NEURAL ORGANIZATION OF COGNITION

现代认知神经科学的核心原则之一是，认知的神经结构被组织成解剖学上分离的子系统（模块），执行不同的功能。 假设潜在的神经隔离是遗传预先确定的，通常是合理的，但有些情况下，这种假设并不容易适应。此外，神经科学中越来越多的证据表明，经验可以而且确实导致大脑组织中所谓的定量变化（例如，现有功能区域的大小变化）。 因此，我们很自然地会问：经验是否会导致大脑模块化组织的质的变化（例如，以前没有定位的功能的神经隔离），或者神经模块是否总是由遗传学硬连接的？ 先前的患者工作证明了经验依赖性功能的选择性损伤（例如，阅读和写）表明，经验可能确实能够产生神经隔离，尽管对这些发现的解释可能存在争议。 我们建议通过使用一种独立的方法（神经影像学）来补充病变研究，从而开发与该问题相关的会聚证据。 在这个问题上取得进展可能对我们理解神经组织、解释神经系统患者以及最终对脑损伤患者的康复具有重要意义。我们建议使用的方法是功能磁共振成像（fMRI）。 功能磁共振成像有许多特点，使其成为解决经验依赖性神经隔离问题的理想方法：（1）其空间分辨率（1- 5 mm 3）足够精细以检测功能模块的解剖分离，（2）通常可以在个体中获得显著结果，使得不需要跨受试者进行平均（这是一个关键点，因为所研究的潜在神经组织可能在个体之间不同），以及（3）它可以用于神经学上完整的人类受试者。我们的计划是通过调查三个子问题来发展关于经验依赖性神经分离的汇聚证据：（1）字母识别是否与数字识别分离？(2)关于数字的语义知识与关于其他类别的语义知识是分离的吗？(3)不同的语言在双语者中是否被隔离？ 我们选择这些域有四个原因。 首先，在每种情况下，推定的分离功能都可能因脑损伤而选择性受损（这表明它可能是分离的）。 其次，在每种情况下，假设任何潜在的神经隔离都是硬连线的，这是有问题的。 第三，功能可以与控制任务相对较好地匹配（使得将积极结果归因于伪影变得更加困难）。 第四，功能可以很容易地使用功能磁共振成像（例如，它们不需要大范围的运动）。 通过平行研究这三个领域，我们希望开发收敛的证据，使我们能够得出更普遍的结论相关的经验依赖性神经隔离的问题。

One of the central tenets of modern cognitive neuroscience is that the neural architecture of cognition is organized into anatomically segregated subsystems (modules) that perform different functions. It is usually plausible to assume that the underlying neural segregation was genetically predetermined, but there are cases that this hypothesis cannot easily accommodate. Furthermore, a growing body of evidence in neuroscience has demonstrated that experience can and does lead to what might be called quantitative changes in brain organization (e.g., changes in the size of an existing functional region). It is therefore natural to ask: Can experience lead to qualitative changes in the brain's modular organization (such as the neural segregation of a function that was not previously localized) or are neural modules always hard-wired by genetics? Previous patient work demonstrating selective impairments in experience-dependent functions (e.g., reading and writing) suggests that experience may indeed be able to produce neural segregation, although the interpretation of those findings can be controversial. We propose to develop converging evidence relevant to the issue by using an independent methodology (neuroimaging) that complements lesion studies. Making progress on this issue could have important implications for our understanding of neural organization, for the interpretation of neurological patients, and ultimately for the rehabilitation of patients with brain damage. The method we propose to use is functional magnetic resonance imaging (fMRI). fMRI has a number of features that make it ideal for addressing the issue of experience-dependent neural segregation: (1) its spatial resolution (1-5mm3) is sufficiently fine to detect anatomic segregation of functional modules, (2) significant results can typically be obtained in individuals making it unnecessary to average across subjects (a critical point because the underlying neural organization under study may differ across individuals), and (3) it can be used with human subjects who are neurologically intact. Our plan is to develop converging evidence regarding experience- dependent neural segregation by investigating three sub- questions: (1) Is letter recognition segregated from digit recognition? (2) Is semantic knowledge about numbers segregated from semantic knowledge about other categories? (3) Are different languages segregated in bilinguals? We chose these domains for four reasons. First, in each case the putatively segregated function can be selectively impaired by brain damage (suggesting that it may be segregated). Second, in each case it is problematic to assume that any underlying neural segregation could be hard-wired. Third, the functions can be relatively well matched with control tasks (making it more difficult to attribute positive results to artifacts). And fourth, the functions can be readily studied using fMRI (e.g., they do not require extensive movement). By studying these three domains in parallel we hope to develop converging evidence that will allow us to draw more general conclusions relevant to the issue of experience-dependent neural segregation.