Garcea Frank E, Mahon Bradford Z
Department of Brain and Cognitive Sciences, University of Rochester, USA; Center for Visual Science, University of Rochester, USA.
Department of Brain and Cognitive Sciences, University of Rochester, USA; Center for Visual Science, University of Rochester, USA; Department of Neurosurgery, University of Rochester, USA.
Neuropsychologia. 2014 Jul;60:131-43. doi: 10.1016/j.neuropsychologia.2014.05.018. Epub 2014 Jun 2.
Manipulating a tool according to its function requires the integration of visual, conceptual, and motor information, a process subserved in part by left parietal cortex. How these different types of information are integrated and how their integration is reflected in neural responses in the parietal lobule remains an open question. Here, participants viewed images of tools and animals during functional magnetic resonance imaging (fMRI). k-Means clustering over time series data was used to parcellate left parietal cortex into subregions based on functional connectivity to a whole brain network of regions involved in tool processing. One cluster, in the inferior parietal cortex, expressed privileged functional connectivity to the left ventral premotor cortex. A second cluster, in the vicinity of the anterior intraparietal sulcus, expressed privileged functional connectivity with the left medial fusiform gyrus. A third cluster in the superior parietal lobe expressed privileged functional connectivity with dorsal occipital cortex. Control analyses using Monte Carlo style permutation tests demonstrated that the clustering solutions were outside the range of what would be observed based on chance 'lumpiness' in random data, or mere anatomical proximity. Finally, hierarchical clustering analyses were used to formally relate the resulting parcellation scheme of left parietal tool representations to previous work that has parcellated the left parietal lobule on purely anatomical grounds. These findings demonstrate significant heterogeneity in the functional organization of manipulable object representations in left parietal cortex, and outline a framework that generates novel predictions about the causes of some forms of upper limb apraxia.
根据工具的功能来操作工具需要整合视觉、概念和运动信息，这一过程部分由左顶叶皮层负责。这些不同类型的信息是如何整合的，以及它们的整合如何在顶叶小叶的神经反应中体现，仍然是一个悬而未决的问题。在这里，参与者在功能磁共振成像（fMRI）期间观看工具和动物的图像。基于与参与工具处理的全脑区域网络的功能连接，使用k均值聚类对时间序列数据进行分析，将左顶叶皮层划分为不同的子区域。一个位于顶下小叶的聚类与左腹侧运动前皮层表现出特殊的功能连接。第二个位于顶内沟前部附近的聚类与左内侧梭状回表现出特殊的功能连接。第三个位于顶上叶的聚类与枕叶背侧皮层表现出特殊的功能连接。使用蒙特卡洛风格置换检验的对照分析表明，聚类结果超出了基于随机数据中的偶然“聚集性”或仅仅基于解剖学邻近性所观察到的范围。最后，使用层次聚类分析将左顶叶工具表征的最终分割方案与之前基于纯粹解剖学基础对左顶叶小叶进行分割的研究正式联系起来。这些发现表明左顶叶皮层中可操作物体表征的功能组织存在显著的异质性，并勾勒出一个框架，该框架对某些形式的上肢失用症的病因产生了新的预测。
