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上分离的子系统(模块)，这些子系统执行不同的功能。通常，假设潜在的神经隔离是遗传上预先决定的，这通常是合理的，但有一些情况下，这种假设不容易适应。此外，神经科学中越来越多的证据表明，经验可以而且确实会导致所谓的大脑组织的量化变化(例如，现有功能区的大小变化)。因此，人们很自然地会问：经验是否会导致大脑模块组织发生质的变化(例如，神经分离了一种以前并未定位的功能)，或者神经模块总是由遗传决定的？先前的病人研究表明，经验依赖的功能(例如，阅读和写作)存在选择性损伤，这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(神经成像)来发展与这一问题相关的聚合证据，以补充病变研究。在这一问题上取得进展可能对我们理解神经组织、解释神经学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)。功能磁共振成像具有许多功能，使其成为解决经验依赖型神经隔离问题的理想选择：(1)其空间分辨率(1-5mm3)足够精细，足以检测功能模块的解剖隔离；(2)在个体身上通常可以获得显著的结果，因此没有必要对不同的受试者进行平均(这是一个临界点，因为所研究的潜在神经组织可能因个体而异)，以及(3)它可以用于神经学完好的人类受试者。我们的计划是通过调查三个子问题来发展关于经验依赖型神经分离的聚合证据：(1)字母识别和数字识别是分开的吗？(2)关于数字的语义知识和关于其他类别的语义知识是分开的吗？(3)双语者中不同的语言是否分开？我们选择这些领域有四个原因。首先，在每一种情况下，假定分离的功能都可能因脑损伤而选择性地受损(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可能是硬连线的，这都是有问题的。第三，这些功能可以相对较好地与控制任务相匹配(这使得将积极的结果归因于构件更加困难)。第四，使用功能磁共振成像可以很容易地研究这些功能(例如，它们不需要广泛的运动)。通过对这三个领域的并行研究，我们希望发展出趋同的证据，使我们能够得出与经验相关的神经分离问题的更一般的结论。

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.