Monaco Simona, Chen Ying, Medendorp W P, Crawford J D, Fiehler Katja, Henriques Denise Y P
York University, Centre for Vision Research, Toronto, ON, Canada.
Cereb Cortex. 2014 Jun;24(6):1540-54. doi: 10.1093/cercor/bht006. Epub 2013 Jan 29.
Grasping behaviors require the selection of grasp-relevant object dimensions, independent of overall object size. Previous neuroimaging studies found that the intraparietal cortex processes object size, but it is unknown whether the graspable dimension (i.e., grasp axis between selected points on the object) or the overall size of objects triggers activation in that region. We used functional magnetic resonance imaging adaptation to investigate human brain areas involved in processing the grasp-relevant dimension of real 3-dimensional objects in grasping and viewing tasks. Trials consisted of 2 sequential stimuli in which the object's grasp-relevant dimension, its global size, or both were novel or repeated. We found that calcarine and extrastriate visual areas adapted to object size regardless of the grasp-relevant dimension during viewing tasks. In contrast, the superior parietal occipital cortex (SPOC) and lateral occipital complex of the left hemisphere adapted to the grasp-relevant dimension regardless of object size and task. Finally, the dorsal premotor cortex adapted to the grasp-relevant dimension in grasping, but not in viewing, tasks, suggesting that motor processing was complete at this stage. Taken together, our results provide a complete cortical circuit for progressive transformation of general object properties into grasp-related responses.
抓握行为需要选择与抓握相关的物体维度，而与物体的整体大小无关。先前的神经影像学研究发现，顶内沟皮层处理物体大小，但尚不清楚可抓握维度（即物体上选定两点之间的抓握轴）或物体的整体大小是否会触发该区域的激活。我们使用功能磁共振成像适应性来研究在抓握和观察任务中处理真实三维物体的抓握相关维度所涉及的人脑区域。试验由两个连续的刺激组成，其中物体的抓握相关维度、其整体大小或两者都是新颖的或重复的。我们发现，在观察任务期间，距状沟和纹外视觉区域适应物体大小，而与抓握相关维度无关。相比之下，上顶枕叶皮层（SPOC）和左半球的枕外侧复合体适应抓握相关维度，而与物体大小和任务无关。最后，背侧运动前皮层在抓握任务中适应抓握相关维度，但在观察任务中不适应，这表明在这个阶段运动处理已经完成。综上所述，我们的结果提供了一个完整的皮质回路，用于将一般物体属性逐步转化为与抓握相关的反应。
