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1.1 1 xml info:srw/schema/1/mods-v3.2 Liebermann D G author Defrin R author 2009 English BACKGROUND: Nociceptive withdrawal reflexes (NWR) are subject to supraspinal modulation. Therefore, awareness about a noxious stimulation may affect its characteristics. The goal of this study was to investigate the effect of different degrees of awareness on the NWR. METHOD: Eight subjects performed back and forth hand movements from a common starting point towards four visual targets during which NWR was evoked when subjects were either unaware or aware of a noxious stimulation (unaware-NWR and aware-NWR). For the comparison between the NWR under both conditions, onset latencies and kinematic variables were computed respectively from the recorded Biceps Brachii EMG and from the spatial coordinates of hand reflective markers. RESULTS: The onset latency of unaware-NWR (mean+/-SD 73.9+/-13 ms) was significantly shorter than that of the aware-NWR (91.1+/-27 ms, p<0.05). The total duration of the muscular activation was shorter in unaware-NWR than in aware-NWR. The slopes of the tangential velocity-time curves were steeper for unaware-NWR than for aware-NWR (p=0.057). CONCLUSIONS: The results suggest that supraspinal regulation of NWR under different degrees of awareness involves the re-parameterization of selected spatiotemporal aspects of a pre-structured motor response. Adult Arm/*physiopathology Attention *Awareness Cues Female Humans Male Movement *Muscle Contraction Muscle Skeletal/*physiopathology Pain/*physiopathology *Reflex *Startle Reaction PMID:18063387 exported from refbase (https://refbase.nfshost.com/show.php?record=34), last updated on Mon, 31 Dec 2012 14:30:09 +0000 text http://www.ncbi.nlm.nih.gov/pubmed/18063387 http://www.ncbi.nlm.nih.gov/pubmed/18063387 10.1016/j.jelekin.2007.10.006 18063387 Liebermann+Defrin2009 2009 continuing periodical academic journal 19 2 e114-22 1050-6411 1