Pelosin Elisa, Bisio Ambra, Pozzo Thierry, Lagravinese Giovanna, Crisafulli Oscar, Marchese Roberta, Abbruzzese Giovanni, Avanzino Laura
Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Maternal Child Health, University of Genoa, Genoa, Italy.
Ospedale Policlinico San Martino, Istituto di Ricovero e Cura a Carattere Scientifico per l'Oncologia, Genoa, Italy.
Front Neurol. 2018 Mar 1;9:105. doi: 10.3389/fneur.2018.00105. eCollection 2018.
Postural reactions can be influenced by concomitant tasks or different contexts and are modulated by a higher order motor control. Recent studies investigated postural changes determined by motor contagion induced by action observation (chameleon effect) showing that observing a model in postural disequilibrium induces an increase in healthy subjects' body sway. Parkinson's disease (PD) is associated with postural instability and impairments in cognitively controlled balance tasks. However, no studies investigated if viewing postural imbalance might influence postural stability in PD and if patients are able to inhibit a visual postural perturbation. In this study, an action observation paradigm for assessing postural reaction to motor contagion in PD subjects and healthy older adults was used. Postural stability changes were measured during the observation of a static stimulus (control condition) and during a point-light display of a gymnast balancing on a rope (biological stimulus). Our results showed that, during the observation of the biological stimulus, sway area and antero-posterior and medio-lateral displacements of center of pressure significantly increased only in PD participants, whereas correct stabilization reactions were present in elderly subjects. These results demonstrate that PD leads to a decreased capacity to control automatic imitative tendencies induced by motor contagion. This behavior could be the consequence either of an inability to inhibit automatic imitative tendencies or of the cognitive load requested by the task. Whatever the case, the issue about the ability to inhibit automatic imitative tendencies could be crucial for PD patients since it might increase falls risk and injuries.
姿势反应会受到伴随任务或不同情境的影响，并由更高层次的运动控制进行调节。最近的研究调查了由动作观察（变色龙效应）引发的运动感染所决定的姿势变化，结果显示，观察处于姿势失衡状态的模型会导致健康受试者的身体摇摆增加。帕金森病（PD）与姿势不稳以及认知控制平衡任务受损有关。然而，尚无研究调查观察姿势失衡是否会影响PD患者的姿势稳定性，以及患者是否能够抑制视觉性姿势干扰。在本研究中，采用了一种动作观察范式来评估PD患者和健康老年人对运动感染的姿势反应。在观察静态刺激（对照条件）以及体操运动员在绳索上平衡的点光源显示（生物刺激）过程中，测量姿势稳定性的变化。我们的结果表明，在观察生物刺激期间，仅PD参与者的摇摆面积以及压力中心的前后和内外位移显著增加，而老年受试者则出现正确的稳定反应。这些结果表明，PD导致控制由运动感染引发的自动模仿倾向的能力下降。这种行为可能是无法抑制自动模仿倾向或任务所需认知负荷的结果。无论哪种情况，抑制自动模仿倾向的能力问题对于PD患者可能至关重要，因为这可能会增加跌倒风险和受伤几率。
