References of "Maertens De Noordhout, Alain"
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See detailDelay in the execution of voluntary movement by electrical or magnetic brain stimulation in intact man. Evidence for the storage of motor programs in the brain.
Day, B. L.; Rothwell, J. C.; Thompson, P. D. et al

in Brain : A Journal of Neurology (1989), 112 ( Pt 3)

Experiments were undertaken to study the effect on voluntary movement of an electrical or magnetic stimulus delivered to the brain through the scalp. Subjects were trained to flex or extend their wrist ... [more ▼]

Experiments were undertaken to study the effect on voluntary movement of an electrical or magnetic stimulus delivered to the brain through the scalp. Subjects were trained to flex or extend their wrist rapidly in response to an auditory tone. A single brain stimulus (electrical or magnetic) delivered after the tone and before the usual time of onset of the voluntary reaction could delay the execution of the movement for up to 150 ms, without affecting the pattern of the agonist and antagonist EMG bursts. The delay increased with increasing stimulus intensity and with stimuli which were applied nearer to the usual time of onset of the voluntary reaction. A stimulus given after the onset of the first voluntary agonist EMG burst only delayed the onset of the first antagonist and later EMG bursts. Movement was not delayed when similar experiments were performed with supramaximal stimulation of the median nerve instead of the brain stimulus. The delay following a cortical shock was not due to spinal motoneurons being inaccessible to descending input during the delay period since a second brain stimulus, given in the middle of the delay period, was capable of producing a direct muscle response. Neither could the delay be explained by the brain stimulus altering the time of the subject's intention to respond since a stimulus delivered to one hemisphere before an attempted simultaneous bilateral wrist movement produced a far greater delay of the contralateral than the ipsilateral movement. We suggest that the brain stimulus delayed movement by inhibiting a group of strategically placed neurons in the brain (probably in the motor cortex) which made them unresponsive for a brief period to the command signals they receive which initiate the motor program of agonist and antagonist muscle activity. The results have implications for the issues of the storage of motor programs, internal monitoring of central movement commands and the site of organization of the antagonist EMG burst. [less ▲]

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See detailLa stimulation percutanée électrique et magnetique du cortex moteur chez l'homme. Aspects physiologiques et applications cliniques.
MAERTENS DE NOORDHOUT, Alain ULg; Rothwell, J. C.; Day, B. L. et al

in Revue Neurologique (1989), 145(1), 1-15

The new techniques of percutaneous electric and magnetic stimulation of the motor cortex in conscious man provide a unique opportunity of functional testing of the central motor pathways. These techniques ... [more ▼]

The new techniques of percutaneous electric and magnetic stimulation of the motor cortex in conscious man provide a unique opportunity of functional testing of the central motor pathways. These techniques seem to be safe and no immediate or delayed adverse reactions have been reported. The physiological studies so far performed suggest that the structures which are preferentially excited by these methods are the fast conducting pyramidal neurones. It has been shown that a single cortical stimulus is able to activate spinal motoneurones repeatedly. This phenomenon can easily be explained if the cortical stimulus generates multiple descending volleys in the central motor pathways. By comparison with experiments of stimulation of the exposed motor cortex in animals, it is likely that electric brain stimulation directly activates the axons of the pyramidal neurons at their origin and to a lesser extent also recruits these neurons transsynaptically, via some cortical interneurones. Magnetic stimulation of the brain at the vertex seems to act mostly by the latter mechanism. These different modes of action of the two methods of cortical stimulation explain the latency differences of the EMG responses obtained with either technique. Increased excitability of the spinal motoneurones and the existence of multiple descending volleys in response to a single cortical stimulus result in shortening of the latencies and greater amplitude of the responses recorded during voluntary contraction of the target muscle. Stimulation of the motor cortex has been used in pilot studies conducted on patients suffering from various disorders of the central motor pathways, such as multiple sclerosis, cervical spondylosis, motor neurone disease or stroke. The sensitivity of the technique looks promising. In M.S., the EMG responses usually show an increased central conduction latency, a reduced amplitude and a prolonged duration. The severity of the electrophysiological abnormalities is not very well correlated with clinical weakness, but the correlations seems to be better with hyperreflexia and the presence of brisk finger flexor jerks. The same abnormalities are observed in cervical spondylosis, although to a lesser extent. In motor neurone disease, the responses have a moderately increased latency and their size and duration are markedly reduced. Patients with acute hemispheric stroke usually show absent responses on the contralateral side. Finally, electric cortical stimulation can be very useful in monitoring the functional integrity of descending motor tracts during surgical operations performed on the spinal cord. [less ▲]

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See detailEffects of phosphatidylserine (BC-PS) on aged brain in normal subjects and senile demented patients
Delwaide, Paul ULg; MAERTENS DE NOORDHOUT, Alain ULg; DE PASQUA, Victor ULg et al

in Bazan, N.G;; Horrocks, L. A.; Toffano, G. (Eds.) Phospholipids in the Nervous System: Biochemical and Molecular Pathology. Vol 17 (1989)

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See detailMagnetic stimulation of the motor cortex in early multiple sclerosis
MAERTENS DE NOORDHOUT, Alain ULg; Charlier, Marianne; Delwaide, Paul ULg

in Gonsette, R. E.; Delmotte, P. (Eds.) Recent advances in multiple sclerosis therapy (1989)

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See detailElectric and magnetic stimulation of human motor cortex: surface EMG and single motor unit responses.
Day, B. L.; Dressler, D.; MAERTENS DE NOORDHOUT, Alain ULg et al

in Journal of Physiology (1989), 412

1. The effects of different forms of brain stimulation on the discharge pattern of single motor units were examined using the post-stimulus time histogram (PSTH) technique and by recording the compound ... [more ▼]

1. The effects of different forms of brain stimulation on the discharge pattern of single motor units were examined using the post-stimulus time histogram (PSTH) technique and by recording the compound surface electromyographic (EMG) responses in the first dorsal interosseous (FDI) muscle. Electrical and magnetic methods were used to stimulate the brain through the intact scalp of seven normal subjects. Electrical stimuli were applied either with the anode over the lateral central scalp and the cathode at the vertex (anodal stimulation) or with the anode at the vertex and the cathode lateral (cathodal stimulation). Magnetic stimulation used a 9 cm diameter coil centred at the vertex; current in the coil flowed either clockwise or anticlockwise when viewed from above. 2. Supramotor threshold stimuli produced one or more narrow (less than 2 ms) peaks of increased firing in the PSTH of all thirty-two units studied. Anodal stimulation always produced an early peak. The latencies of the peaks produced by other forms of stimulation, or by high intensities of anodal stimulation, were grouped into four time bands relative to this early peak, at intervals of -0.5 to 0.5, 1-2, 2.5-3.5 and 4-5.5 ms later. Peaks occurring within these intervals are referred to as P0 (the earliest anodal), P1, P2 and P3 respectively. 3. At threshold, anodal stimulation evoked only the P0 peak; at higher intensities, the P2 or more commonly the P3 peak also was recruited. The size of the P0 peak appeared to saturate at high intensities. 4. In five of six subjects, cathodal stimulation behaved like anodal stimulation, except that there was a lower threshold for recruitment of the P2 or P3 peak relative to that of the P0 peak. In the other subject, the P3 peak was recruited before the P0 peak. 5. Anticlockwise magnetic [corrected] stimulation, at threshold, often produced several peaks. These always included a P1 peak, and usually a P3 peak. A P0 peak in the PSTH was never produced by an anticlockwise stimulation [corrected] at intensities which we could explore with the technique. 6. Clockwise magnetic [corrected] stimulation never recruited a P1 peak; in most subjects a P3 peak was recruited first and at higher intensities was accompanied by P0 or P2 peaks. 7. On most occasions when more than one peak was observed in a PSTH, the unit fired in only one of the preferred intervals after each shock. However, double firing was seen in five units when high intensities of stimulation were used.(ABSTRACT TRUNCATED AT 400 WORDS) [less ▲]

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See detailThe Palmomental Reflex in Parkinson's Disease. Comparisons with Normal Subjects and Clinical Relevance
Maertens De Noordhout, Alain ULg; Delwaide, Paul ULg

in Archives of Neurology (1988), 45(4), 425-7

We tested 356 normal subjects and 109 parkinsonian patients for the palmomental reflex. The total incidence of the reflex was 16.3% in normal subjects, increasing with age. In parkinsonian patients, the ... [more ▼]

We tested 356 normal subjects and 109 parkinsonian patients for the palmomental reflex. The total incidence of the reflex was 16.3% in normal subjects, increasing with age. In parkinsonian patients, the overall incidence of the reflex was 71.5%, without clear effect of age. A positive correlation was found between degree of akinesia and incidence as well as intensity of the reflex. In the dyskinetic patients, the reflex was seldom elicited, and, if so, it was small. Modifications of the characteristics of the response could be disclosed in parallel with variations of the patient's clinical status. These findings suggest that the presence of a palmomental reflex in parkinsonian patients could indirectly reflect the decrease of dopaminergic activity in the nigrostriatal pathways. [less ▲]

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See detailDifferential effect of cutanoeous stimuli on responses to electrical or magnetic stimulation of the humain brain
DAY, B. L.; DRESSLER, D.; MAERTENS DE NOORDHOUT, Alain ULg et al

in Journal of Physiology (1988)

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See detailThe role of the sympathetic nervous system in migraine and cluster headache
Schoenen, Jean ULg; MAERTENS DE NOORDHOUT, Alain ULg

in Olesen, J.; Edvinsson, L. (Eds.) Basic Mechanisms of Headache (1988)

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See detailPercutaneous electrical stimulation of lumbosacral roots in man.
MAERTENS DE NOORDHOUT, Alain ULg; Rothwell, J. C.; Thompson, P. D. et al

in Journal of Neurology, Neurosurgery & Psychiatry (1988), 51(2), 174-81

High voltage percutaneous electrical stimulation over the lumbosacral spinal column was used to assess conduction in the cauda equina of 13 normal subjects. Electromyographic activity elicited by such ... [more ▼]

High voltage percutaneous electrical stimulation over the lumbosacral spinal column was used to assess conduction in the cauda equina of 13 normal subjects. Electromyographic activity elicited by such stimulation was recorded from various muscles of the lower limbs. The stimulating cathode was placed over the spinous process of each vertebral body and the anode kept on the iliac crest contralateral to the studied limb. Shifting the cathode in a rostro-caudal direction shortened the response latency in quadriceps, tibialis anterior and extensor digitorum brevis muscles. At moderate intensities (60% maximum), this occurred abruptly when the cathode was placed at levels corresponding to the exit sites from the spinal canal of the roots innervating these muscles. At these intensities, the size of the response in each muscle was largest when the cathode was placed over the conus medullaris or at or below the exit of the motor roots from the spine. Latencies were always equal to or shorter than those obtained with F-wave measurements, suggesting that peripheral motor axons, rather than intraspinal structures were activated by the stimulus. Collision experiments demonstrated that activation occurred at two sites: near the spinal cord and at the root exit site in the vertebral foramina. Recordings made from soleus indicated that larger diameter proprioceptive afferent fibres also could be activated. This technique might have useful clinical applications in the study of both proximal and distal lesions of the cauda equina and provide a non-invasive method of localising such lesions electrophysiologically. [less ▲]

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See detailIntérêt de l'étude de la VCN dans les migraines et les céphalées de tension.
Timsit, M.; Timsit-Berthier, M.; Schoenen, Jean ULg et al

in Revue d'Eléctroencephalographie et de Neurophysiologie Clinique (1987), 17(3), 259-70

The aim of this study was to display the result obtained by the contingent negative variation (CNV) recording in patients suffering from headache. Eighty-five patients were taken into account: 59 with ... [more ▼]

The aim of this study was to display the result obtained by the contingent negative variation (CNV) recording in patients suffering from headache. Eighty-five patients were taken into account: 59 with migraines (M) and 26 with tension headache (TH). A typical CNV pattern (high CNV amplitude with no habituation) differentiated M from TH. Moreover, psychological data were collected through Rorschach ink blot test among 42 headache sufferers (31 M and 11 TH). The typical Rorschach repressive pattern of alexithymia was found as well in M as in TH while CNV amplitude was significantly higher in the 31 M (-25 microV) than in the 11 TH (-19 microV FP less than 0.04). Biochemical data collected among 28 patients (17 M and 11 TH) revealed a positive correlation between CNV amplitude and plasma level of noradrenaline, regardless of the type of headache (r = 0.58; P less than 0.01). Thus, besides psychological factors, catecholaminergic mechanisms seem implicated in the determination of the CNV pattern in migraine. CNV may help the clinician both to specify diagnosis and to decide between the many therapeutic strategies available. [less ▲]

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See detailEffects of beta blockade on contingent negative variation in migraine.
MAERTENS DE NOORDHOUT, Alain ULg; Timsit-Berthier, M.; Timsit, M. et al

in Annals of Neurology (1987), 21(1), 111-112

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See detailA comparison of the effects of cathodal and anodal stimulation of the human motor cortex through the intact scalp
Day, B. L.; MAERTENS DE NOORDHOUT, Alain ULg; Marsden, C. D. et al

in Journal of Physiology (1987), 394

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See detailTemporary interruption of brain processing by an electrical or magnetic cortical shock in man
DAY, B. L.; MAERTENS DE NOORDHOUT, Alain ULg; Marsden, C. D. et al

in Journal of Physiology (1987), 390

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See detailContingent negative variation and efficacy of beta-blocking agents in migraine
Schoenen, Jean ULg; MAERTENS DE NOORDHOUT, Alain ULg; Timsit-Berthier, Martine et al

in Cephalalgia : An International Journal of Headache (1986), 6(4), 229-33

Thirty-three patients with common migraine underwent contingent negative variation (CNV) recordings before receiving prophylactic beta-blocker treatment with either metoprolol (27 patients) or propranolol ... [more ▼]

Thirty-three patients with common migraine underwent contingent negative variation (CNV) recordings before receiving prophylactic beta-blocker treatment with either metoprolol (27 patients) or propranolol (6 patients) at mean daily dosages of 110 mg and 122 mg, respectively. After 3 months the therapeutic efficacy of the beta-blocker was assessed in each patient by means of a global severity score and compared with the initial CNV recordings. The mean clinical improvement was 62%. A significant positive correlation was found between CNV amplitude before prophylaxis and the clinical response to beta-blockers: patients with higher CNV tended to respond better to therapy. Eight of 10 patients with a CNV amplitude higher than -25 microV had a more than 50% reduction of the severity score--that is, a good or excellent response to the beta-blocking agent--whereas only 2 of 9 patients with an amplitude lower than -20 microV had a good response. [less ▲]

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See detailLes algies faciales.
MAERTENS DE NOORDHOUT, Alain ULg; Schoenen, Jean ULg

in Revue Médicale de Liège (1986), 41(9), 342-8

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See detailContingent Negative Variation in Headache
MAERTENS DE NOORDHOUT, Alain ULg; Timsit-Berthier, Martine; Timsit, M. et al

in Annals of Neurology (1986), 19(1), 78-80

Contingent negative variation (CNV), an event-related slow cerebral potential, was analyzed in 79 consecutive headache patients. Compared to normal controls (n = 33), CNV did not differ in tension ... [more ▼]

Contingent negative variation (CNV), an event-related slow cerebral potential, was analyzed in 79 consecutive headache patients. Compared to normal controls (n = 33), CNV did not differ in tension headache (n = 21) or in combined headaches with a predominant tension component (n = 13). The mean amplitude of CNV was significantly (p less than 0.001) increased in migraine (n = 29) as well as in combined headache with predominant migraine (n = 16). All migraineurs were studied between attacks and without prophylactic treatment. CNV may be a useful diagnostic test in headache. Its increased amplitude in migraine might reflect central catecholaminergic hyperactivity. [less ▲]

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See detailOpen pilot trial of ritanserin in parkinsonism.
MAERTENS DE NOORDHOUT, Alain ULg; Delwaide, Paul ULg

in Clinical Neuropharmacology (1986), 9(5), 480-4

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See detailContingent negative variation (CNV) as a diagnostic and physiopathologic tool in headache patients
SCHOENEN, Jean ULg; Maertens De Noordhout, Alain ULg; Timsit-Berthier, M. et al

in Clifford Rose, F. (Ed.) Migraine Proc. (1985)

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