Postural correlates with painful situations

Abstract

Background: Emotional context may play a crucial role in movement production. According to simulation theories, emotional states affect motor systems. The aim of this study was to compare postural responses assessed by posturography and electromyography when subjects were instructed to imagine themselves in a painful or a non-painful situation.Methods: Twenty-nine subjects (22.3 ± 3.7 years) participated in this study. While standing quietly on a posturographic platform, they were instructed to imagine themselves in a painful or non-painful situation. Displacement of the center of pressure (COP), leg muscle electromyographic activity, heart rate, and electrodermal activity were assessed in response to painful and non-painful situations.Results: The anteroposterior path was shorter (p < 0.05) when subjects imagined themselves in a painful situation (M = 148.0 ± 33.4 mm) compared to a non-painful situation (158.2 ± 38.7 mm). Higher tibialis anterior (TA) activity (RMS-TA = 3.38 ± 1.95% vs. 3.24 ± 1.85%; p < 0.001) and higher variability of soleus (SO) activity (variation coefficient of RMS-SO = 13.5 ± 16.2% vs. M = 9.0 ± 7.2%; p < 0.05) were also observed in painful compared to non-painful situations. No significant changes were observed for other physiological data.Conclusion: This study demonstrates that simulation of painful situations induces changes in postural control and leg muscle activation compared to non-painful situations, as increased stiffness was demonstrated in response to aversive pictures in accordance with previous results.

Seeing fearful body language rapidly freezes the observer's motor cortex

“…Moreover, they concur with studies in humans reporting that the observer's body freezes during passive observation of aversive and arousing stimuli (Azevedo et al, 2005;Eerland, Guadalupe, Franken, & Zwaan, 2012;Facchinetti, Imbiriba, Azevedo, Vargas, & Volchan, 2006;Hillman, Rosengren, & Smith, 2004;Horslen & Carpenter, 2011;Lelard et al, 2013;Roelofs, Hagenaars, & Stins, 2010;Stins et al, 2011). Remarkably, our study significantly expands these observations by revealing a possible early cortical mechanism for implementing these motor reactions to emotional and, in particular, fear-related cues in humans.…”

Efeito ansiogênico do medo de quedas sobre o controle postural antecipatório

“…O estudo evidenciou que ocorre diminuição na amplitude e frequência de deslocamento do CP no sentido AP na medida em que aumenta o nível de ameaça postural (plataforma elevada) [12]. Esta diminuição na oscilação postural provavelmente está relacionada com o fenômeno de congelamento postural [35,36], que é observado em participantes que visualizam imagens desagradáveis (pessoas multiladas ou com dor) [35,37,38]. Recentemente, foi eviden-ciado que estudantes submetidos a eventos ansiogênicos (como o período de provas) apresentaram mudanças no controle postural ortostático [39].…”

Thinking with other minds

“…The ability to simulate another person's emotional response in a particular situation could be the basis for the development of empathic skills (Meltzoff & Decety 2003) and the instruction to adopt another person's perspective modulates pain rating according to the affective link between the observer and the individual experiencing the outcome (Singer et al 2006). In a first study (Lelard et al 2013), we used posturography to record differential postural responses when participants were instructed to imagine themselves in a painful or non-painful situation within the functional context of empathy for pain. This study demonstrated for the first time a stiffening response to pain visual stimulation, showing that postural responses were dependent of the perceived pain during the induced simulation process.…”