Reading words aloud is a fundamental aspect of literacy. The rapid rate at which multiple distributed neural substrates are engaged in this process can only be probed via techniques with high spatiotemporal resolution. We probed this with direct intracranial recordings covering most of the left hemisphere in 46 humans (26 male, 20 female) as they read aloud regular, exception and pseudo-words. We used this to create a spatiotemporal map of word processing and to derive how broadband activity varies with multiple word attributes critical to reading speed: lexicality, word frequency, and orthographic neighborhood. We found that lexicality is encoded earliest in mid-fusiform (mFus) cortex, and precentral sulcus, and is represented reliably enough to allow single-trial lexicality decoding. Word frequency is first represented in mFus and later in the inferior frontal gyrus (IFG) and inferior parietal sulcus (IPS), while orthographic neighborhood sensitivity resides solely in IPS. We thus isolate the neural correlates of the distributed reading network involving mFus, IFG, IPS, precentral sulcus, and motor cortex and provide direct evidence for parallel processes via the lexical route from mFus to IFG, and the sublexical route from IPS and precentral sulcus to anterior IFG.

SIGNIFICANCE STATEMENT Reading aloud depends on multiple complex cerebral computations: mapping from a written letter string on a page to a sequence of spoken sound representations. Here, we used direct intracranial recordings in a large cohort while they read aloud known and novel words, to track, across space and time, the progression of neural representations of behaviorally relevant factors that govern reading speed. We find, concordant with cognitive models of reading, that known and novel words are differentially processed through a lexical route, sensitive to frequency of occurrence of known words in natural language, and a sublexical route, performing letter-by-letter construction of novel words.

大声朗读单词是识字的一个基本方面。多个分布式神经基质参与该过程的快速速率只能通过高时空分辨率的技术来探测。我们通过覆盖 46 名人类（26 名男性，20 名女性）左半球大部分区域的直接颅内录音来探究这一点，因为他们大声朗读常规、异常和伪单词。我们用它来创建文字处理的时空图，并得出宽带活动如何随着对阅读速度至关重要的多个单词属性而变化：词汇、词频和拼写邻域。我们发现词汇性最早在中梭状（mFus）皮层和中央前沟中编码，并且足够可靠地表示以允许单次尝试词汇性解码。词频首先由 mFus 表示，然后由额下回 (IFG) 和顶下沟 (IPS) 表示，而拼写邻域敏感性仅由 IPS 表示。因此，我们分离了涉及 mFus、IFG、IPS、中央前沟和运动皮层的分布式阅读网络的神经相关性，并通过从 mFus 到 IFG 的词汇路径以及从 IPS 和中央前沟到前 IFG。

意义陈述朗读取决于多种复杂的大脑计算：从页面上的书面字母串映射到一系列口头声音表示。在这里，我们在一大群人大声朗读已知和新单词时使用直接颅内录音，以跨越空间和时间跟踪控制阅读速度的行为相关因素的神经表征的进展。我们发现，与阅读的认知模型一致，已知单词和新单词通过对自然语言中已知单词出现频率敏感的词汇路径和对新单词进行逐字母构建的潜词汇路径进行差异化处理。