Centre for Cognitive Ageing and Cognitive Epidemiology (CCACE), Department of Psychology, University of Edinburgh, UK; Neuroscience and Aphasia Research Unit (NARU), Division of Neuroscience & Experimental Psychology, School of Biological Sciences, University of Manchester, UK.
Neuroscience and Aphasia Research Unit (NARU), Division of Neuroscience & Experimental Psychology, School of Biological Sciences, University of Manchester, UK.
Cortex. 2018 Apr;101:107-118. doi: 10.1016/j.cortex.2018.01.015. Epub 2018 Feb 2.
The left and right ventral anterior temporal lobes (vATL) have been implicated as key regions for the representation of conceptual knowledge. However, the nature and degree of hemispheric specialisation in their function is unclear. To address this issue, we investigated hemispheric specialisation in the ventral temporal lobes using a distortion-corrected spin-echo fMRI protocol that enhanced signal in vATL. We employed an orthogonal manipulation of stimulus (written words vs pictured objects) and task (naming vs recognition). Words elicited left-lateralised vATL activation while objects elicited bilateral activation with no hemispheric bias. In contrast, posterior ventral temporal cortex exhibited a rightward bias for objects as well as a leftward bias for words. Naming tasks produced left-lateralised activation in vATL while activity for recognition was equal in left and right vATLs. These findings are incompatible with proposals that left and right ATLs are strongly modular in function, since these predict rightward as well as leftward biases. Instead, they support an alternative model in which (a) left and right ATL together form a bilateral, integrated system for the representation of concepts and (b) within this system, graded hemispheric specialisation emerges as a consequence of differential connectivity with other neural systems. On this view, greater left vATL activation for written word processing develops as a consequence of the inputs this region receives from left-lateralised visual word processing system in posterior temporal cortex. Greater left vATL activation during naming tasks is most likely due to connectivity with left-lateralised speech output systems in prefrontal and motor cortices.
左、右腹侧前颞叶（vATL）被认为是概念知识表现的关键区域。然而，它们在功能上的半球专门化的性质和程度尚不清楚。为了解决这个问题，我们使用了一种经过失真校正的自旋回波 fMRI 协议来研究腹侧颞叶的半球专门化，该协议增强了 vATL 中的信号。我们采用了刺激（书面单词与图片物体）和任务（命名与识别）的正交操作。单词引发了左侧 vATL 的激活，而物体则引发了双侧激活，没有半球偏向。相比之下，后部腹侧颞叶皮层对物体表现出右偏，对单词则表现出左偏。命名任务在 vATL 中产生了左侧激活，而识别活动在左、右 vATL 中是相等的。这些发现与左、右 ATL 在功能上具有强烈模块性的观点不一致，因为这些观点预测了右偏和左偏。相反，它们支持了一种替代模型，即（a）左、右 ATL 共同形成了一个双侧、整合的系统，用于概念的表示，（b）在这个系统中，随着与其他神经系统的连接差异，出现了分级的半球专门化。在这种观点下，左 vATL 在处理书面单词时的更大激活是由于该区域从后部颞叶中的左侧视觉单词处理系统接收的输入而发展起来的。命名任务中左 vATL 激活增加的原因很可能是与左外侧化的言语输出系统在前额叶和运动皮层中的连接。
