title: Sleep spindles and human cortical nociception: a surface and intracerebral electrophysiological study.
abstract: CONCLUSIONS
  Sleep spindle are usually considered to play a major role in inhibiting sensory inputs. Using nociceptive stimuli in humans, we tested the effect of spindles on behavioural, autonomic and cortical responses in two experiments using surface and intracerebral electroencephalographic recordings. We found that sleep spindles do not prevent arousal reactions to nociceptive stimuli and that autonomic reactivity to nociceptive inputs is not modulated by spindle activity. Moreover, neither the surface sensory, nor the insular evoked responses were modulated by the spindle, as detected at the surface or within the thalamus. The present study comprises the first investigation of the effect of spindles on nociceptive information processing and the results obtained challenge the classical inhibitory effect of spindles.
  Responsiveness to environmental stimuli declines during sleep, and sleep spindles are often considered to play a major role in inhibiting sensory inputs. In the present study, we tested the effect of spindles on behavioural, autonomic and cortical responses to pain, in two experiments assessing surface and intracerebral responses to thermo-nociceptive laser stimuli during the all-night N2 sleep stage. The percentage of arousals remained unchanged as a result of the presence of spindles. Neither cortical nociceptive responses, nor autonomic cardiovascular reactivity were depressed when elicited within a spindle. These results could be replicated in human intracerebral recordings, where sleep spindle activity in the posterior thalamus failed to depress the thalamocortical nociceptive transmission, as measured by sensory responses within the posterior insula. Hence, the assumed inhibitory effect of spindles on sensory inputs may not apply to the nociceptive system, possibly as a result of the specificity of spinothalamic pathways and the crucial role of nociceptive information for homeostasis. Intriguingly, a late scalp response commonly considered to reflect high-order stimulus processing (the 'P3' potential) was significantly enhanced during spindling, suggesting a possible spindle-driven facilitation, rather than attenuation, of cortical nociception.
authors.affiliation: Central Integration of Pain (NeuroPain) Lab - Neuroscience Research Center, INSERM U1028, CNRS UMR5292, Lyon, France.
authors.forename: Léa
authors.initials: L
authors.lastname: Claude
authors.affiliation: Central Integration of Pain (NeuroPain) Lab - Neuroscience Research Center, INSERM U1028, CNRS UMR5292, Lyon, France.
authors.forename: Florian
authors.initials: F
authors.lastname: Chouchou
authors.affiliation: Central Integration of Pain (NeuroPain) Lab - Neuroscience Research Center, INSERM U1028, CNRS UMR5292, Lyon, France.
authors.forename: Germán
authors.initials: G
authors.lastname: Prados
authors.affiliation: Central Integration of Pain (NeuroPain) Lab - Neuroscience Research Center, INSERM U1028, CNRS UMR5292, Lyon, France.
authors.forename: Maïté
authors.initials: M
authors.lastname: Castro
authors.affiliation: Central Integration of Pain (NeuroPain) Lab - Neuroscience Research Center, INSERM U1028, CNRS UMR5292, Lyon, France.
authors.forename: Barbara
authors.initials: B
authors.lastname: De Blay
authors.affiliation: Central Integration of Pain (NeuroPain) Lab - Neuroscience Research Center, INSERM U1028, CNRS UMR5292, Lyon, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Perchet
authors.affiliation: Central Integration of Pain (NeuroPain) Lab - Neuroscience Research Center, INSERM U1028, CNRS UMR5292, Lyon, France.
authors.forename: Luis
authors.initials: L
authors.lastname: García-Larrea
authors.affiliation: Université Lumière Lyon 2, Laboratoire d'Etude des Mécanismes Cognitifs (EMC), Bron, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Mazza
authors.affiliation: Central Integration of Pain (NeuroPain) Lab - Neuroscience Research Center, INSERM U1028, CNRS UMR5292, Lyon, France.|Unité d'Hypnologie, Service de Neurologie Fonctionnelle et d'Épileptologie, Hôpital Neurologique, Hospices Civils de Lyon, Bron, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Bastuji
mesh_terms: D000328:Adult; D001143:Arousal; D002540:Cerebral Cortex / Q000502:physiology*; D005260:Female; D006801:Humans; D066331:Laser-Evoked Potentials; D008297:Male; D009433:Neural Inhibition; D059225:Nociception / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology*; D013788:Thalamus / Q000502:physiology