The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Lars Timmermann - One of the best experts on this subject based on the ideXlab platform.
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decoding voluntary movements and Postural Tremor based on thalamic lfps as a basis for closed loop stimulation for essential Tremor
Brain Stimulation, 2019Co-Authors: Huiling Tan, Jean Debarros, Alek Pogosyan, Tipu Z Aziz, Yongzhi Huang, Shouyan Wang, Lars TimmermannAbstract:Abstract Background High frequency Deep brain stimulation (DBS) targeting motor thalamus is an effective therapy for essential Tremor (ET). However, conventional continuous stimulation may deliver unnecessary current to the brain since Tremor mainly affects voluntary movements and sustained postures in ET. Objective We aim to decode both voluntary movements and the presence of Postural Tremor from the Local field potentials (LFPs) recorded from the electrode implanted in motor thalamus for stimulation, in order to close the loop for DBS so that stimulation could be delivered on demand, without the need for peripheral sensors or additional invasive electrodes. Methods LFPs from the motor thalamus, surface electromyographic (EMG) signals and/or behavioural measurements were simultaneously recorded in seven ET patients during temporary lead externalisation 3–5 days after the first surgery for DBS when they performed different voluntary upper limb movements. Nine different patients were recorded during the surgery, when they were asked to lift their arms to trigger Postural Tremor. A machine learning based binary classifier was used to detect voluntary movements and Postural Tremor based on features extracted from thalamic LFPs. Results Cross-validation demonstrated that both voluntary movements and Postural Tremor can be decoded with an average sensitivity of 0.8 and false detection rate of 0.2. Oscillatory activities in the beta frequency bands (13–23 Hz) and the theta frequency bands (4–7 Hz) contributed most to the decoding of movements and Postural Tremor, respectively, though incorporating features in different frequency bands using a machine learning approach increased the accuracy of decoding.
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decoding voluntary movements and Postural Tremor based on thalamic lfps for closed loop stimulation for essential Tremor
bioRxiv, 2018Co-Authors: Huiling Tan, Lars Timmermann, Jean Debarros, Alek Pogosyan, Tipu Z Aziz, Yongzhi Huang, Shouyan Wang, Veerle Visservandewalle, David J Pedrosa, Alexander L GreenAbstract:High frequency deep brain stimulation (DBS) targeting motor thalamus is an effective therapy for essential Tremor (ET). However, conventional continuous stimulation may deliver unnecessary current to the brain since Tremor mainly affects voluntary movements and sustained postures in ET. We recorded LFPs from the motor thalamus, surface electromyographic (EMG) signals and/or behavioural measurements in seven ET patients during temporary lead externalization after the first surgery for DBS when they performed different voluntary upper limb movements and in nine more patients during the surgery, when they were asked to lift their arms to trigger Postural Tremor. We show that both voluntary movements and Postural Tremor can be decoded based on features extracted from thalamic LFPs using a machine learning based binary classifier. This information can be used to close the loop for DBS so that stimulation could be delivered on demand, without the need for peripheral sensors or additional invasive electrodes.
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coherence analysis of local field potentials in the subthalamic nucleus differences in parkinsonian rest and Postural Tremor
European Journal of Neuroscience, 2010Co-Authors: Christiane Reck, Alfons Schnitzler, Lars Wojtecki, Matthias Himmel, Esther Florin, Mohammad Maarouf, Volker Sturm, Gereon R Fink, Lars TimmermannAbstract:Implantation of electrodes in the subthalamic nucleus (STN) for deep brain stimulation is a well-established method to ameliorate motor symptoms in patients suffering from Parkinson's disease (PD). This study investigated the pathophysiology of rest and Postural Tremor in PD. In 14 patients with PD, we recorded intraoperatively local field potentials (LFPs) in the STN (at different recording depths) and electromyographic signals (EMGs) of the contralateral forearm. Using coherence analysis we analysed Tremor epochs both at rest and hold conditions in patients of the akinetic-rigid or of the Tremor-dominant PD subtype. Data analysis revealed significant LFP-EMG coherence during periods of rest and Postural Tremor. However, strong differences between both Tremor types were observed: local maxima (cluster) of rest and Postural Tremor did not match. Additionally, during rest Tremor coherence occurred significantly more frequently at single Tremor frequency than at double Tremor frequency in Tremor-dominant as well as in akinetic-rigid patients. In contrast, during Postural Tremor in patients with akinetic-rigid PD coherence was predominantly at double Tremor frequency. The data suggest a specific topography of 'Tremor clusters' for rest and Postural Tremor. Furthermore, we presume that the same Tremor mechanisms exist in patients with Tremor-dominant and akinetic-rigid PD, but to different degrees.
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Postural Tremor in wilson s disease a magnetoencephalographic study
Movement Disorders, 2004Co-Authors: Martin Sudmeyer, Bettina Pollok, Harald Hefter, Joachim Gross, Lars Wojtecki, Markus Butz, Lars Timmermann, Alfons SchnitzlerAbstract:The following study included 5 Wilson's disease (WD) patients showing a right-sided Postural forearm Tremor (4-6 Hz) and addressed the question of whether the primary motor cortex (M1) is involved in Tremor generation. Using a 122-channel whole-head neuromagnetometer and surface electromyogram (EMG), we investigated cerebromuscular coupling. Postural Tremor was observed in a sustained 45-degree posture of the right-sided forearm. Data were analyzed using dynamic imaging of coherent sources (DICS), revealing cerebromuscular coupling between EMG and cerebral activity. Coherent sources were superimposed on individual high-resolution T1-weighted magnetic resonance images (MRI). Phase lags between EMG and cerebral areas showing strongest coherence were determined by means of a Hilbert transform of both signals. In all patients, Postural Tremor was associated with strong coherence between Tremor EMG and activity in contralateral primary sensorimotor cortex (S1/M1) at Tremor or double Tremor frequency. Phase lag values between S1/M1 activity and EMG revealed efferent and afferent components in the corticomuscular coupling. Taken together, our results indicate that Postural Tremor in WD is mediated through a pathological oscillatory drive from the primary motor cortex.
Mario Manto - One of the best experts on this subject based on the ideXlab platform.
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a Postural Tremor highly responsive to transcranial cerebello cerebral dcs in arca3
Frontiers in Neurology, 2017Co-Authors: Florian Bodranghien, Nordeyn Oulad Ben Taib, Lionel Van Maldergem, Mario MantoAbstract:Background and Objectives: Cerebellar ataxias are disabling disorders which impact on the quality of life of patients. In many cases, an effective treatment is missing. Despite the increasing knowledge on the pathogenesis of cerebellar disorders including genetic aspects, there is currently a gap in the therapeutical management of cerebellar deficits. Cerebellar ataxia associated with ANO10 mutation (ARCA3) presents with a disabling cerebellar syndrome. To report a patient with a marked Postural Tremor responding to transcranial cerebello-cerebral direct current stimulation (tCCDCS). Methods: We applied tCCDCS using anodal stimulation over the cerebellum with a return electrode on the contralateral motor cortex. We performed a clinical rating, accelerometry studies and recordings of voluntary movements at baseline, after sham and after active tCCDCS. Results: A dramatic response of Postural Tremor was observed after tCCDCS, with a major drop of the power spectral density (PSD) to 26.12 % of basal values. Discussion: The Postural Tremor of cerebellar ataxia associated with ANO10 mutation was highly responsive to tCCDCS in our patient. This case illustrates that tCCDCS is a novel therapeutic option in the treatment of cerebellar deficits and might represent a promising tool to reduce Tremor in ARCA3.
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sensory electrical stimulation for suppression of Postural Tremor in patients with essential Tremor
Bio-medical Materials and Engineering, 2015Co-Authors: Jaehoon Heo, Do Young Kwon, Gwang Moon Eom, Jiwon Kim, Yuri Y Kwon, Sangki Lee, Channyeong C N Lee, Kunwoo K W Park, Mario MantoAbstract:Essential Tremor is an involuntary trembling of body limbs in people without Tremor-related disease. In previous study, suppression of Tremor by sensory electrical stimulation was confirmed on the index finger. This study investigates the effect of sensory stimulation on multiple segments and joints of the upper limb. It denotes the observation regarding the effect's continuity after halting the stimulation. 18 patients with essential Tremor (8 men and 10 women) participated in this study. The task, "arms stretched forward", was performed and sensory electrical stimulation was applied on four muscles of the upper limb (Flexor Carpi Radialis, Extensor Carpi Radialis, Biceps Brachii, and Triceps Brachii) for 15 seconds. Three 3-D gyro sensors were used to measure the angular velocities of segments (finger, hand, and forearm) and joints (metacarpophalangeal and wrist joints) for three phases of pre-stimulation (Pre), during-stimulation (On), and 5 minute post-stimulation (P5). Three characteristic variables of root-mean-squared angular velocity, peak power, and peak power frequency were derived from the vector sum of the sensor signals. At On phase, RMS velocity was reduced from Pre in all segments and joints while peak power was reduced from Pre in all segments and joints except for forearm segment. Sensory stimulation showed no effect on peak power frequency. All variables at P5 were similar to those at On at all segments and joints. The decrease of peak power of the index finger was noted by 90% during stimulation from that of On phase, which was maintained even after 5 min. The results indicate that sensory stimulation may be an effective clinical method to treat the essential Tremor.
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effects of inertia and wrist oscillations on contralateral neurological Postural Tremor using the wristalyzer a new myohaptic device
IEEE Transactions on Biomedical Circuits and Systems, 2008Co-Authors: Giuliana Grimaldi, Piet Lammertse, N Van Den Braber, J Meuleman, Mario MantoAbstract:Upper limb Postural Tremor consists of mechanical-reflex and central-neurogenic oscillations, superimposed upon a background of irregular fluctuations in muscle force. Muscle spindles play key-roles in the information flow to supra-spinal and spinal generators. Oscillations were delivered using a new generation portable myohaptic device, called ldquowristalyzer,rdquo taking into account the ergonomy of upper limbs and allowing a fine adjustment to each configuration of upper limb segments. The nominal torque of the first generation device is 4 Nm, with a maximal rotation velocity of 300 degrees/s and a range of motion of plusmn45 degrees. Reliability was assessed in basal condition and during loading conditions. We assessed the effects of the addition of inertia on Postural Tremor of the finger in a group of 26 neurological patients and the effects of wrist oscillations upon contralateral Postural Tremor in 6 control subjects and in 7 neurological patients exhibiting a Postural Tremor. Patients showed two different behaviors in response to inertia and exhibited an increased variability of Postural Tremor during fast oscillations (13.3 Hz). One patient with overactivity of the olivocerebellar pathways exhibited a drop in the peak frequency of more than 20%. The relative power of the 8-12 Hz subband was significantly higher in controls both in basal condition and during oscillations (p = 0.028 and p = 0.015, respectively). The second generation wristalyzer allows to investigate the effects of mechanical oscillations up to frequency of 50 Hz. This mechatronic device can assess the responsiveness of Tremor generators to stimulation of muscle spindles and biomechanical loading. Potential applications are the monitoring of dysmetria under various inertial or damping conditions, the assessment of rigidity in Parkinson's disease and the characterization of voluntary muscle force.
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Effects of wrist oscillations on contralateral neurological Postural Tremor using a new myohaptic device ('wristalyzer')
2007 4th IEEE EMBS International Summer School and Symposium on Medical Devices and Biosensors, 2007Co-Authors: Giuliana Grimaldi, Lammertse Piet, Mario MantoAbstract:Upper limb Postural Tremor consists of distinct oscillations, mainly mechanical-reflex and central-neurogenic. These oscillations are superimposed upon a background of irregular fluctuations in muscle force. Muscle spindles play key-roles in the information flow to supra-spinal and spinal generators. Oscillations were delivered using a new generation portable myohaptic device, called 'wristalyzer', which takes into account the ergonomy of upper limbs allowing a fine adjustment to each configuration of upper limb segments. The nominal torque of the device is 4 Nm, with a maximal rotation velocity of 300 degrees/s and a range of motion of +45 to -45 degrees. Reliability was assessed in basal condition and during loading conditions. We assessed the effects of wrist oscillations upon contralateral Postural Tremor in 6 control subjects and in 7 neurological patients exhibiting a Postural Tremor in upper limbs. Patients exhibited an increased variability of Postural Tremor during fast oscillations (13.3 Hz). One patient with overactivity of the olivocerebellar pathways exhibited a drop in the peak frequency of more than 20 %. The relative power of the 8-12 Hz subband was significantly higher in controls both in basal condition and during oscillations (p = 0.028 and p = 0.015, respectively). This new device could be used to increase our knowledge of the responsiveness of Tremor generators to stimulation of muscle spindles. It has also several potential applications for telemedicine in neurological rehabilitation.
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reversible cerebellar gait ataxia with Postural Tremor during episodes of high pyrexia
Clinical Neurology and Neurosurgery, 1996Co-Authors: Mario Manto, Helge TopkaAbstract:We describe five patients presenting with high fever and isolated cerebellar gait ataxia. In all these patients, neurological examination revealed dysmetria, intention Tremor and Postural Tremor during sustained posture, all restricted to the legs. Brain MRI was normal. In four of these patients, the recording of leg Tremor during sustained postures showed a 3-Hz frequency. Cerebellar gait ataxia resolved within 3-10 days. We suggest that the ataxic gait was due to a reversible dysfunction of the spinocerebellar part of the anterior lobe.
Elan D. Louis - One of the best experts on this subject based on the ideXlab platform.
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Postural and intention Tremors a detailed clinical study of essential Tremor vs parkinson s disease
Frontiers in Neurology, 2013Co-Authors: Roy N Alcalay, Eliezer J Sternberg, Oren Levy, Elan D. LouisAbstract:ABSTRACT Background: An estimated 30-50% of essential Tremor diagnoses are incorrect, and the true diagnosis in those patients is often Parkinson’s disease or other Tremor disorders. There are general statements about the Tremor in these essential Tremor and Parkinson’s disease, but published data on the more subtle characteristics of Tremor are surprisingly limited. Postural Tremor may occur in both disorders, adding to the difficulty. There are several anecdotal impressions regarding specific features of Postural Tremor in essential Tremor vs. Parkinson’s disease, including joint distribution (e.g., phalanges, metacarpal-phalangeal joints, wrist), Tremor directionality (e.g., flexion-extension vs. pronation-supination), and presence of intention Tremor. However, there is little data to support these impressions. Methods: In this cross-sectional study, 100 patients (essential Tremor, 50 Parkinson’s disease) underwent detailed videotaped neurological examinations. Arm Tremor was rated by a movement disorder neurologist who assessed severity and directionality across multiple joints. Results: During sustained arm extension, essential Tremor patients exhibited more wrist than metacarpal-phalangeal and phalangeal joint Tremor than did Parkinson’s disease patients (p<0.001), and more wrist flexion-extension Tremor than wrist pronation-supination Tremor (p<0.001). During the finger-nose-finger maneuver, intention Tremor was present in approximately one in four (28%) essential Tremor patients vs. virtually none (4%) of the Parkinson’s patients (p<0.001). Conclusions: We evaluated the location, severity, and directionality of Postural Tremor in essential Tremor and Parkinson’s disease, and the presence of intention Tremor, observing several clinical differences. We hope that detailed phenomenological data on Tremor in essential Tremor and Parkinson’s disease will help practicing physicians delineate the two diseases.
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the primary type of Tremor in essential Tremor is kinetic rather than Postural cross sectional observation of Tremor phenomenology in 369 cases
European Journal of Neurology, 2013Co-Authors: Elan D. LouisAbstract:Background Essential Tremor (ET) is amongst the most commonly misdiagnosed neurological diseases. The current aim was to provide observational data on a basic characteristic of ET, namely, the relative severity of Postural to kinetic Tremor. Methods A total of 369 ET cases were enrolled in a cross-sectional study. Postural Tremor scores (0–3) and kinetic Tremor scores (0–3) were assigned during a standardized neurological examination. Results In the vast bulk of cases (~95%), kinetic Tremor was more severe than Postural Tremor. In nearly one-in-three cases (32.8%), the kinetic Tremor score was ≥1 points higher than the Postural Tremor score. Conversely, in only a few cases (~5%) was Postural Tremor even marginally (<1 point) more severe than kinetic Tremor, and in no case was the Postural Tremor score ≥1 point higher than the kinetic Tremor score. At each Postural Tremor score, nearly all cases had that amount of kinetic Tremor or more. Conclusion The primary type of Tremor in ET is kinetic rather than Postural. Recognition of the simple, empirical features of Tremor phenomenology has potential diagnostic value for practicing clinicians.
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Brief Reports Harmaline-Induced Tremor in Mice: Videotape Documentation and Open Questions about the Model
2013Co-Authors: Melody M. Cheng, Guomei Tang, Sheng-han Kuo, Elan D. LouisAbstract:Background: Harmaline-induced Tremor in rodents has been extensively used as an animal model for essential Tremor (ET). However, there is no visual documentation in the published literature. Methods: We injected mice subcutaneously with either 20 mg/kg of harmaline hydrochloride or saline and then videotaped the responses. Results: Action and Postural Tremor in the mouse began 5 minutes after subcutaneous harmaline injection and peaked at approximately 30 minutes. The Tremor involved the head, trunk, tail, and four limbs and lasted for approximately 2 hours. The forelimb Tremor was Postural or action Tremor, similar to that observed in ET. Discussion: This video segment provides the first visual documentation of the phenomenology of harmaline-induced Tremor in a mouse. We also raise several unanswered questions regarding the use of harmaline-induced Tremor to model ET.
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is essential Tremor predominantly a kinetic or a Postural Tremor a clinical and electrophysiological study
Movement Disorders, 2002Co-Authors: K C Brennan, Eva C Jurewicz, Blair Ford, Seth L Pullman, Elan D. LouisAbstract:Both Postural and kinetic Tremors may occur in essential Tremor (ET), however the relative contribution of each is not clear. ET has been variably defined with respect to kinetic and Postural Tremors. To examine the relative severity of Postural and kinetic Tremors in ET, 50 ET cases from a clinic and 55 from a community underwent a videotaped Tremor examination. Kinetic and Postural Tremors were rated using a validated clinical rating scale (score range, 0-3). Thirty-one cases also underwent accelerometry to precisely quantify Tremor amplitude. In clinic cases, the mean Postural Tremor rating was 1.25 (S.D., 0.89). The mean kinetic Tremor rating was 52% higher (1.90; S.D., 0.57; P < 0.001). The community cases had similar characteristics. Sixty percent of the 105 cases had Postural Tremor ratings scoring 0 or 1 (no Tremor or low amplitude, intermittent Tremor). In clinic cases, the mean amplitude of Postural Tremor during Tremor analysis was 0.51 mm (S.D., 0.66 mm), and the mean amplitude of kinetic Tremor was 2.91 mm (S.D., 2.11 mm; P < 0.01). Similar values were obtained for community cases. These quantitative data suggest that kinetic Tremor is more severe than Postural Tremor in ET. The majority of cases had mild or absent Postural Tremor. Despite this, ET is defined only as a Postural Tremor in many studies. Our data argue for a more consistent inclusion of kinetic Tremor in diagnostic criteria for ET.
Huiling Tan - One of the best experts on this subject based on the ideXlab platform.
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decoding voluntary movements and Postural Tremor based on thalamic lfps as a basis for closed loop stimulation for essential Tremor
Brain Stimulation, 2019Co-Authors: Huiling Tan, Jean Debarros, Alek Pogosyan, Tipu Z Aziz, Yongzhi Huang, Shouyan Wang, Lars TimmermannAbstract:Abstract Background High frequency Deep brain stimulation (DBS) targeting motor thalamus is an effective therapy for essential Tremor (ET). However, conventional continuous stimulation may deliver unnecessary current to the brain since Tremor mainly affects voluntary movements and sustained postures in ET. Objective We aim to decode both voluntary movements and the presence of Postural Tremor from the Local field potentials (LFPs) recorded from the electrode implanted in motor thalamus for stimulation, in order to close the loop for DBS so that stimulation could be delivered on demand, without the need for peripheral sensors or additional invasive electrodes. Methods LFPs from the motor thalamus, surface electromyographic (EMG) signals and/or behavioural measurements were simultaneously recorded in seven ET patients during temporary lead externalisation 3–5 days after the first surgery for DBS when they performed different voluntary upper limb movements. Nine different patients were recorded during the surgery, when they were asked to lift their arms to trigger Postural Tremor. A machine learning based binary classifier was used to detect voluntary movements and Postural Tremor based on features extracted from thalamic LFPs. Results Cross-validation demonstrated that both voluntary movements and Postural Tremor can be decoded with an average sensitivity of 0.8 and false detection rate of 0.2. Oscillatory activities in the beta frequency bands (13–23 Hz) and the theta frequency bands (4–7 Hz) contributed most to the decoding of movements and Postural Tremor, respectively, though incorporating features in different frequency bands using a machine learning approach increased the accuracy of decoding.
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decoding voluntary movements and Postural Tremor based on thalamic lfps for closed loop stimulation for essential Tremor
bioRxiv, 2018Co-Authors: Huiling Tan, Lars Timmermann, Jean Debarros, Alek Pogosyan, Tipu Z Aziz, Yongzhi Huang, Shouyan Wang, Veerle Visservandewalle, David J Pedrosa, Alexander L GreenAbstract:High frequency deep brain stimulation (DBS) targeting motor thalamus is an effective therapy for essential Tremor (ET). However, conventional continuous stimulation may deliver unnecessary current to the brain since Tremor mainly affects voluntary movements and sustained postures in ET. We recorded LFPs from the motor thalamus, surface electromyographic (EMG) signals and/or behavioural measurements in seven ET patients during temporary lead externalization after the first surgery for DBS when they performed different voluntary upper limb movements and in nine more patients during the surgery, when they were asked to lift their arms to trigger Postural Tremor. We show that both voluntary movements and Postural Tremor can be decoded based on features extracted from thalamic LFPs using a machine learning based binary classifier. This information can be used to close the loop for DBS so that stimulation could be delivered on demand, without the need for peripheral sensors or additional invasive electrodes.
Daniel M Corcos - One of the best experts on this subject based on the ideXlab platform.
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effects of subthalamic nucleus stimulation and medication on resting and Postural Tremor in parkinson s disease
Brain, 2004Co-Authors: Molly M Sturman, David E Vaillancourt, Leo Verhagen Metman, Roy A E Bakay, Daniel M CorcosAbstract:Summary Deep brain stimulation (DBS) of the subthalamic nucleus (STN) and antiparkinsonian medication have proved to be effective treatments for Tremor in Parkinson’s disease. To date it is not known how and to what extent STN DBS alone and in combination with antiparkinsonian medication alters the pathophysiology of resting and Postural Tremor in idiopathic Parkinson’s disease. The purpose of this study was to examine the effects of STN DBS and antiparkinsonian medication on the neurophysiological characteristics of resting and Postural hand Tremor in Parkinson’s disease. Resting and Postural hand Tremor were recorded using accelerometry and surface electromyography (EMG) from 10 Parkinson’s disease patients and 10 matched control subjects. The Parkinson’s disease subjects were examined under four treatment conditions: (i) off treatment; (ii) STN DBS; (iii) medication; and (iv) medication plus STN DBS. The amplitude, EMG frequency, regularity, and 1–8 Hz Tremor–EMG coherence were analysed. Both STN DBS and medication reduced the amplitude, regularity and Tremor–EMG coherence, and increased the EMG frequency of resting and Postural Tremor in Parkinson’s disease. STN DBS was more effective than medication in reducing the amplitude and increasing the frequency of resting and Postural Tremor to healthy physiological levels. These findings provide strong evidence that effective STN DBS normalizes the amplitude and frequency of Tremor. The findings suggest that neural activity in the STN is an important modulator of the neural network(s) responsible for both resting and Postural Tremor genesis in Parkinson’s disease.