Sliwinska Magdalena W, Khadilkar Manali, Campbell-Ratcliffe Jonathon, Quevenco Frances, Devlin Joseph T
Cognitive, Perceptual and Brain Sciences, University College London London, UK.
Front Psychol. 2012 May 28;3:161. doi: 10.3389/fpsyg.2012.00161. eCollection 2012.
Reading is a difficult task that, at a minimum, requires recognizing a visual stimulus and linking it with its corresponding sound and meaning. Neurologically, this involves an anatomically distributed set of brain regions cooperating to solve the problem. It has been hypothesized that the supramarginal gyrus (SMG) contributes preferentially to phonological aspects of word processing and thus plays an important role in visual word recognition. Here, we used chronometric transcranial magnetic stimulation (TMS) to investigate the functional specificity and timing of SMG involvement in reading visually presented words. Participants performed tasks designed to focus on either the phonological, semantic, or visual aspects of written words while double pulses of TMS (delivered 40 ms apart) were used to temporarily interfere with neural information processing in the left SMG at five different time windows. Stimulation at 80/120, 120/160, and 160/200 ms post-stimulus onset significantly slowed subjects' reaction times in the phonological task. This inhibitory effect was specific to the phonological condition, with no effect of TMS in the semantic or visual tasks, consistent with claims that SMG contributes preferentially to phonological aspects of word processing. The fact that the effect began within 80-120 ms of the onset of the stimulus and continued for approximately 100 ms, indicates that phonological processing initiates early and is sustained over time. These findings are consistent with accounts of visual word recognition that posit parallel activation of orthographic, phonological, and semantic information that interact over time to settle into a distributed, but stable, representation of a word.
阅读是一项艰巨的任务，至少需要识别视觉刺激并将其与相应的声音和意义联系起来。从神经学角度来看，这涉及一组在解剖学上分布的脑区协同工作来解决这个问题。据推测，缘上回（SMG）在单词处理的语音方面发挥着优先作用，因此在视觉单词识别中起着重要作用。在这里，我们使用计时经颅磁刺激（TMS）来研究SMG参与视觉呈现单词阅读的功能特异性和时间。参与者执行旨在关注书面单词的语音、语义或视觉方面的任务，同时使用双脉冲TMS（间隔40毫秒发放）在五个不同的时间窗口暂时干扰左SMG中的神经信息处理。在刺激开始后80/120、120/160和160/200毫秒进行刺激显著减慢了受试者在语音任务中的反应时间。这种抑制作用特定于语音条件，TMS对语义或视觉任务没有影响，这与SMG在单词处理的语音方面优先发挥作用的说法一致。这种效应在刺激开始后80 - 120毫秒内开始并持续约100毫秒，这一事实表明语音处理很早就开始并持续一段时间。这些发现与视觉单词识别的观点一致，即正字法、语音和语义信息同时被激活，并随着时间相互作用，以形成一个分布式但稳定的单词表征。
