Department of Neuroscience, Canadian Centre of Behavioural Neuroscience, University of Lethbridge, Canada.
Department of Neuroscience, Canadian Centre of Behavioural Neuroscience, University of Lethbridge, Canada.
Behav Brain Res. 2020 Mar 2;381:112241. doi: 10.1016/j.bbr.2019.112241. Epub 2019 Oct 23.
There is debate over whether single-handed eating movements, reaching for food and withdrawing the hand to place the food in the mouth, originated in the primate lineage or whether they originated in phylogenetically-earlier Euarchontoglires. Most spontaneous hand use in eating by the laboratory mouse (Mus domestica) involves both hands, and a central question is the extent to which the movements are symmetric. Here we describe an asymmetry of spontaneous single hand use by the head-fixed mouse in making the yo-yo hand movement of removing and replacing a piece of pasta (spaghetti) in the mouth for eating. We also describe the problem/solution of placing into the mouth the end of a held item that protrudes at some distance from the hand. Pasta-eating proceeds in bouts, and a bout starts with raising the hands, which are holding a piece of pasta, to place one end of the pasta in the mouth for biting. A bout ends with lowering the hands, still holding the pasta stem, while the pasta morsel that has been bitten off is chewed. Hand-lowering after the pasta is removed from the mouth is slow, concurrent and symmetric, both when the pasta is held by both hands and when it is held in one hand. Hand-raising to place the pasta in the mouth is fast, consecutive and asymmetric, both when the pasta is held in both hands and when it is held in one hand. Frame-by-frame analyses of the video record combined with kinematic analyses show that a preferred single hand not only directs one end of the pasta to the mouth but also readjusts the trajectory of the pasta if it misses the mouth. The specialized use of a single hand by the mouse, even when the hands are bilaterally engaged, and the corrective asymmetric movements with which one hand adjusts the pasta's trajectory with the other hand playing a supporting role, is discussed in relation to the idea that hand preference, specialization, and dexterity have somatosensory and preprimate origins.
对于单手进食动作，即伸手取食并将手缩回将食物放入口中，是起源于灵长类动物还是起源于更早的真兽亚纲动物，存在争议。实验室小鼠（Mus domestica）进食时最自发的双手使用，涉及双手，一个核心问题是这些动作的对称性程度。在这里，我们描述了一种固定在头部的老鼠在进行将面条（意大利面条）从嘴中取出并放回嘴中进行进食的溜溜球手部运动时，单手使用的不对称性。我们还描述了将伸出手的一定距离的持物的末端放入嘴中的问题/解决方案。进食过程以进食回合进行，回合开始时抬起双手，双手拿着一块面条，将面条的一端放入口中进行咀嚼。回合结束时，双手降低，仍然拿着面条的茎干，同时咬下的面条碎块被咀嚼。将面条从嘴中取出后，手的降低速度较慢，且双手和单手时，手的降低速度较慢且对称。将面条放入嘴中的手的抬起速度较快，双手和单手时，手的抬起速度较快且不对称。结合运动学分析对视频记录进行逐帧分析表明，首选的单手不仅将面条的一端指向嘴，而且如果错过嘴，还会重新调整面条的轨迹。老鼠单手的特殊使用，即使双手同时使用，以及单手使用不对称的纠正动作来调整另一只手的面条轨迹，另一只手发挥支撑作用，这与手的偏好、专业化和灵巧性具有躯体感觉和原猴起源的观点有关。
