Division of Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping 581 83, Sweden
Division of Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping 581 83, Sweden.
eNeuro. 2023 Feb 23;10(2). doi: 10.1523/ENEURO.0349-22.2022. Print 2023 Feb.
Facial expressions are an increasingly used tool to assess emotional experience and affective state during experimental procedures in animal models. Previous studies have successfully related specific facial features with different positive and negative valence situations, most notably in relation to pain. However, characterizing and interpreting such expressions remains a major challenge. We identified seven easily visualizable facial parameters on mouse profiles, accounting for changes in eye, ear, mouth, snout and face orientation. We monitored their relative position on the face across time and throughout sequences of positive and aversive gustatory and somatosensory stimuli in freely moving mice. Facial parameters successfully captured response profiles to each stimulus and reflected spontaneous movements in response to stimulus valence, as well as contextual elements such as habituation. Notably, eye opening was increased by palatable tastants and innocuous touch, while this parameter was reduced by tasting a bitter solution and by painful stimuli. Mouse ear posture appears to convey a large part of emotional information. Facial expressions accurately depicted welfare and affective state in a time-sensitive manner, successfully correlating time-dependent stimulation. This study is the first to delineate rodent facial expression features in multiple positive valence situations, including in relation to affective touch. We suggest using this facial expression assay might provide mechanistic insights into emotional expression and improve the translational value of experimental studies in rodents on pain and other states.
面部表情是一种在动物模型的实验过程中评估情感体验和情感状态的日益常用的工具。先前的研究已经成功地将特定的面部特征与不同的正性和负性效价情境联系起来，这在与疼痛有关的研究中尤为明显。然而，对面部表情进行特征描述和解释仍然是一个主要挑战。我们在老鼠的侧脸上确定了七个易于观察的面部参数，这些参数可以反映眼睛、耳朵、嘴巴、鼻子和面部的方向变化。我们在自由活动的老鼠身上监测它们在正性和负性味觉和躯体感觉刺激序列中随时间的相对位置变化。面部参数成功地捕捉到了对每种刺激的反应特征，并反映了对刺激效价的自发运动，以及习惯化等环境因素。值得注意的是，可口的味觉刺激和无害的触觉会增加眼睛的张开度，而尝到苦味溶液和受到疼痛刺激会减少这个参数。老鼠耳朵的姿势似乎传达了很大一部分情感信息。面部表情能够以时间敏感的方式准确地描绘福利和情感状态，成功地与时间相关的刺激相关联。这项研究首次在多种正性效价情境下描绘了啮齿动物的面部表情特征，包括与情感触摸有关的特征。我们建议使用这种面部表情分析方法可能会为情感表达提供机制上的见解，并提高啮齿动物在疼痛和其他状态下的实验研究的转化价值。
