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Wiest C, Torrecillos F, Tinkhauser G, Pogosyan A, Morgante F, Pereira EA, Tan H. Finely-tuned gamma oscillations: Spectral characteristics and links to dyskinesia. Exp Neurol 2022; 351:113999. [PMID: 35143832 PMCID: PMC7612436 DOI: 10.1016/j.expneurol.2022.113999] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 01/27/2022] [Accepted: 02/02/2022] [Indexed: 01/22/2023]
Abstract
Gamma oscillations comprise a loosely defined, heterogeneous group of functionally different activities between 30 and 100 Hz in the cortical and subcortical local field potential (LFP) of the motor network. Two distinct patterns seem to emerge which are easily conflated: Finely-tuned gamma (FTG) oscillations - a narrowband activity with peaks between 60 and 90 Hz - have been observed in multiple movement disorders and are induced by dopaminergic medication or deep brain stimulation (DBS). FTG has been linked with levodopa or DBS-induced dyskinesias, which makes it a putative biomarker for adaptive DBS. On the other hand, gamma activity can also present as a broad phenomenon (30-100 Hz) in the context of motor activation and dynamic processing. Here, we contrast FTG, either levodopa-induced or DBS-induced, from movement-related broadband gamma synchronisation and further elaborate on the functional role of FTG and its potential implications for adaptive DBS. Given the unclear distinction of FTG and broad gamma in literature, we appeal for more careful separation of the two. To better characterise cortical and subcortical FTG as biomarkers for dyskinesia, their sensitivity and specificity need to be investigated in a large clinical trial.
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Affiliation(s)
- C Wiest
- Medical Research Council Brain Network Dynamics Unit, University of Oxford, Oxford, UK; Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - F Torrecillos
- Medical Research Council Brain Network Dynamics Unit, University of Oxford, Oxford, UK; Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - G Tinkhauser
- Department of Neurology, Bern University Hospital and University of Bern, Bern, Switzerland
| | - A Pogosyan
- Medical Research Council Brain Network Dynamics Unit, University of Oxford, Oxford, UK; Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - F Morgante
- Neurosciences Research Centre, Molecular and Clinical Sciences Institute, St. George's, University of London, London, UK; Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - E A Pereira
- Neurosciences Research Centre, Molecular and Clinical Sciences Institute, St. George's, University of London, London, UK
| | - H Tan
- Medical Research Council Brain Network Dynamics Unit, University of Oxford, Oxford, UK; Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK.
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Zileli M, Osorio-Fonseca E, Konovalov N, Cardenas-Jalabe C, Kaprovoy S, Mlyavykh S, Pogosyan A. Early Management of Cervical Spine Trauma: WFNS Spine Committee Recommendations. Neurospine 2021; 17:710-722. [PMID: 33401852 PMCID: PMC7788428 DOI: 10.14245/ns.2040282.141] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 09/06/2020] [Indexed: 12/12/2022] Open
Abstract
Epidemiology, prevention, early management of cervical spine trauma and it's reduction are the objectives of this review paper. A PubMed and MEDLINE search between 2009 and 2019 were conducted using keywords. Case reports, experimental studies, papers other than English language and and unrelated studies were excluded. Up-to-date information on epidemiology of spine trauma, prevention, early emergency management, transportation, and closed reduction were reviewed and statements were produced to reach a consensus in 2 separate consensus meeting of World Federation of Neurosurgical Societies (WFNS) Spine Committee. The statements were voted and reached a positive or negative consensus using Delphi method. Global incidence of traumatic spinal injury is higher in low- and middle-income countries. The most frequent reasons are road traffic accidents and falls. The incidence from low falls in the elderly are increasing in high-income countries due to ageing populations. Prevention needs legislative, engineering, educational, and social efforts that need common efforts of all society. Emergency care of the trauma patient, transportation, and in-hospital acute management should be planned by implementing detailed protocols to prevent further damage to the spinal cord. This review summarizes the WFNS Spine Committee recommendations on epidemiology, prevention, and early management of cervical spine injuries.
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Affiliation(s)
- Mehmet Zileli
- Department of Neurosurgery, Ege University, Izmir, Turkey
| | | | - Nikolay Konovalov
- N.N. Burdenko National Medical Research Center of Neurosurgery, Moscow, Russian Federation
| | | | - Stanislav Kaprovoy
- N.N. Burdenko National Medical Research Center of Neurosurgery, Moscow, Russian Federation
| | - Sergey Mlyavykh
- Trauma and Orthopedics Institute, Privolzhsky Research Medical University, Nizhniy Novgorod, Russian Federation
| | - Artur Pogosyan
- N.N. Burdenko National Medical Research Center of Neurosurgery, Moscow, Russian Federation
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Wiest C, Tinkhauser G, Pogosyan A, Bange M, Muthuraman M, Groppa S, Baig F, Mostofi A, Pereira EA, Tan H, Brown P, Torrecillos F. Local field potential activity dynamics in response to deep brain stimulation of the subthalamic nucleus in Parkinson's disease. Neurobiol Dis 2020; 143:105019. [PMID: 32681881 PMCID: PMC7115855 DOI: 10.1016/j.nbd.2020.105019] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 06/17/2020] [Accepted: 07/11/2020] [Indexed: 02/06/2023] Open
Abstract
Local field potentials (LFPs) may afford insight into the mechanisms of action of deep brain stimulation (DBS) and potential feedback signals for adaptive DBS. In Parkinson's disease (PD) DBS of the subthalamic nucleus (STN) suppresses spontaneous activity in the beta band and drives evoked resonant neural activity (ERNA). Here, we investigate how STN LFP activities change over time following the onset and offset of DBS. To this end we recorded LFPs from the STN in 14 PD patients during long (mean: 181.2 s) and short (14.2 s) blocks of continuous stimulation at 130 Hz. LFP activities were evaluated in the temporal and spectral domains. During long stimulation blocks, the frequency and amplitude of the ERNA decreased before reaching a steady state after ~70 s. Maximal ERNA amplitudes diminished over repeated stimulation blocks. Upon DBS cessation, the ERNA was revealed as an under-damped oscillation, and was more marked and lasted longer after short duration stimulation blocks. In contrast, activity in the beta band suppressed within 0.5 s of continuous DBS onset and drifted less over time. Spontaneous activity was also suppressed in the low gamma band, suggesting that the effects of high frequency stimulation on spontaneous oscillations may not be selective for pathological beta activity. High frequency oscillations were present in only six STN recordings before stimulation onset and their frequency was depressed by stimulation. The different dynamics of the ERNA and beta activity with stimulation imply different DBS mechanisms and may impact how these activities may be used in adaptive feedback.
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Affiliation(s)
- C Wiest
- Medical Research Council Brain Network Dynamics Unit, University of Oxford, Oxford, UK; Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - G Tinkhauser
- Department of Neurology, Bern University Hospital, Bern, Switzerland
| | - A Pogosyan
- Medical Research Council Brain Network Dynamics Unit, University of Oxford, Oxford, UK; Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - M Bange
- Movement Disorders and Neurostimulation, Biomedical Statistics and Multimodal Signal Processing Unit, Department of Neurology, Mainz University Hospital, Mainz, Germany
| | - M Muthuraman
- Movement Disorders and Neurostimulation, Biomedical Statistics and Multimodal Signal Processing Unit, Department of Neurology, Mainz University Hospital, Mainz, Germany
| | - S Groppa
- Movement Disorders and Neurostimulation, Biomedical Statistics and Multimodal Signal Processing Unit, Department of Neurology, Mainz University Hospital, Mainz, Germany
| | - F Baig
- Medical Research Council Brain Network Dynamics Unit, University of Oxford, Oxford, UK; Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK; Neurosciences Research Centre, Molecular and Clinical Sciences Institute, St. George's, University of London, London, UK
| | - A Mostofi
- Neurosciences Research Centre, Molecular and Clinical Sciences Institute, St. George's, University of London, London, UK
| | - E A Pereira
- Neurosciences Research Centre, Molecular and Clinical Sciences Institute, St. George's, University of London, London, UK
| | - H Tan
- Medical Research Council Brain Network Dynamics Unit, University of Oxford, Oxford, UK; Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - P Brown
- Medical Research Council Brain Network Dynamics Unit, University of Oxford, Oxford, UK; Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - F Torrecillos
- Medical Research Council Brain Network Dynamics Unit, University of Oxford, Oxford, UK; Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK.
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Steiner L, Neumann W, Straub F, Pogosyan A, Herz D, Tan H, Kuhn A, Brown P. P 74 Subthalamic beta dynamics mirror parkinsonian bradykinesia months after neurostimulator implantation. Clin Neurophysiol 2017. [DOI: 10.1016/j.clinph.2017.06.150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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van Wijk BCM, Pogosyan A, Hariz MI, Akram H, Foltynie T, Limousin P, Horn A, Ewert S, Brown P, Litvak V. Localization of beta and high-frequency oscillations within the subthalamic nucleus region. Neuroimage Clin 2017; 16:175-183. [PMID: 28794978 PMCID: PMC5540829 DOI: 10.1016/j.nicl.2017.07.018] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 07/05/2017] [Accepted: 07/22/2017] [Indexed: 12/01/2022]
Abstract
Parkinsonian bradykinesia and rigidity are typically associated with excessive beta band oscillations in the subthalamic nucleus. Recently another spectral peak has been identified that might be implicated in the pathophysiology of the disease: high-frequency oscillations (HFO) within the 150–400 Hz range. Beta-HFO phase-amplitude coupling (PAC) has been found to correlate with severity of motor impairment. However, the neuronal origin of HFO and its usefulness as a potential target for deep brain stimulation remain to be established. For example, it is unclear whether HFO arise from the same neural populations as beta oscillations. We intraoperatively recorded local field potentials from the subthalamic nucleus while advancing DBS electrodes in 2 mm steps from 4 mm above the surgical target point until 2 mm below, resulting in 4 recording sites. Data from 26 nuclei from 14 patients were analysed. For each trajectory, we identified the recording site with the largest spectral peak in the beta range (13–30 Hz), and the largest peak in the HFO range separately. In addition, we identified the recording site with the largest beta-HFO PAC. Recording sites with largest beta power and largest HFO power coincided in 50% of cases. In the other 50%, HFO was more likely to be detected at a more superior recording site in the target area. PAC followed more closely the site with largest HFO (45%) than beta power (27%). HFO are likely to arise from spatially close, but slightly more superior neural populations than beta oscillations. Further work is necessary to determine whether the different activities can help fine-tune deep brain stimulation targeting. LFPs were recorded from multiple sites within and around the subthalamic nucleus. Sites with largest beta and high-frequency oscillations (HFO) were identified. HFO were located slightly more superior than beta oscillations. Phase-amplitude coupling more closely followed the site with largest HFO. This work hints at different neural generators for beta and HFO.
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Affiliation(s)
- B C M van Wijk
- Department of Neurology, Charité - University Medicine Berlin, Berlin, Germany.,Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, London, United Kingdom
| | - A Pogosyan
- Nuffield Department of Clinical Neuroscience, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - M I Hariz
- Unit of Functional Neurosurgery, Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom.,Department of Clinical Neuroscience, Umeå University, Umeå, Sweden
| | - H Akram
- Unit of Functional Neurosurgery, Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom.,Victor Horsley Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, London, United Kingdom
| | - T Foltynie
- Unit of Functional Neurosurgery, Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom
| | - P Limousin
- Unit of Functional Neurosurgery, Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom
| | - A Horn
- Department of Neurology, Charité - University Medicine Berlin, Berlin, Germany.,Berenson-Allen Center for Non-Invasive Brain Stimulation and Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - S Ewert
- Department of Neurology, Charité - University Medicine Berlin, Berlin, Germany.,Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - P Brown
- Nuffield Department of Clinical Neuroscience, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.,Medical Research Council Brain Network Dynamics Unit at the University of Oxford, Oxford, United Kingdom
| | - V Litvak
- Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, London, United Kingdom
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Nowak M, Hinson E, Guerra A, Pogosyan A, van Ede F, Quinn A, Brown P, Stagg C. P168 Modulating cortical excitability of human motor cortex by β- and γ-band transcranial alternating current stimulation (tACS). Clin Neurophysiol 2017. [DOI: 10.1016/j.clinph.2016.10.289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Guerra A, Pogosyan A, Nowak M, Tan H, Ferreri F, Di Lazzaro V, Brown P. 63. Phase dependency of the human primary motor cortex and cholinergic inhibition cancellation during beta tACS. Clin Neurophysiol 2016. [DOI: 10.1016/j.clinph.2016.10.075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Miller S, Rasul F, Matharu M, Pogosyan A, Brown P, Hariz M, Zrinzo L. EHMTI-0282. Deep brain stimulation in chronic cluster headache: lead location, clinical response and neuronal signatures. J Headache Pain 2014. [PMCID: PMC4181985 DOI: 10.1186/1129-2377-15-s1-e19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Little S, Pogosyan A, Kuhn AA, Brown P. β band stability over time correlates with Parkinsonian rigidity and bradykinesia. Exp Neurol 2012; 236:383-8. [PMID: 22572590 PMCID: PMC3400051 DOI: 10.1016/j.expneurol.2012.04.024] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 04/16/2012] [Accepted: 04/23/2012] [Indexed: 11/26/2022]
Abstract
Abnormal oscillatory activity in the basal ganglia is increasingly implicated in the pathophysiology of Parkinson's disease. Such activity is recorded in patients in the form of oscillations in the local field potential (LFP) picked up in the subthalamic nucleus. Previous studies have focused on correlations between features of the time averaged power or amplitude spectrum of the LFP and the clinical state, either off medication or in response to levodopa. However, average spectral densities do not take account of time variant spectral properties and we hypothesised that these dynamic properties of the spectrum of the LFP would contain additional information about clinical state. Here we assess the variability in LFP amplitude over time using the coefficient of variation (CV), evaluating this with regard to clinical state off medication and in response to levodopa in two datasets. The CV of activity in the high beta frequency band was found to be correlated with clinical state off levodopa (rho=-0.59, p<0.001) and this was shown to be complementary, rather than redundant, to spectral amplitude in a multiple regression analysis, selective for rigidity-bradykinesia and highly focal. Similarly, a strong correlation was found between change in clinical scores and change in high beta CV following levodopa (rho=-0.66, p=0.004). This too was selective for rigidity-bradykinesia and non-redundant to spectral power in a multiple regression model. Our results indicate that temporal stability in the beta band is correlated with rigidity-bradykinesia. It is suggested that loss of beta reactivity is deleterious to basal ganglia function over and above any concomitant change in absolute level of beta synchrony. The CV of LFP beta band amplitude may potentially provide an additional index of clinical state suitable for feedback control in closed loop stimulation therapy.
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Affiliation(s)
- S Little
- Department of Clinical Neurology, Oxford University, 6th Floor, West wing, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK.
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Anzak A, Pogosyan A, Tan H, Foltynie T, Limousin, P, Zrinzo L, Hariz M, Ashkan K, Thevathasan W, Bogdanovic M, Green A, Aziz T, Brown P. 3.320 INSIGHTS INTO THE MECHANISM OF PARADOXICAL KINESIA FROM SUBTHALAMIC NUCLEUS RECORDINGS IN PARKINSON'S DISEASE. Parkinsonism Relat Disord 2012. [DOI: 10.1016/s1353-8020(11)70954-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Eusebio A, Thevathasan W, Doyle Gaynor L, Pogosyan A, Bye E, Foltynie T, Zrinzo L, Ashkan K, Aziz T, Brown P. Deep brain stimulation can suppress pathological synchronisation in parkinsonian patients. J Neurol Neurosurg Psychiatry 2011; 82:569-73. [PMID: 20935326 PMCID: PMC3072048 DOI: 10.1136/jnnp.2010.217489] [Citation(s) in RCA: 278] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Although deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a highly effective therapeutic intervention in severe Parkinson's disease, its mechanism of action remains unclear. One possibility is that DBS suppresses local pathologically synchronised oscillatory activity. METHODS To explore this, the authors recorded from DBS electrodes implanted in the STN of 16 patients with Parkinson's disease during simultaneous stimulation (pulse width 60 μs; frequency 130 Hz) of the same target using a specially designed amplifier. The authors analysed data from 25 sides. RESULTS The authors found that DBS progressively suppressed peaks in local field potential activity at frequencies between 11 and 30 Hz as voltage was increased beyond a stimulation threshold of 1.5 V. Median peak power had fallen to 54% of baseline values by a stimulation intensity of 3.0 V. CONCLUSION The findings suggest that DBS can suppress pathological 11-30 Hz activity in the vicinity of stimulation in patients with Parkinson's disease. This suppression occurs at stimulation voltages that are clinically effective.
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Affiliation(s)
- A Eusebio
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, London, UK
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Gaynor LMFD, Kühn AA, Dileone M, Litvak V, Eusebio A, Pogosyan A, Androulidakis AG, Tisch S, Limousin P, Insola A, Mazzone P, Di Lazzaro V, Brown P. Suppression of beta oscillations in the subthalamic nucleus following cortical stimulation in humans. Eur J Neurosci 2008; 28:1686-95. [PMID: 18657185 PMCID: PMC2695156 DOI: 10.1111/j.1460-9568.2008.06363.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It is unclear how subthalamic nucleus activity is modulated by the cerebral cortex. Here we investigate the effect of transcranial magnetic stimulation (TMS) of the cortex on oscillatory subthalamic local field potential activity in the 8–35 Hz (alpha/beta) band, as exaggerated synchronization in this band is implicated in the pathophysiology of parkinsonism. We studied nine patients with Parkinson’s disease (PD) to test whether cortical stimulation can modulate synchronized oscillations in the human subthalamic nucleus. With patients at rest, single-pulse TMS was delivered every 5 s over each primary motor area and supplementary motor area at intensities of 85–115% resting motor threshold. Subthalamic local field potentials were recorded from deep brain stimulation electrodes implanted into this nucleus for the treatment of PD. Motor cortical stimulation suppressed beta activity in the subthalamic nucleus from ∼0.2 to 0.6 s after TMS (repeated measures anova; main effect of time, P<0.01; main effect of side, P=0.03), regardless of intensity. TMS over the supplementary motor area also reduced subthalamic beta activity at 95% (P=0.05) and 115% resting motor threshold (P=0.01). The oscillatory activity decreased to 80 ± 26% of baseline (averaged across sites and stimulation intensities). Suppression with subthreshold stimuli confirmed that these changes were centrally driven and not due to peripheral afference. The results may have implications for mechanisms underlying the reported therapeutic benefits of cortical stimulation.
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Affiliation(s)
- L M F Doyle Gaynor
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, London, UK
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Kuhn A, Kempf F, Bruecke C, Chen Z, Nuttin B, Trottenberg T, Kupsch A, Schneider G, Hariz M, Limousin P, Pogosyan A, Brown P. P22.8 Deep brain stimulation induces suppression of oscillatory β activity in the subthalamic nucleus in PD patients. Clin Neurophysiol 2006. [DOI: 10.1016/j.clinph.2006.06.425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Klostermann F, Kühn AA, Wahl M, Marzinzik F, Pogosyan A, Kupsch A, Curio G, Brown P. Differential EEG Synchronization at Thalamic, Subthalamic and Cortical Levels during a Choice-Reaction Time Task. KLIN NEUROPHYSIOL 2004. [DOI: 10.1055/s-2004-832048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Abstract
BACKGROUND The mechanisms behind motor recovery from stroke are not clearly understood. Functional imaging studies have demonstrated task-related brain activation in several motor areas, but few studies have attempted to correlate this with stroke outcome. Moreover, these studies have focused on how motor areas may individually contribute to compensation. Here, the authors investigate whether different cortical areas interact to form dynamic assemblies that may then compensate for disability. METHODS The authors investigated corticocortical coherence in 16 healthy subjects and 25 patients with chronic stroke involving one cerebral hemisphere and having varying degrees of motor recovery. Scalp EEG was recorded at rest and while right-handed subjects performed a unimanual grip task. The degree of functional recovery after stroke was assessed using a range of outcome measures. RESULTS Compared with healthy subjects, hand-related asymmetries in task-related EEG-EEG coherence were increased between mesial and lateral frontal regions of the affected hemisphere, over mesial frontal regions, and over lateral frontal areas of the unaffected hemisphere when patients with stroke gripped with their affected hand. Mesial hand-related asymmetries in task-related power and coherence were negatively correlated with recovery. CONCLUSION Increases in task-related coupling between cortical areas may dynamically compensate for brain damage after stroke. Some of this increased coupling, particularly that over mesial frontal areas, decreases as patients make a functional recovery.
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Affiliation(s)
- L H A Strens
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
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Grosse P, Guerrini R, Parmeggiani L, Bonanni P, Pogosyan A, Brown P. Abnormal corticomuscular and intermuscular coupling in high-frequency rhythmic myoclonus. Brain 2003; 126:326-42. [PMID: 12538401 DOI: 10.1093/brain/awg043] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Frequency analysis may have some advantages over back-averaging in the neurophysiological assessment of patients with suspected cortical myoclonus in whom myoclonic EMG bursts repeat rhythmically at high frequency. However, the clinical utility of EEG-EMG coherence and related EMG-EMG coherence is not established. Equally, there is an incomplete understanding of the physiology of the systems contributing to the coherence evident between signals in cortical myoclonus. Here we address these issues in an investigation of EEG-EMG and EMG-EMG coupling in proximal and distal muscles of the upper extremities in nine patients with multifocal high frequency rhythmic myoclonus due to non-progressive conditions. We found exaggerated coherence between EEG and contralateral EMG and between pairs of ipsilateral EMG signals. The results of frequency analysis of EMG-EMG mirrored those for EEG-EMG, but the former technique was superior in distinguishing a pathologically exaggerated common drive in distal upper limb muscles. Both techniques were more sensitive than back-averaging. Frequency analysis also revealed important disparities between proximal and distal upper limb muscles. In the latter case, the functional coupling between cortex and muscle was dominated by efferent processes. In contrast, there was considerable inter-individual variation in the extent to which EEG-EMG and EMG-EMG coupling in proximal muscles reflected afferent and efferent loops. Thus, the processes sustaining myoclonic discharges may differ for proximal and distal muscles and between patients.
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Affiliation(s)
- P Grosse
- Sobell Department of Clinical Neurophysiology, Institute of Neurology, London, UK.
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