Sulpizio Valentina, Neri Anna, Fattori Patrizia, Galletti Claudio, Pitzalis Sabrina, Galati Gaspare
Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy; Cognitive and Motor Rehabilitation and Neuroimaging Unit, Santa Lucia Foundation (IRCCS Fondazione Santa Lucia), Rome, Italy.
Brain Imaging Laboratory, Department of Psychology, Sapienza University, Rome, Italy.
Neuroscience. 2020 May 10;434:22-34. doi: 10.1016/j.neuroscience.2020.03.019. Epub 2020 Mar 19.
Object prehension typically includes a transport phase (reaching) and a grip phase (grasping). Within the posterior parietal cortex (PPC), grasping movements have been traditionally associated to a lateral activation, although recent monkey evidence suggests also a medial involvement. Here, we wanted to determine whether grasping-related activities are present in the human dorsomedial parietal cortex, by focusing on two cortical regions specialized in the monkey in controlling limb movements, i.e., V6A (composed by its ventral and dorsal sectors, V6Av and V6Ad, respectively) and PEc, both recently defined also in humans. We acquired functional magnetic resonance images while participants performed both real (pantomimed) and imagined grasping of visually-presented objects. We found that the human areas V6Ad (hV6Ad) and PEc (hPEc) were both activated by real grasping, whereas hV6Ad only was activated by the imagery of grasping movements. hV6Av was not involved in either types of grasping. These results speak against the traditional notion of a medial-to-lateral segregation of reaching versus grasping information within the PPC and strengthen the idea that the human dorsomedial parietal cortex implements the whole complex pattern of visuomotor transformations required for object-oriented actions. Our findings suggest that hV6Ad is particularly involved in implementing all the visuomotor transformations needed to create an abstract representation of the object-directed action, while hPEc is involved in implementing the sensorimotor transformations needed to actually perform that action.
物体抓握通常包括一个运输阶段（伸手）和一个抓握阶段（抓取）。在顶叶后皮质（PPC）内，抓握动作传统上与外侧激活有关，尽管最近猴子实验的证据表明内侧也有参与。在这里，我们想通过关注猴子中专门控制肢体运动的两个皮质区域，即V6A（分别由其腹侧和背侧部分V6Av和V6Ad组成）和PEc（最近在人类中也有定义），来确定人类背内侧顶叶皮质中是否存在与抓握相关的活动。我们在参与者进行真实（模拟）和想象中抓握视觉呈现物体的过程中获取了功能磁共振图像。我们发现，人类的V6Ad区（hV6Ad）和PEc区（hPEc）在真实抓握时均被激活，而只有hV6Ad区在抓握动作的想象过程中被激活。hV6Av区在两种抓握类型中均未参与。这些结果与PPC内伸手与抓握信息从内侧到外侧分离的传统观念相悖，并强化了人类背内侧顶叶皮质执行面向物体动作所需的整个复杂视觉运动转换模式的观点。我们的研究结果表明，hV6Ad区特别参与创建物体导向动作的抽象表征所需的所有视觉运动转换，而hPEc区则参与实际执行该动作所需的感觉运动转换。
