Valery Legrain

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Laser evoked potentials (LEPs) are brain responses to activation of skin nociceptors by laser heat stimuli. LEPs consist of three components: N1, N2, and P2. Previous reports have suggested that in contrast to earlier activities (N1), LEPs responses after 230-250 ms (N2-P2) are modulated by attention to painful laser stimuli. However, the experimental(More)
Neuroimaging and neurophysiological studies have shown that nociceptive stimuli elicit responses in an extensive cortical network including somatosensory, insular and cingulate areas, as well as frontal and parietal areas. This network, often referred to as the "pain matrix", is viewed as representing the activity by which the intensity and unpleasantness(More)
READ – Unité de Réadaptation et de Médecine physique, Université catholique de Louvain, Louvain-la-Neuve & Brussels, 1200 Brussels, Belgium Department of Experimental-Clinical and Health Psychology, Universiteit Gent, Ghent, Belgium Centre for Pain Research, University of Bath, UK Division of Brain, Imaging and Behaviour, Toronto Western Research Institute,(More)
Infantile acute hemorrhagic edema of the skin is not included as a separate entity in the current English-language literature as it is in continental Europe. Therefore we have attempted to clarify the nosologic position of acute hemorrhagic edema among cutaneous vasculitides in children, on the basis of our experience in 10 cases. Our study confirms that(More)
OBJECTIVE Recent laser evoked potential (LEP) studies showed that unattended rare intensity-deviant nociceptive stimuli enhance the LEP vertex positivity P2 ('P400 effect'). It was hypothesized to reflect an involuntary switch of attention to nociceptive events. If true the P400 effect (1) should be produced when attention is focused on a task in another(More)
The autonomic nervous system (ANS) reacts to nociceptive stimulation during sleep, but whether this reaction is contingent to cortical arousal, and whether one of the autonomic arms (sympathetic/parasympathetic) predominates over the other remains unknown. We assessed ANS reactivity to nociceptive stimulation during all sleep stages through heart rate(More)
Laser evoked potentials (LEPs) are electrical brain responses to nociceptive heat stimuli. In a recent study [Legrain, V., Guérit, J.M., Bruyer, R. and Plaghki, L., Pain, 99 (2002) 21-39.], we found that amplitude at approximately 400 ms was increased by rare intensity deviant nociceptive stimuli (P400 effect). In that study, laser stimuli were randomly(More)
Pain can involuntarily capture attention and disrupt pain-unrelated cognitive activities. The brain mechanisms of these effects were explored by laser- and visual-evoked potentials. Consecutive nociceptive laser stimuli and visual stimuli were delivered in pairs. Subjects were instructed to ignore nociceptive stimuli while performing a task on visual(More)
We studied behavioural responses and 32-channel brain potentials to nociceptive stimuli during all-night sleep in 12 healthy subjects, using sequences of thermal laser pulses delivered over the dorsum of the hand. Laser stimuli less than 20 dB over perception threshold had clear awakening properties, in accordance with the intrinsic threatening value of(More)
A retrospective study was carried out in 40 infants, age 1 to 24 months, with urticaria. Acute urticaria was seen most frequently (85%), followed by recurrent (10%) and chronic disease (5%). Several clinical features such as frequency of angioedema and hemorrhagic lesions appeared to be specific to urticaria in infants. An underlying cause was identified or(More)