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1.
Cerebrovasc Dis ; 29(6): 571-5, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-20375500

RESUMEN

BACKGROUND: The purpose of this study was to determine the incidence and clinical correlation of intracranial hemorrhages (ICHs) detected by 3-tesla gradient echo T(2)*-weighted images after intravenous recombinant tissue plasminogen activator (rt-PA) administration. METHODS: We included 43 consecutive patients with anterior-circulation ischemia who underwent MRI studies before and after thrombolysis. Each hemorrhage was classified as a hemorrhagic infarction (HI) or parenchymal hemorrhage (PH) according to the European Cooperative Acute Stroke Study definition. The clinical outcome was defined as an improvement (> or =4-point reduction) or deterioration (> or =4-point increase) based on a comparison between the initial and the 30-day NIHSS scores. RESULTS: The incidence of ICHs was 58%, and the HI rate was 52%; both were higher than the rates reported in the literature. Most of the patients with HI improved clinically, and these patients had second MRAs that showed recanalization. None of the patients with PH demonstrated improvement. CONCLUSIONS: Three-tesla MRI may reveal a higher frequency of HI type hemorrhages than lower-field MRIs, and HI may be a predictor of good recovery by reflecting the presence of recanalization. The rate of PH in our study was low compared to other studies, probably due to the lower dosage of rt-PA.


Asunto(s)
Hemorragia Cerebral/epidemiología , Hemorragia Cerebral/patología , Imagen Eco-Planar/métodos , Terapia Trombolítica/efectos adversos , Activador de Tejido Plasminógeno/efectos adversos , Enfermedad Aguda , Anciano , Encéfalo/patología , Isquemia Encefálica/complicaciones , Hemorragia Cerebral/etiología , Imagen de Difusión por Resonancia Magnética , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Inyecciones Intravenosas , Masculino , Persona de Mediana Edad , Proteínas Recombinantes , Accidente Cerebrovascular/complicaciones , Accidente Cerebrovascular/tratamiento farmacológico , Accidente Cerebrovascular/etiología , Activador de Tejido Plasminógeno/uso terapéutico
2.
J Neurosci ; 28(16): 4201-9, 2008 Apr 16.
Artículo en Inglés | MEDLINE | ID: mdl-18417699

RESUMEN

We compared the metabolic and neurovascular effects of levodopa (LD) therapy for Parkinson's disease (PD). Eleven PD patients were scanned with both [15O]-H2O and [18F]-fluorodeoxyglucose positron emission tomography in the unmedicated state and during intravenous LD infusion. Images were used to quantify LD-mediated changes in the expression of motor- and cognition-related PD covariance patterns in scans of cerebral blood flow (CBF) and cerebral metabolic rate for glucose (CMR). These changes in network activity were compared with those occurring during subthalamic nucleus (STN) deep brain stimulation (DBS), and those observed in a test-retest PD control group. Separate voxel-based searches were conducted to identify individual regions with dissociated treatment-mediated changes in local cerebral blood flow and metabolism. We found a significant dissociation between CBF and CMR in the modulation of the PD motor-related network by LD treatment (p < 0.001). This dissociation was characterized by reductions in network activity in the CMR scans (p < 0.003) occurring concurrently with increases in the CBF scans (p < 0.01). Flow-metabolism dissociation was also evident at the regional level, with LD-mediated reductions in CMR and increases in CBF in the putamen/globus pallidus, dorsal midbrain/pons, STN, and ventral thalamus. CBF responses to LD in the putamen and pons were relatively greater in patients exhibiting drug-induced dyskinesia. In contrast, flow-metabolism dissociation was not present in the STN DBS treatment group or in the PD control group. These findings suggest that flow-metabolism dissociation is a distinctive feature of LD treatment. This phenomenon may be especially pronounced in patients with LD-induced dyskinesia.


Asunto(s)
Circulación Cerebrovascular/efectos de los fármacos , Levodopa/uso terapéutico , Enfermedad de Parkinson/tratamiento farmacológico , Enfermedad de Parkinson/metabolismo , Anciano , Velocidad del Flujo Sanguíneo/efectos de los fármacos , Velocidad del Flujo Sanguíneo/fisiología , Circulación Cerebrovascular/fisiología , Estimulación Encefálica Profunda/métodos , Humanos , Levodopa/farmacología , Persona de Mediana Edad , Enfermedad de Parkinson/fisiopatología , Tomografía de Emisión de Positrones/métodos , Núcleo Subtalámico/efectos de los fármacos , Núcleo Subtalámico/metabolismo
3.
Clin Neurophysiol ; 119(11): 2538-45, 2008 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-18835216

RESUMEN

OBJECTIVE: To optimize the clinical uses of repetitive transcranial magnetic stimulation (rTMS), we compared the effects of rTMS on somatosensory-evoked potentials (SEPs) and regional cerebral blood flow (rCBF) using different phases (monophasic vs. biphasic) or frequencies (0.2Hz vs. 0.8Hz) of stimulation. METHODS: In the first experiment, different phases were compared (0.2Hz monophasic vs. 0.2Hz biphasic). Biphasic 1Hz or sham condition served as controls. The second experiment was to explore the effect of frequencies (0.2Hz vs. 0.8Hz) using the monophasic stimulation. Substhreshold TMS was applied 250 times over the left premotor cortex. Single photon emission computed tomography (SPECT) was performed before and after monophasic 0.2Hz or biphasic 1Hz rTMS. RESULTS: Monophasic rTMS of both 0.2 and 0.8Hz significantly increased the ratio of N30 amplitudes as compared with sham rTMS, whereas biphasic stimulation showed no significant effects. SPECT showed increased rCBF in motor cortices after monophasic 0.2Hz rTMS, but not after biphasic 1Hz stimulation. CONCLUSIONS: Monophasic rTMS exerted more profound effects on SEPs and rCBF than biphasic rTMS over the premotor cortex. SIGNIFICANCE: Monophasic rTMS over the premotor cortex could be clinically more useful than biphasic rTMS.


Asunto(s)
Mapeo Encefálico , Potenciales Evocados Somatosensoriales/fisiología , Corteza Somatosensorial , Tomografía Computarizada de Emisión de Fotón Único , Estimulación Magnética Transcraneal , Adulto , Análisis de Varianza , Circulación Cerebrovascular/fisiología , Circulación Cerebrovascular/efectos de la radiación , Relación Dosis-Respuesta en la Radiación , Estimulación Eléctrica , Femenino , Humanos , Masculino , Corteza Somatosensorial/irrigación sanguínea , Corteza Somatosensorial/diagnóstico por imagen , Corteza Somatosensorial/fisiología , Factores de Tiempo , Adulto Joven
5.
Brain ; 129(Pt 10): 2667-78, 2006 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-16844713

RESUMEN

It has been proposed that deep brain stimulation (DBS) of the subthalamic nucleus (STN DBS) and dopaminergic therapy ameliorate the symptoms of Parkinson's disease through similar functional mechanisms. We examined this notion using PET to compare the metabolic effects of these treatment approaches. Nine Parkinson's disease patients (age 61.7 +/- 11.1 years) were scanned ON and OFF STN stimulation and nine others (age 60.0 +/- 9.3 years) were scanned ON and OFF an individual titrated intravenous levodopa infusion. The two treatment groups were matched for baseline disease severity as well as clinical response to therapy. Similarities and differences in the effects of treatment on regional metabolism were assessed using statistical parametric mapping (SPM). In addition, we used network analysis to assess the effect of therapy on the expression of an abnormal Parkinson's disease-related spatial covariance pattern (PDRP). We found that both STN DBS and levodopa therapy were associated with significant (P < 0.001) metabolic reductions in the putamen/globus pallidus, sensorimotor cortex and cerebellar vermis, as well as increases in the precuneus (BA 7). The metabolic effects of the two interventions differed in the STN and medial prefrontal cortex, with relative increases with stimulation in the former structure and decreases in the latter. Network quantification disclosed reductions in PDRP activity with both interventions, which correlated with clinical improvement (P < 0.05). The degree of network modulation by therapy did not differ significantly for the two treatment approaches (P > 0.6). These findings support the results of previous imaging studies indicating that effective symptomatic therapies for Parkinson's disease involve a common mechanism. The modulation of pathological brain networks is a critical feature of the treatment response in parkinsonism.


Asunto(s)
Estimulación Encefálica Profunda , Enfermedad de Parkinson/terapia , Núcleo Subtalámico/fisiopatología , Adulto , Anciano , Análisis de Varianza , Antiparkinsonianos/uso terapéutico , Cerebelo/metabolismo , Femenino , Fluorodesoxiglucosa F18 , Globo Pálido/metabolismo , Glucosa/metabolismo , Humanos , Levodopa/uso terapéutico , Modelos Lineales , Masculino , Persona de Mediana Edad , Corteza Motora/metabolismo , Pruebas Neuropsicológicas , Enfermedad de Parkinson/diagnóstico por imagen , Enfermedad de Parkinson/metabolismo , Tomografía de Emisión de Positrones , Putamen/metabolismo , Núcleo Subtalámico/metabolismo , Resultado del Tratamiento
6.
J Med Invest ; 52 Suppl: 272-9, 2005 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-16366514

RESUMEN

Functional neuroimaging, such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), provides a valuable technique for detecting regional changes in brain metabolic activity associated with human disease. These techniques have been applied in different dystonic disorders including primary generalized dystonia and dopa-responsive dystonia (DRD), as well as focal dystonic syndromes such as torticollis, writer's cramp, and blepharospasm. A common finding is abnormality of the basal ganglia and associated outflow pathways to sensorimotor cortex and other regions involved with motor performance. Other recent imaging research has utilized diffusion-based MRI techniques to localize distinct microstructural abnormalities in dystonia patients and gene carriers. This presentation will focus on an integrated approach to understanding the pathophysiology of this genetic and biochemically diverse disorder.


Asunto(s)
Distonía/patología , Imagen por Resonancia Magnética , Tomografía de Emisión de Positrones , Anisotropía , Ganglios Basales/anomalías , Blefaroespasmo/patología , Radioisótopos de Carbono/metabolismo , Estudios de Casos y Controles , Dihidroxifenilalanina/uso terapéutico , Antagonistas de Dopamina/metabolismo , Distonía/diagnóstico por imagen , Distonía/tratamiento farmacológico , Distonía/genética , Distonía/metabolismo , Trastornos Distónicos/patología , Globo Pálido/diagnóstico por imagen , Globo Pálido/metabolismo , Heterocigoto , Humanos , Chaperonas Moleculares/genética , Corteza Motora/diagnóstico por imagen , Corteza Motora/metabolismo , Estudios Prospectivos , Putamen/diagnóstico por imagen , Putamen/metabolismo , Racloprida/metabolismo , Receptores Dopaminérgicos/metabolismo , Tortícolis/patología
7.
Neuroreport ; 14(3): 375-9, 2003 Mar 03.
Artículo en Inglés | MEDLINE | ID: mdl-12634487

RESUMEN

Somatosensory evoked potentials (SEPs) are attenuated or gated during movement. The mechanism for this includes both centrifugal gating of afferent input and competition with other afferents caused by the movement (peripheral gating). Using a paradigm in which the signal for triggering movement is the electric stimulus for SEPs, we studied the gating of SEPs after tibial nerve stimulation prior to foot movement, and compared it with that during counting task. Significant gating was found for P40 component, which distributed centrally and ipsilaterally to the side of the stimulation, whereas the contralateral N40 component showed no changes. Dissociated gating of P40 and N40 indicates multiple generators of these components, in contrast to the previous view of a single generator dipole projecting tangentially. Together with the previous findings in median SEPs, these gating phenomena should represent a general mechanism for sensori-motor integration in preparation for limb movement.


Asunto(s)
Potenciales Evocados Somatosensoriales/fisiología , Movimiento/fisiología , Nervio Tibial/fisiología , Adulto , Mapeo Encefálico , Señales (Psicología) , Estimulación Eléctrica , Pie , Humanos , Masculino , Matemática , Procesos Mentales/fisiología , Persona de Mediana Edad , Sonido
8.
J Neurol ; 251 Suppl 7: vII4-8, 2004 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-15505752

RESUMEN

In this brief article, we report preliminary results from an NIH-funded project to use functional brain imaging to study the natural history of neurodegeneration during the earliest clinical stages of PD. We used positron emission tomography (PET) to measure DAT binding (18F-FPCIT), resting glucose metabolism (18FFDG), and brain activation (H215O) responses in 20 newly diagnosed PD patients. The longitudinal study is being conducted at three time points for each measurement during a 5-year period. The interim results indicate the evolution of abnormal metabolic brain networks and activation responses occurring in parallel with presynaptic nigrostriatal dopamine dysfunction in early PD.


Asunto(s)
Trastornos Parkinsonianos/diagnóstico por imagen , Tomografía de Emisión de Positrones , Anciano , Encéfalo/fisiología , Radioisótopos de Carbono , Progresión de la Enfermedad , Femenino , Fluorodesoxiglucosa F18 , Glucosa/metabolismo , Humanos , Radioisótopos de Yodo , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Movimiento , Pronóstico , Radiofármacos , Tropanos
9.
Toxicon ; 81: 32-6, 2014 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-24495439

RESUMEN

Botulinum neurotoxin type A1 (BoNTs/A1) and type B (BoNT/B) have been used for treating hyperactive muscle contractions. In the present study, we compared the effect of botulinum neurotoxin subtype A2 (6.5 mouse LD50 units A2 neurotoxin, A2NTX) and onabotulinumtoxinA (10 mouse LD50 units BoNT/A1 product) by measuring the compound muscle action potentials (CMAPs) before and after administration. In total, 8 healthy subjects were examined in the present study. A2NTX was injected into the extensor digitorum brevis (EDB) muscle, followed by onabotulinumtoxinA injection into the contralateral EDB muscle after 16 weeks. The CMAP amplitudes from the EDB, abductor hallucis (AH), and abductor digiti minimi pedis (ADM) muscles were measured after each BoNT injection on days 1, 3, 7, 14, 28, 56, 84, and 112 to assess the effect of the toxin. On day 14, both A2NTX and onabotulinumtoxinA produced an approximately 70% decline in EDB CMAP amplitude compared to the baseline values; significant reduction of the CMAP continued through day 112. The CMAP amplitudes from neighboring muscles (AH and ADM) remained intact throughout the study period, except for a slight but significant drop at day 28 after onabotulinumtoxinA injection compared to A2NTX. The current findings indicate that small doses (6.5 units and 10 units) of A2NTX and onabotulinumtoxinA have at least comparable onset and duration of action, although similar clinical effects were obtained with lower dose using A2NTX.


Asunto(s)
Toxinas Botulínicas Tipo A/farmacología , Toxinas Botulínicas Tipo A/administración & dosificación , Electrofisiología , Humanos , Inyecciones Intramusculares , Contracción Muscular/efectos de los fármacos , Fuerza Muscular/efectos de los fármacos , Músculo Esquelético/efectos de los fármacos
11.
Front Neurol ; 3: 58, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22529836

RESUMEN

Although there are some newly developed options to treat dystonia, its medical treatment is not always satisfactory. Zolpidem, an imidazopyridine agonist with a high affinity on benzodiazepine subtype receptor BZ1 (ω1), was found to improve clinical symptoms of dystonia in a limited number of case reports. To investigate what subtype of dystonia is responsive to the therapy, we conducted an open label study to assess the efficacy of zolpidem (5-20 mg) in 34 patients suffering from miscellaneous types of dystonia using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS). Patients were entered into the study if they had been refractory to other medications as evaluated by BFMDRS (no change in the previous two successive visits). After zolpidem therapy, the scores in the patients as a whole were decreased from 7.2 ± 7.9 to 5.5 ± 5.0 (P = 0.042). Patients with generalized dystonia, Meige syndrome/blepharospasm, and hand dystonia improved in the scale by 27.8, 17.8, and 31.0%, respectively, whereas no improvement was found in cervical dystonia patients. Overall response rate among patients were comparable to that of trihexyphenidyl. Zolpidem may be a therapeutic option for generalized dystonia, Meige syndrome, and hand dystonia including musician's. Drowsiness was the dose-limiting factor.

13.
Brain Nerve ; 63(8): 878-83, 2011 Aug.
Artículo en Japonés | MEDLINE | ID: mdl-21817179

RESUMEN

Rehabilitation, a treatment strategy that involves group effort with multiple specialists, roles, and facilities, is widely offered to patients in need. The current rehabilitation strategy is mainly disability oriented, and, in principle, starts from the evaluation of motor function and aims to strengthen the deteriorated function/s. Therefore, this method is very effective for patients with acute diseases. However, the effect of such a rehabilitation strategy on gradually progressive neurodegenerative diseases is not well clarified. In particular, Disability-oriented Rehabilitation has not shown an adequate effect in Parkinson disease, which is associated with psychological stress. In this report, we provide an outline of a new rehabilitation strategy and introduce Mentality-oriented Rehabilitation for patients with Parkinson disease.


Asunto(s)
Enfermedad de Parkinson/rehabilitación , Humanos , Enfermedad de Parkinson/fisiopatología , Enfermedad de Parkinson/psicología , Estrés Psicológico/complicaciones
14.
J Neurol Sci ; 302(1-2): 29-32, 2011 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-21215419

RESUMEN

BACKGROUND: Recently, new electrophysiological ALS criteria incorporating fasciculation potentials (FPs) as evidence for lower motor neuron signs (Awaji Criteria (AC)) was proposed to provide earlier detection of early-stage ALS than revised El Escorial electrophysiological criteria (REEC). However, serial electrophysiological analysis is lacking to ascertain the original intention. The objective for this study was to elucidate whether electrophysiological criteria set for AC detects ALS earlier than REEC's counterpart in patients with ALS. METHODS: Of the 51 patients who were clinically suspected of ALS, 35 patients prospectively received serial electrophysiological studies every 3 months until (1) both electrophysiological AC and REEC criteria were met in more than two muscles representing both of the cervical and lumbosacral segments or (2) either clinically definite or clinically probable REEC criteria was met. The intervals were determined between the initial disease onset and when the respective electrophysiological criteria were met. RESULTS: Electrophysiological diagnostic criteria were met in 94.3% by AC and 40% by REEC at the initial visits. The intervals between the disease onset and the time of meeting the electrophysiological criteria were shorter in AC (mean: 9.0 months) than in REEC (mean: 15.2 months) (P<0.01). Eleven patients who met only AC electrophysiological criteria on the initial study subsequently met REEC electrophysiological criteria with the mean interval of 3.8 months. A higher percentage of bulbar-type ALS (83.3%) met AC than limb-onset ALS (43.4%) (P<0.05). FPs tended to be more frequently observed than fib/psw in the muscles outside the region of initial clinical onset. CONCLUSION: Electrophysiological criteria of AC were met earlier than that of REEC in ALS patients, especially in patients with bulbar onset. Early recognition of ALS by AC may allow effective therapeutic intervention in the early disease stage.


Asunto(s)
Esclerosis Amiotrófica Lateral/diagnóstico , Adulto , Anciano , Anciano de 80 o más Años , Esclerosis Amiotrófica Lateral/fisiopatología , Diagnóstico Precoz , Electromiografía , Fenómenos Electrofisiológicos , Fasciculación/diagnóstico , Fasciculación/fisiopatología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neuronas Motoras/fisiología , Músculo Esquelético/inervación , Músculo Esquelético/fisiopatología , Examen Neurológico , Estándares de Referencia
15.
Rinsho Shinkeigaku ; 51(11): 1114-7, 2011 Nov.
Artículo en Japonés | MEDLINE | ID: mdl-22277501

RESUMEN

Amyotrophic lateral sclerosis (ALS) is characterized by increased excitability of motor neurons and early involvement of large motor fibers that have low electrical thresholds. Despite the advent of new techniques of threshold tracking, exploration of this abnormal excitability has not been straightforward, by tracking at the single target level as previous reported, because of the heterogeneous nature of the disease process among fibers that have variable thresholds. We have assessed different populations of motor axons by tracking at four different target response levels (10, 20, 40 and 60% of maximum compound muscle action potentials), and conducted multiple nerve excitability tests in 27 ALS patients and 23 control subjects. In normal controls, axons with low thresholds have the following characteristics compared to those with high thresholds: greater threshold reduction during depolarizing currents and smaller threshold increase to hyperpolarizing currents, reflecting the order of the fiber size. In contrast, ALS patients lacked these relationships, suggesting increased variability of axonal membrane potentials. Three ALS patients demonstrated changes in threshold electrotonus, consistent with overt membrane depolarization, as seen in ischemic nerves. The variability of motor nerve excitability accounts for fasciculations, confirms previously reported dysfunction of potassium channels, and suggests failure of Na(+)/K(+)pumps, possibly caused by mitochondrial dysfunctions at the early stage.


Asunto(s)
Esclerosis Amiotrófica Lateral/fisiopatología , Potenciales de la Membrana/fisiología , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad
16.
Clin Neurophysiol ; 121(12): 2117-20, 2010 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-20538517

RESUMEN

OBJECTIVE: Slow potassium current (I(Ks)) is important in controlling nerve excitability and its impairment is known in various neurological diseases, including amyotrophic lateral sclerosis (ALS). I(Ks) gives rise to the late subexcitability phase of the recovery cycle, which can be amplified by the use of multiple conditioning pulses. The clinical utility of this technique has not previously been explored. METHODS: Nerve excitability tests, including recovery cycles with single and double conditioning pulses 4ms apart (RC and RC2, respectively) were performed in patients with ALS and control subjects. Late subexcitability values obtained by RC and RC2 were compared in both groups. RESULTS: RC2 was well tolerated in all the subjects. The threshold changes in late subexcitability by RC2 were greater than those by RC in both groups (mean (%): RC, 16.0/13.3; RC2, 34.9/29.4 (Control/ALS)). The ALS group showed lower threshold changes than controls by both methods. Statistical analysis between the ALS and control groups provided smaller P value by RC2 (P=0.018) than by RC (P=0.046). Also, RC2 provided non-significant, but slightly more distinguishing non-parametric rank analysis and greater Area Under the Curve (AUC) by Receiver Operating Characteristic (ROC). RC2 produced more identifiable single peak for late subexcitability than RC in an ALS patient whose late subexcitability was decreased. CONCLUSIONS: Two conditioning stimuli provide greater threshold change for late subexcitability and possibly clearer identification of a peak threshold change than conventional recovery cycle. The findings obtained by this new protocol reinforce the previously reported impairment of I(Ks) in ALS. SIGNIFICANCE: Amplification of I(Ks) by double conditioning pulses is applicable in humans and may help elucidating its clinical significance in pathophysiology in neurological diseases.


Asunto(s)
Potenciales de Acción/fisiología , Esclerosis Amiotrófica Lateral/fisiopatología , Axones/fisiología , Canales de Potasio/fisiología , Adulto , Anciano , Anciano de 80 o más Años , Esclerosis Amiotrófica Lateral/patología , Estudios de Casos y Controles , Estimulación Eléctrica/métodos , Electromiografía/métodos , Femenino , Humanos , Masculino , Persona de Mediana Edad
17.
J Med Invest ; 57(1-2): 109-13, 2010 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-20299749

RESUMEN

In order to investigate the transcallosal effects of repetitive transcranial magnetic stimulation (rTMS), we studied median somatosensory evoked potentials (SEPs) before and after applying monophasic very low-frequency (0.2 Hz) subthreshold rTMS over the right motor cortex. For SEPs, median nerve was stimulated on each side. Sham rTMS served as the control. Twelve healthy subjects participated in this study. After rTMS over the right hemisphere, the amplitude of N34 component in right median SEPs recorded from the left parietal scalp (C3') increased significantly. Other components of right or left median SEPs or those after sham stimulation showed no changes. Monophasic 0.2 Hz subthreshold rTMS over the motor cortex predominantly affected the contralateral SEPs, probably through the transcallosal pathway.


Asunto(s)
Potenciales Evocados Somatosensoriales/fisiología , Corteza Motora/fisiología , Estimulación Magnética Transcraneal , Adulto , Humanos , Masculino
20.
Neuroimage ; 31(2): 699-709, 2006 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-16466934

RESUMEN

Somatosensory-evoked potentials (SEPs) are attenuated by movement. This phenomenon of 'gating' reflects sensorimotor integration for motor control. The frontal N30 component after median nerve stimulation was shown to be reduced in amplitude prior to hand movement. To investigate the mechanism of this sensory gating, we recorded median SEPs immediately before and after application of monophasic very low-frequency (0.2 Hz) repetitive transcranial magnetic stimulation (rTMS) of 250 stimuli over motor cortex (MC), premotor cortex (PMC), or supplementary motor area (SMA) in 9 healthy volunteers. The stimulus intensity for MC or PMC was set 85% of the resting motor threshold for the hand muscle, and that for SMA was at the active motor threshold for the leg muscle. SEPs showed significant increases in amplitudes of the frontal N30 component after PMC stimulation, but not after SMA or MC stimulation. Low-frequency (1 Hz) biphasic stimulation over PMC showed no significant N30 changes in 6 out of 9 subjects tested, indicating the effect being specific for 0.2 Hz monophasic stimulation. To examine the functional anatomy of the N30 change, single photon emission computed tomography was performed immediately before and after monophasic 0.2 Hz rTMS over PMC in all the 9 subjects. Regional cerebral blood flow showed significant increases mainly in PMC and prefrontal cortex, indicating the involvement of these cortical areas in sensory input gating for motor control.


Asunto(s)
Mapeo Encefálico , Encéfalo/fisiología , Circulación Cerebrovascular/fisiología , Potenciales Evocados Somatosensoriales/fisiología , Corteza Motora/fisiología , Flujo Sanguíneo Regional/fisiología , Estimulación Magnética Transcraneal , Adulto , Encéfalo/anatomía & histología , Lateralidad Funcional , Humanos , Masculino
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