Whishaw Ian Q, Karl Jenni M
Canadian Centre of Behavioural Neuroscience, Department of Neuroscience.
Can J Exp Psychol. 2014 Dec;68(4):223-35. doi: 10.1037/cep0000042.
Skilled hand use is a striking feature of human behaviour, but in contrast to the view that it recently evolved in the primate lineage, the present paper argues that skilled hand movements have an early phylogenetic origin dating back to the synergies displayed by the pectoral fins of bony fishes. Insights into the function and evolution of hand use stem from the dual visuomotor channel theory, which proposes that prehension is a composite of 2 movements, the reach and the grasp. The reach is in part an egocentric act directed toward the extrinsic (location) features of objects while the grasp is in part an allocentric act directed toward the intrinsic (shape and size) features of objects. Phylogenetic, developmental, and behavioural evidence suggest that the reach and the grasp evolved separately under somatosensory control and were subsequently coordinated with visual control in the primate lineage. Accordingly, parallel pathways from visual cortex came to influence separate reach and grasp systems in parietofrontal cortex, and new descending pathways to the spinal cord came to assist in visually guided reaching. Neural processes related to the "where" of the reach and the "what" of the grasp have had a formative role in shaping cognition more generally.
熟练的手部运用是人类行为的一个显著特征，但与认为它是在灵长类谱系中近期才进化出来的观点不同，本文认为熟练的手部动作在系统发育上有一个早期起源，可以追溯到硬骨鱼胸鳍所展现的协同动作。对手部运用功能和进化的见解源于双视觉运动通道理论，该理论提出抓握是两种动作的组合，即伸手和抓握。伸手部分是一种以自我为中心的行为，指向物体的外在（位置）特征，而抓握部分是一种以他者为中心的行为，指向物体的内在（形状和大小）特征。系统发育、发育和行为方面的证据表明，伸手和抓握在体感控制下分别进化，随后在灵长类谱系中与视觉控制协调起来。因此，来自视觉皮层的平行通路开始影响顶叶额叶皮层中独立的伸手和抓握系统，新的下行通路到达脊髓，协助视觉引导的伸手动作。与伸手的“何处”和抓握的“何物”相关的神经过程在更广泛地塑造认知方面发挥了重要作用。
