of Body mass index (BMI) changes following different DBS targets in various disorders. AIM: A comprehensive systematic review and meta-analysis were conducted to investigate the impact of DBS on patients' Body Mass Index (BMI) and provide an in-depth overview of its underlying mechanisms. MATERIALS AND METHODS: We conducted research according to PRISMA guidelines. Our study assessed comprehensively electronic databases, including Pubmed, Scopus, Embase, web of science, and the Cochrane Library, up to May 2024. The random-effect model analysis was performed by the Comprehensive Meta-analysis software (CMA) version 3.0. As well, Cochran's Q test was used to determine the statistical heterogeneity of included studies. RESULT: This systematic review ultimately included 49 studies, 46 of which entered the meta-analysis. The total number of patients was 1478, consisting of Parkinson's disease (PD), dystonia, and the obsessive compulsive disorder (OCD) patients. The most common DBS target was subthalamic nucleus, followed by globus pallidus internus (GPi). Our meta-analysis depicted the BMI of participants significantly mount after DBS electrode implantation (SMD = -0.542, 95%CI: -0.678 to -0.406, and P-value < 0.001). However, moderate to high heterogeneity was detected among the studies (I2 = 67.566%). Additionally, the Daily energy intake (DEI) of patients significantly decreased after DBS (SMD: 0.457, 95%CI; 0.205 to 0.709, and P-value < 0.001). CONCLUSION: STN and GPi DBS can lead to weight gain through distinct central pathways in various movement and neuropsychiatric disorders, posing a potential risk for obesity, insulin resistance, and metabolic syndrome.

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BACKGROUND: Speech changes significantly impact the quality of life for Parkinson's disease (PD) patients. Deep Brain Stimulation (DBS) of the Subthalamic Nucleus (STN) is a standard treatment for advanced PD, but its effects on speech remain unclear. This study aimed to investigate the relationship between STN-DBS and speech changes in PD patients using comprehensive clinical assessments and tractography. METHODS: Forty-seven PD patients underwent STN-DBS, with preoperative and 3-month postoperative assessments. Speech analyses included acoustic measurements, auditory-perceptual evaluations, and fluency-intelligibility tests. On the other hand, structures within the volume tissue activated (VTA) were identified using MRI and DTI. The clinical and demographic data and structures associated with VTA (Corticospinal tract, Internal capsule, Dentato-rubro-thalamic tract, Medial forebrain bundle, Medial lemniscus, Substantia nigra, Red nucleus) were compared with speech analyses. RESULTS: The majority of patients (36.2-55.4% good, 29.7-53.1% same) exhibited either improved or unchanged speech quality following STN-DBS. Only a small percentage (8.5-14.9%) experienced deterioration. Older patients and those with worsened motor symptoms postoperatively were more likely to experience negative speech changes (p < 0.05). Interestingly, stimulation of the right Substantia Nigra correlated with improved speech quality (p < 0.05). No significant relationship was found between other structures affected by VTA and speech changes. CONCLUSIONS: This study suggests that STN-DBS does not predominantly negatively impact speech in PD patients, with potential benefits observed, especially in younger patients. These findings underscore the importance of individualized treatment approaches and highlight the need for further long-term studies to optimize therapeutic outcomes and better understand the effects of STN-DBS on speech.

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PURPOSE: To describe the effects of subthalamic nucleus deep brain stimulation (STN-DBS) on the speech of Spanish-speaking Parkinson's disease (PD) patients during the first year of treatment. METHODS: The speech measures (SMs): maximum phonation time, acoustic voice measures, speech rate, speech intelligibility measures, and oral diadochokinesis rates of nine Colombian idiopathic PD patients (four females and five males; age = 63 ± 7 years; years of PD = 10 ± 7 years; UPDRS-III = 57 ± 6; H&Y = 2 ± 0.3) were studied in OFF and ON medication states before and every three months during the first year after STN-DBS surgery. Praat software and healthy native listeners' ratings were used for speech analysis. Statistical analysis tried to find significant differences in the SMs during follow-up (Friedman test) and between medication states (Wilcoxon paired test). Also, a pre-surgery variation interval (PSVI) of reference for every participant and SM was calculated to make an individual analysis of post-surgery variation. RESULTS: Non-significative post-surgery or medication state-related differences in the SMs were found. Nevertheless, individually, based on PSVIs, the SMs exhibited: no variation, inconsistent or consistent variation during post-surgery follow-up in different combinations, depending on the medication state. CONCLUSION: As a group, participants did not have a shared post-surgery pattern of change in any SM. Instead, based on PSVIs, the SMs varied differently in every participant, which suggests that in Spanish-speaking PD patients, the effects of STN-DBS on speech during the first year of treatment could be highly variable.

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The ability to switch between rules associating stimuli and responses depend on a circuit including the dorsomedial prefrontal cortex (dmPFC) and the subthalamic nucleus (STN). However, the precise neural implementations of switching remain unclear. To address this issue, we recorded local field potentials from the STN and from the dmPFC of neuropsychiatric patients during behavioral switching. Drift-diffusion modeling revealed that switching is associated with a shift in the starting point of evidence accumulation. Theta activity increases in dmPFC and STN during successful switch trials, while temporally delayed and excessive levels of theta lead to premature switch errors. This seemingly opposing impact of increased theta in successful and unsuccessful switching is explained by a negative correlation between theta activity and the starting point. Together, these results shed a new light on the neural mechanisms underlying the rapid reconfiguration of stimulus-response associations, revealing a Goldilocks' effect of theta activity on switching behavior.

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Introduction: Subthalamic nucleus deep brain stimulation (STN-DBS) is a proven treatment modality for Parkinson's disease (PD), reducing dyskinesia and time spent in the "OFF" state. This study evaluates the long-term outcomes of STN-DBS in PD patients up to 10 years post-surgery in Singapore. Method: We conducted a retrospective review of Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) scores, activities of daily living (ADLs), disease milestones, dopaminergic drug prescriptions, and adverse events in patients before and after STN-DBS surgery. Results: A total of 94 PD patients who underwent bilateral STN-DBS were included. STN-DBS reduced time in the "OFF" state by 36.9% at 1 year (P=0.034) and 40.9% at 5 years (P=0.006). Time with dyskinesia did not significantly change. Levodopa equivalent daily dose was reduced by 35.1% by 5 years (P<0.001). MDS-UPDRS-II and III scores increased from 5 years post-DBS by 40.5% and 35.4%, respectively. Independence in ADLs decreased, though not significantly. The prevalence of frequent falls increased at 5 years. Surgery- and device-related adverse events were uncommon and generally mild. Conclusion: STN-DBS provides sustained relief from motor complications and reduced medication requirements in PD patients in Singapore. This study highlights STN-DBS as an effective treatment option, significantly enhancing the quality of life for those with PD.

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OBJECTIVE: Parkinson's disease (PD) as a neurodegenerative disorder characterized by a reduction in both the quantity and functionality of dopaminergic neurons. This succinctly highlights the central pathological feature of PD and its association with dopaminergic neuron degeneration, which underlies the motor and non-motor symptoms of the disease. This study aims to elucidate the nuances of apparent diffusion coefficient (ADC) changes in different cerebral regions by after the bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) surgery of PD, as well as to investigate their potential interactions with the motor and neuropsychiatric spectrum. METHODS: Patients who underwent STN-DBS surgery for PD between 2017 and 2019 were included in this study. The results of diffusion magnetic resonance imaging (MRI), Unified Parkinson Disease Rating Scale (UPDRS) III scores, Beck and Hamilton depression tests were recorded before and at the 3rd month of postoperative stimulation. The data obtained were evaluated with the Wilcoxon signed rank test. Result of the statistical tests were within the 95 % confidence interval and p values were significant below 0.05. RESULTS: Our study was conducted with a total of 13 patients, 8 men and 5 women. As a result of measurements made in a total of 32 different regions, especially in the motor and neuropsychiatric areas of the brain, an increase in ADC values was found in all areas. ADC changes of eight localizations such as left corpus callosum, right corona radiata, left corona radiata, hippocampus, right insula, left superior cerebellar peduncle, left caudate nucleus and left putamen were statistically significant. UPDRS III scores improved by 57 % (p <0.05), and Beck and Hamilton depression scores by 25 % and 33 %, respectively (p> 0.05). CONCLUSIONS: This article implicate that bilateral STN-DBS surgery potentially exerts beneficial effects on both motor and neuropsychiatric symptomatology in individuals with PD. We believe that this therapeutic mechanism is hypothesized to involve modulation of diffusion alterations within distinct cerebral tissues.

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The neural network mediating successful response inhibition mainly includes right hemisphere activation of the pre-supplementary motor area, inferior frontal gyrus (IFG), subthalamic nucleus (STN), and caudate nucleus. However, the causal role of these regions in the inhibitory network is undefined. Five patients with Parkinson's disease were assessed prior to and after therapeutic thermal ablation of the right STN in two separate functional magnetic resonance imaging (fMRI) sessions while performing a stop-signal task. Initiation times were faster but motor inhibition with the left hand (contralateral to the lesion) was significantly impaired as evident in prolonged stop-signal reaction times. Reduced inhibition after right subthalamotomy was associated (during successful inhibition) with the recruitment of basal ganglia regions outside the established inhibitory network. They included the putamen and caudate together with the anterior cingulate cortex and IFG of the left hemisphere. Subsequent network connectivity analysis (with the seed over the nonlesioned left STN) revealed a new inhibitory network after right subthalamotomies. Our results highlight the causal role of the right STN in the neural network for motor inhibition and the possible basal ganglia mechanisms for compensation upon losing a key node of the inhibition network.

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Chronic predator stress (CPS) is an important and ecologically relevant tool for inducing anhedonia in animals, but the neural circuits underlying the associated neurobiological changes remain to be identified. Using cell-type-specific manipulations, we found that corticotropin-releasing hormone (CRH) neurons in the medial subthalamic nucleus (mSTN) enhance struggle behaviors in inescapable situations and lead to anhedonia, predominately through projections to the external globus pallidus (GPe). Recordings of in vivo neuronal activity revealed that CPS distorted mSTN-CRH neuronal responsivity to negative and positive stimuli, which may underlie CPS-induced behavioral despair and anhedonia. Furthermore, we discovered presynaptic inputs from the bed nucleus of the stria terminalis (BNST) to mSTN-CRH neurons projecting to the GPe that were enhanced following CPS, and these inputs may mediate such behaviors. This study identifies a neurocircuitry that co-regulates escape response and anhedonia in response to predator stress. This new understanding of the neural basis of defensive behavior in response to predator stress will likely benefit our understanding of neuropsychiatric diseases.

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INTRODUCTION: Parkinson's disease (PD) can affect the intelligibility of speech. Although studies of vowel production are useful for measuring this impairment, they do not exist in Spanish speakers with the disease who have been treated with subthalamic nucleus deep brain stimulation (STN-DBS). STN-DBS is an effective treatment for the classic signs of PD, but with varied effects on speech. PATIENTS AND METHODS: Data from two individuals with PD treated with STN-DBS were studied: one (P1) had impairment and the other (P2) had stable speech intelligibility after STN-DBS implantation. The triangular vowel space area (tVSA) and the vowel articulation index (VAI) were measured and compared before the implantation surgery, and at three, six and nine months after surgery. These measurements were compared with measurements of speech intelligibility (percentage of words correctly identified and degree of intelligibility). RESULTS: Both participants presented variations in measurements of vowel articulation after surgery. In P1, the reduction in the tVSA, but not the post-surgical change in the VAI, was consistent with reduced speech intelligibility. However, in P2, both measurements (tVSA and VAI) reflected stable speech intelligibility after surgery. CONCLUSIONS: Reduced speech intelligibility in Spanish speakers with PD after STN-DBS implantation may be reflected in a reduced tVSA.

TITLE: Articulación de las vocales e inteligibilidad del habla en hispanohablantes con enfermedad de Parkinson tratados con estimulación cerebral profunda del núcleo subtalámico.Introducción. La enfermedad de Parkinson (EP) puede alterar la inteligibilidad del habla. Aunque los estudios de la producción de las vocales son útiles para medir esta afectación, no existen en hispanohablantes con la enfermedad que hayan sido tratados con estimulación cerebral profunda del núcleo subtalámico (STN-DBS). La STN-DBS es un tratamiento efectivo para los signos clásicos de la EP, pero con variados efectos en el habla. Pacientes y métodos. Se estudiaron los datos de dos personas con EP tratadas con STN-DBS: uno (P1) con deterioro y el otro (P2) con estabilidad de la inteligibilidad del habla después de la implantación de la STN-DBS. Se calcularon y compararon medidas de espacio vocálico acústico triangular (tVSA) e índice de articulación de las vocales (VAI) antes de la cirugía de implantación y a los tres, seis y nueve meses de la intervención. Estas medidas se contrastaron con medidas de inteligibilidad del habla (porcentaje de palabras correctamente identificadas y grado de inteligibilidad). Resultados. Ambos participantes mostraron variación de las medidas de articulación de las vocales después de la cirugía. En P1, la reducción del tVSA, pero no el cambio posquirúrgico del VAI, correspondió con disminución de la inteligibilidad del habla. Por el contrario, en P2, el comportamiento de ambas medidas (tVSA y VAI) reflejó la estabilidad de la inteligibilidad del habla después de la cirugía. Conclusiones. La reducción de la inteligibilidad del habla en hispanohablantes con EP después de la implantación de la STN-DBS puede reflejarse en la reducción del tVSA.

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While deep brain stimulation (DBS) is widely employed for managing motor symptoms in Parkinson's disease (PD), its exact circuit mechanisms remain controversial. To identify the neural targets affected by therapeutic DBS in PD, we analyzed DBS-evoked whole brain activity in female hemi-parkinsonian rats using functional magnetic resonance imaging (fMRI). We delivered subthalamic nucleus (STN) DBS at various stimulation pulse repetition rates using optogenetics, allowing unbiased examination of cell-type specific STN feedforward neural activity. Unilateral optogenetic STN DBS elicited pulse repetition rate-dependent alterations of blood-oxygenation-level-dependent (BOLD) signals in SNr (substantia nigra pars reticulata), GP (globus pallidus), and CPu (caudate putamen). Notably, this modulation effectively ameliorated pathological circling behavior in animals expressing the kinetically faster Chronos opsin, but not in animals expressing ChR2. Furthermore, mediation analysis revealed that the pulse repetition rate-dependent behavioral rescue was significantly mediated by optogenetic DBS induced activity changes in GP and CPu, but not in SNr. This suggests that the activation of GP and CPu are critically involved in the therapeutic mechanisms of STN DBS.

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BACKGROUND AND OBJECTIVES: Despite the well-established efficacy of deep brain stimulation (DBS) of the subthalamic nucleus (STN) for Parkinson's Disease (PD), there remains a subset of patients with only a moderate improvement in symptoms even with appropriate lead placement and optimal programming. In patients with persistent tremor or dyskinesias, one consideration is the addition of a second "rescue lead" to provide dual stimulation to primary and secondary targets to address the refractory component. This study aimed to assess all "rescue lead" cases from our institution and characterize the patients and their outcomes. METHODS: Records of all patients with PD treated at our institution between 2005 and 2023 were retrospectively reviewed. Clinical data of all patients treated with a second rescue lead to supplement a positive but inadequate initial DBS response were collected and reviewed. RESULTS: Of 670 patients with PD treated at our institution during the study period, 7 were managed with a rescue lead. All 7 were initially treated with STN DBS with a partial improvement in underlying symptoms, had confirmed appropriate lead placement, and underwent thorough programming. Four patients underwent rescue with a globus pallidus interna lead for persistent dyskinesias, all with subsequent improvement in their dyskinesias. Three patients had persistent tremors that were treated with a rescue ventrointermediate thalamus stimulation with subsequent improvement in tremor scores. There were no operative complications, and all patients tolerated dual stimulation. CONCLUSION: For a small subset of patients with PD with persistent dyskinesias or tremors after STN DBS despite optimized lead parameters and adequate lead placement, rescue lead placement offers an effective treatment option.

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Aberrant information processing in the basal ganglia and connected cortical areas are key to many neurological movement disorders such as Parkinson's disease. Investigating the electrophysiology of this system is difficult in humans because non-invasive methods, such as electroencephalography or magnetoencephalography, have limited sensitivity to deep brain areas. Recordings from electrodes implanted for therapeutic deep brain stimulation, in contrast, provide clear deep brain signals but are not suited for studying cortical activity. Therefore, we combine magnetoencephalography and local field potential recordings from deep brain stimulation electrodes in individuals with Parkinson's disease. Here, we make these data available, inviting a broader scientific community to explore the dynamics of neural activity in the subthalamic nucleus and its functional connectivity to cortex. The dataset encompasses resting-state recordings, plus two motor tasks: static forearm extension and self-paced repetitive fist clenching. Most patients were recorded both in the medicated and the unmedicated state. Along with the raw data, we provide metadata on channels, events and scripts for pre-processing to help interested researchers get started.

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Bradykinesia is a term describing several manifestations of movement disruption caused by Parkinson's disease (PD), including movement slowing, amplitude reduction, and gradual decrease of speed and amplitude over multiple repetitions of the same movement. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves bradykinesia in patients with PD. We examined the effect of DBS on specific components of bradykinesia when applied at two locations within the STN, using signal processing techniques to identify the time course of amplitude and frequency of repeated hand pronation-supination movements performed by participants with and without PD. Stimulation at either location increased movement amplitude, increased frequency, and decreased variability, though not to the range observed in the control group. Amplitude and frequency showed decrement within trials, which was similar in PD and control groups and did not change with DBS. Decrement across trials, by contrast, differed between PD and control groups, and was reduced by stimulation. We conclude that DBS improves specific aspects of movement that are disrupted by PD, whereas it does not affect short-term decrement that could reflect muscular fatigue.NEW & NOTEWORTHY In this study, we examined different components of bradykinesia in patients with Parkinson's disease (PD). We identified different components through signal processing techniques and their response to deep brain stimulation (DBS). We found that some components of bradykinesia respond to stimulation, whereas others do not. This knowledge advances our understanding of brain mechanisms that control movement speed and amplitude.

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BACKGROUND: Non-motor symptoms and non-motor fluctuations (NMF) in Parkinson's disease (PD) strongly affect health-related quality of life (HRQoL) and disability. The impact of deep brain stimulation (DBS) on NMF remains an area of uncertainty. The aim is to evaluate the impact of DBS on NMF, using the recently validated Non-Motor Fluctuation Assessment (NoMoFa), and to explore the correlation between NMF and motor symptoms, motor complications (MC), and HRQoL post-surgical improvement. METHODS: We prospectively evaluated consecutive patients undergoing subthalamic DBS (STN-DBS), at baseline and 6-months after surgery. Assessments included the NoMoFa questionnaire, the MDS-sponsored Unified Parkinson's Disease Rating Scale, and the 39-Item Parkinson's Disease Questionnaire. Pre- and post-surgical NoMoFa scores were compared using the Wilcoxon Signed rank-test. Linear regression analysis evaluated: a) the correlation between NoMoFa scores, motor and MC improvement, correcting for age, disease duration, and dopaminergic therapy reduction; b) the correlation between HRQoL and NMF improvement, correcting for age, disease duration, motor and MC improvement. RESULTS: Twenty patients were evaluated. Total NMF score significantly improved (44.6 %, [IQR = 18.3-100]; p = 0.022), particularly in Off condition (52.0 %, [IQR = 25.4-100]; p = 0.009); we observed strong correlation between NMF and MC improvement (Beta = 0.728; p = 0.006), mainly driven by the mitigation of unpredictable Off (Beta = 0.905; p < 0.001). Even after adjusting for potential confounders, the reduction of NMF independently correlated with increased HRQoL (Beta = 0.714; p = 0.010). CONCLUSIONS: STN-DBS demonstrated strong beneficial effect on NMF, resulting in significant improvement of HRQoL. This underlines the importance of recognizing NMF as a significant factor to be considered in the selection of patients eligible for STN-DBS.

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The subthalamic nucleus (STN) is traditionally thought to restrict movement. Lesion or prolonged STN inhibition increases movement vigor and propensity, while optogenetic excitation has opposing effects. However, STN neurons often exhibit movement-related increases in firing. To address this paradox, STN activity was recorded and manipulated in head-fixed mice at rest and during self-initiated and self-paced treadmill locomotion. We found that (1) most STN neurons (type 1) exhibit locomotion-dependent increases in activity, with half firing preferentially during the propulsive phase of the contralateral locomotor cycle; (2) a minority of STN neurons exhibit dips in activity or are uncorrelated with movement; (3) brief optogenetic inhibition of the lateral STN (where type 1 neurons are concentrated) slows and prematurely terminates locomotion; and (4) in Q175 Huntington's disease mice, abnormally brief, low-velocity locomotion is associated with type 1 hypoactivity. Together, these data argue that movement-related increases in STN activity contribute to optimal locomotor performance.

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BACKGROUND: Deep brain stimulation of the subthalamic nucleus (STN-DBS) is a successful treatment option in Parkinson's disease (PD) for different motor and non-motor symptoms, but has been linked to postoperative cognitive impairment. AIM: Since both dopaminergic and norepinephrinergic neurotransmissions play important roles in symptom development, we analysed STN-DBS effects on dopamine and norepinephrine availability in different brain regions and morphological alterations of catecholaminergic neurons in the 6-hydroxydopamine PD rat model. METHODS: We applied one week of continuous unilateral STN-DBS or sham stimulation, respectively, in groups of healthy and 6-hydroxydopamine-lesioned rats to quantify dopamine and norepinephrine contents in the striatum, olfactory bulb and dentate gyrus. In addition, we analysed dopaminergic cell counts in the substantia nigra pars compacta and area tegmentalis ventralis and norepinephrinergic neurons in the locus coeruleus after one and six weeks of STN-DBS. RESULTS: In 6-hydroxydopamine-lesioned animals, one week of STN-DBS did not alter dopamine levels, while striatal norepinephrine levels were decreased. However, neither one nor six weeks of STN-DBS altered dopaminergic neuron numbers in the midbrain or norepinephrinergic neuron counts in the locus coeruleus. Dopaminergic fibre density in the dorsal and ventral striatum also remained unchanged after six weeks of STN-DBS. In healthy animals, one week of STN-DBS resulted in increased dopamine levels in the olfactory bulb and decreased contents in the dentate gyrus, but had no effects on norepinephrine availability. CONCLUSIONS: STN-DBS modulates striatal norepinephrinergic neurotransmission in a PD rat model. Additional behavioural studies are required to investigate the functional impact of this finding.

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OBJECTIVE: Parkinson's disease (PD) patients exhibit changes in mechanisms underlying movement preparation, particularly the suppression of corticospinal excitability - termed "preparatory suppression" - which is thought to facilitate movement execution in healthy individuals. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) being an attractive treatment for advanced PD, we aimed to study the potential contribution of this nucleus to PD-related changes in such corticospinal dynamics. METHODS: On two consecutive days, we applied single-pulse transcranial magnetic stimulation to the primary motor cortex of 20 advanced PD patients treated with bilateral STN-DBS (ON vs. OFF), as well as 20 healthy control subjects. Motor-evoked potentials (MEPs) were elicited at rest or during movement preparation in an instructed-delay choice reaction time task including left- or right-hand responses. Preparatory suppression was assessed by expressing MEPs during movement preparation relative to rest. RESULTS: PD patients exhibited a deficit in preparatory suppression when it was probed on the responding hand side, particularly when this corresponded to their most-affected hand, regardless of their STN-DBS status. CONCLUSIONS: Advanced PD patients displayed a reduction in preparatory suppression which was not restored by STN-DBS. SIGNIFICANCE: The current findings confirm that PD patients lack preparatory suppression, as previously reported. Yet, the fact that this deficit was not responsive to STN-DBS calls for future studies on the neural source of this regulatory mechanism during movement preparation.

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Subpopulations of neurons in the subthalamic nucleus have distinct activity patterns that relate to the three hypotheses of the Drift Diffusion Model.

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