Ballermann M, Tompkins G, Whishaw I Q
Department of Psychology and Neuroscience, University of Lethbridge, and NeuroDetective Inc., 4401, University Drive, Lethbridge, Canada.
Behav Brain Res. 2000 Apr;109(1):49-57. doi: 10.1016/s0166-4328(99)00164-3.
Rats are capable of reaching for food with a single forelimb, but since they locate the target of their reach using olfaction, it is unclear how they adjust their limb movement to compensate for errors. Although it is thought that their reaching movement is ballistic and can only be adjusted by trial and error, whether they can use haptic cues to aid in locating and identifying a target has not been examined. The present study addressed this question by allowing rats to reach through a slot for rigidly held pieces of uncooked pasta of varying thickness, which could be oriented vertically or horizontally from different points around the slot and which were attached to a force transducer. The tasks required that animals not only adjust their reach and grasp to the target's location but also identify the target based on its texture. Acquisition curves were made of head orientation, limb transport trajectories, number of attempts per success, paw orientation, breaking direction and force of the grasp. A haptic discrimination test used pasta and similar sized metal rods with different tactile properties as discriminanda. The results indicated that whereas postural orientation and limb transport trajectory were not modified as a function of target orientation, paw orientation and grasp force did vary as a function of the sensory qualities of the target object, and the rats could make a haptic discriminative choice of a target object. The results show that the rat is capable of adjusting paw movements using haptic information, suggesting that somatosensory features of sensorimotor control of limb and paw movements in carnivores and primates are shared by rodents. This commonality points to a conservation of motor control in mammals, explains some of the idiosyncratic features of rat reaching behavior, and confirms that rodents provide a good model for investigating sensorimotor functions.
大鼠能够用单个前肢够取食物，但由于它们利用嗅觉来定位够取目标，所以尚不清楚它们如何调整肢体运动以补偿误差。尽管人们认为它们的够取动作是一次性的，只能通过试错来调整，但它们是否能利用触觉线索来辅助定位和识别目标尚未得到研究。本研究通过让大鼠通过一个狭槽去够取固定着的不同厚度的生意大利面条片来解决这个问题，这些面条片可以从狭槽周围的不同点垂直或水平放置，并连接到一个力传感器上。这些任务要求动物不仅要根据目标位置调整其够取和抓握动作，还要根据目标的质地识别目标。获取了头部朝向、肢体移动轨迹、每次成功尝试的次数、爪子朝向、折断方向和抓握力的曲线。一个触觉辨别测试使用了意大利面条和具有不同触觉特性的类似尺寸的金属棒作为辨别物。结果表明，虽然姿势朝向和肢体移动轨迹不会随着目标方向而改变，但爪子朝向和抓握力确实会随着目标物体的感官特性而变化，并且大鼠能够对目标物体进行触觉辨别选择。结果表明，大鼠能够利用触觉信息调整爪子的运动，这表明食肉动物和灵长类动物肢体和爪子运动的感觉运动控制中的体感特征在啮齿动物中也存在。这种共性表明哺乳动物的运动控制具有保守性，解释了大鼠够取行为的一些特殊特征，并证实啮齿动物为研究感觉运动功能提供了一个良好的模型。
