Department of Neuroscience, Canadian Centre for Behavioural Neuroscience, University of Lethbridge, 4401 University Drive, Lethbridge, AB, T1K 3M4, Canada.
Exp Brain Res. 2012 Nov;223(1):121-36. doi: 10.1007/s00221-012-3246-x. Epub 2012 Sep 5.
The reach-to-eat movement is a natural act in which an object or food item is grasped and brought to the mouth. It is one of the earliest forelimb behaviours displayed by human infants, who bring almost all grasped objects to the mouth, and is used daily by adults. In adults, there is a tight coupling between visual attention and the advance phase of the reach-to-eat movement. The target is visually engaged just as hand advance is initiated and visually disengaged just as the target is grasped. This coupling of vision and hand advance suggests that advance is mediated by visual attention and withdrawal by somatosensation. The present study examined when the tight coupling between visual attention and the advance phase of the movement develops in infancy. In a longitudinal study, eight infants, aged 6-12 months, and 20 adults reached for familiar inanimate objects and food items. Visual gaze, hand movement and hand accuracy were measured using frame-by-frame video scoring and 2D kinematic analysis. The study found that the youngest infants (6-8 months) visually engaged the target well before initiating a reaching movement and continued to fixate on the target after it was grasped and as it was brought to the mouth. Between 10 and 12 months of age, infants began to visually engage the target just as the reaching movement was initiated and visually disengaged the target as it was grasped, as did the adults. Over the same developmental time period, the infants developed rotatory hand shaping movements, precision grasping, and improved targeting accuracy both for grasping the object and placing it into the mouth. The results suggest that visual guidance of advance and somatosensory guidance of withdrawal develop together and in concert with hand movement ability and skill.
进食动作是一种自然行为，即物体或食物被抓取并送到口中。这是人类婴儿最早表现出的前肢行为之一，他们几乎会将所有抓取到的物体送到口中，而成人每天也会用到这个动作。在成年人中，视觉注意力和进食前肢动作的前进阶段之间存在紧密的耦合关系。目标在手部开始前进时被视觉锁定，而在目标被抓取时被视觉解除锁定。这种视觉和手部前进的耦合关系表明，前进是由视觉注意力介导的，而撤回则是由躯体感觉介导的。本研究探讨了在婴儿期，视觉注意力和前肢动作的前进阶段之间的紧密耦合关系是何时发展起来的。在一项纵向研究中，8 名 6-12 个月大的婴儿和 20 名成年人伸手去抓熟悉的无生命物体和食物。使用逐帧视频评分和 2D 运动学分析来测量视觉注视、手部运动和手部准确性。研究发现，最年轻的婴儿（6-8 个月）在开始伸手动作之前就很好地注视着目标，并且在目标被抓取后和被送到口中后仍然继续注视着目标。在 10 到 12 个月大时，婴儿开始在伸手动作开始时视觉锁定目标，并在目标被抓取时视觉解除锁定，这与成年人的情况相同。在同一发展时期，婴儿发展出了旋转手部塑造动作、精确抓握，并提高了抓取物体和将物体放入口中的目标准确性。研究结果表明，前进的视觉引导和撤回的躯体感觉引导是一起发展的，并且与手部运动能力和技能一起协调发展。
