Scientific Institute IRCCS "Eugenio Medea", Polo FVG, Pasian di Prato (UD), Italy.
Scientific Institute IRCCS "Eugenio Medea", Polo FVG, Pasian di Prato (UD), Italy.
Neuroimage Clin. 2024;43:103651. doi: 10.1016/j.nicl.2024.103651. Epub 2024 Aug 8.
Fatigue, defined as a subjective lack of physical and/or mental energy, is a clinical symptom highly characterizing multiple sclerosis (MS). The present study utilized a novel approach to the study of fatigue, examining first person-mental imagery of the symptom. Eighteen right-handed patients with MS (14F, 4 M, mean age 45.8 ± 8.15 years) were evaluated and were compared to nineteen healthy controls (10F, 9 M, mean age 43.15 ± 8.34 years) Patients were all in relapsing remitting form and no patient had presented relapses in the 6 months prior to inclusion in the study. We evaluated their behavioral performance and fMRI activations. We used an fMRI paradigm used to trigger first person-mental imagery of fatigue, through short sentences describing the principal manifestations of fatigue. Participants were asked to imagine the corresponding sensations (Sensory Imagery, SI). As a control, they had to imagine the visual scenes (Visual Imagery, VI) described in short phrases. They made a vividness rating by pressing the corresponding button. Behaviorally, we found that patients' mean scores at the Multidimensional Fatigue Symptom Inventory for the general scale, physical scale, and mental scale were significantly higher than healthy controls (p = 0.05, p = 0.002, p = 0.006 respectively), but not for the emotional scale and for vigor scale (p = 0.207, n.s., p = 0.06, n.s.). In the imagery fMRI task, patients were significantly slower (mean reaction times and standard deviation: 2.24 s ± 0.33) than controls (mean reaction times and standard deviation: 1.918 s ± 0.455) for the SI task (Z=-2.058, p = 0.040), while no significant difference was found for the VI task. Regarding brain mapping, our main result is a group by task interaction. The SI task (vs. VI task) in healthy controls (relative to patients) increased activation in the left inferior parietal lobule. These preliminary results indicate that fatigue is related to dysfunctions in higher-order aspects of motor control, given the role of the posterior parietal lobe in motor planning and multisensory integration.
疲劳是一种主观的身体和/或精神能量缺乏，是多发性硬化症（MS）的一种临床症状。本研究采用了一种新的方法来研究疲劳，首先检查了对该症状的第一人称心理意象。评估了 18 名右利手 MS 患者（14 名女性，4 名男性，平均年龄 45.8 ± 8.15 岁），并与 19 名健康对照组（10 名女性，9 名男性，平均年龄 43.15 ± 8.34 岁）进行了比较。所有患者均为复发缓解型，且在纳入研究前 6 个月内均未发生复发。我们评估了他们的行为表现和 fMRI 激活。我们使用了一种 fMRI 范式来通过描述疲劳主要表现的短句来触发疲劳的第一人称心理意象。要求参与者想象相应的感觉（感觉意象，SI）。作为对照，他们必须想象短短语中描述的视觉场景（视觉意象，VI）。他们通过按下相应的按钮进行生动性评分。行为上，我们发现患者在多维疲劳症状清单的一般量表、身体量表和心理量表上的平均得分明显高于健康对照组（p=0.05，p=0.002，p=0.006），但在情绪量表和活力量表上没有差异（p=0.207，n.s.，p=0.06，n.s.）。在想象 fMRI 任务中，患者的反应时间明显较慢（平均反应时间和标准差：2.24 s ± 0.33）比对照组（平均反应时间和标准差：1.918 s ± 0.455）在 SI 任务中（Z=-2.058，p=0.040），而在 VI 任务中没有发现显著差异。关于大脑映射，我们的主要结果是一个组与任务的相互作用。与 VI 任务相比，健康对照组的 SI 任务（相对于患者）增加了左顶下小叶的激活。这些初步结果表明，鉴于顶后叶在运动规划和多感觉整合中的作用，疲劳与运动控制的高级方面的功能障碍有关。
