Neuroscience and Aphasia Research Unit, School of Psychological Sciences, University of Manchester, UK.
Neuropsychologia. 2010 Apr;48(5):1336-42. doi: 10.1016/j.neuropsychologia.2009.12.036. Epub 2009 Dec 28.
The key question of how the brain codes the meaning of words and pictures is the focus of vigorous debate. Is there a "semantic hub" in the temporal poles where these different inputs converge to form amodal conceptual representations? Alternatively, are there distinct neural circuits that underpin our comprehension of pictures and words? Understanding words might be primarily left-lateralised, linked to other language areas, while semantic representation of pictures may be more bilateral. To elucidate this debate, we used offline, low-frequency, repetitive transcranial magnetic stimulation (rTMS) to disrupt neural processing temporarily in the left or right temporal poles. During the induced refractory period, participants made judgements of semantic association for verbal and pictorial stimuli. The efficiency of semantic processing was reduced by rTMS, yet a perceptual task of comparable difficulty was unaffected. rTMS applied to the left or right temporal poles disrupted semantic processing for words and pictures to the same degree, while rTMS delivered at a control site had no impact. The results confirm that both temporal poles form a critical substrate within the neural network that supports conceptual knowledge, regardless of modality.
大脑如何对单词和图片的含义进行编码是一个激烈争论的焦点问题。在颞极是否存在一个“语义中枢”，不同的输入在此汇聚，形成非模态的概念表示？或者，是否存在不同的神经回路来支持我们对图片和文字的理解？理解文字可能主要是左半球偏向的，与其他语言区域相关联，而图片的语义表示可能更为双边化。为了阐明这一争论，我们使用离线、低频、重复经颅磁刺激(rTMS)暂时干扰左或右颞极的神经处理。在诱导的不应期内，参与者对言语和图片刺激进行语义联想判断。rTMS 降低了语义处理的效率，但难度相当的知觉任务不受影响。rTMS 施加于左或右颞极，对单词和图片的语义处理的干扰程度相同，而施加于对照部位的 rTMS 则没有影响。研究结果证实，颞极两侧都构成了支持概念知识的神经网络的关键基质，而与模态无关。
