Institute of Cognitive Neuroscience, Department of Neuropsychology, Ruhr University Bochum, Bochum, Germany.
Cortex. 2013 Apr;49(4):1110-25. doi: 10.1016/j.cortex.2012.03.023. Epub 2012 Apr 16.
Sensory/functional accounts of semantic memory organization emphasize that object representations in the brain reflect the modalities involved in object knowledge acquisition. The present study aimed to elucidate the impact of different types of object-related sensorimotor experience on the neural representations of novel objects. Sixteen subjects engaged in an object matching task while their brain activity was assessed with functional magnetic resonance imaging (fMRI), before and after they acquired knowledge about previously unfamiliar objects. In three training sessions subjects learned about object function, actively manipulating only one set of objects (manipulation training objects, MTO), and visually exploring a second set (visual training objects, VTO). A third object set served as control condition and was not part of the training (no training objects, NTO). While training-related activation increases were observed in the fronto-parietal cortex for both VTO and MTO, post training activity in the left inferior/middle frontal gyrus and the left posterior inferior parietal lobule was higher for MTO than VTO and NTO. As revealed by Dynamic Causal Modeling of effective connectivity between the regions with enhanced post training activity, these effects were likely caused, respectively, by a down-regulation of a fronto-parietal tool use network in response to VTO, and by an increased connectivity for MTO. This pattern of findings indicates that the modalities involved in sensorimotor experience influence the formation of neural representations of objects in semantic memory, with manipulation experience specifically yielding higher activity in regions of the fronto-parietal cortex.
感觉/功能论的语义记忆组织强调，大脑中的物体表征反映了获取物体知识所涉及的模态。本研究旨在阐明不同类型的与物体相关的感觉运动经验对新物体的神经表征的影响。16 名被试在进行物体匹配任务时，其大脑活动通过功能磁共振成像（fMRI）进行评估，在他们获得了以前不熟悉的物体的知识之前和之后。在三个训练课程中，被试学习了物体的功能，仅主动操作一组物体（操作训练物体，MTO），并视觉探索第二组物体（视觉训练物体，VTO）。第三组物体作为对照条件，不参与训练（无训练物体，NTO）。虽然 VTO 和 MTO 都在前额顶叶皮层观察到与训练相关的激活增加，但 MTO 比 VTO 和 NTO 在左额中/下部和左后下部顶叶回的训练后活动更高。通过对增强的后训练活动的区域之间的有效连通性进行动态因果建模，揭示出这些效应可能分别是由于 VTO 导致的前顶叶工具使用网络的下调，以及 MTO 的连通性增加引起的。这一发现模式表明，感觉运动经验所涉及的模态影响语义记忆中物体的神经表征的形成，而操作经验特别导致额顶叶皮层区域的更高活动。
