Fuster Joaquín M
UCLA Neuropsychiatric Institute, Los Angeles, California 90095-1759, USA.
Int J Psychophysiol. 2006 May;60(2):125-32. doi: 10.1016/j.ijpsycho.2005.12.015. Epub 2006 Apr 19.
The prevalent concept in modular models is that there are discrete cortical domains dedicated more or less exclusively to such cognitive functions as visual discrimination, language, spatial attention, face recognition, motor programming, memory retrieval, and working memory. Most of these models have failed or languished for lack of conclusive evidence. In their stead, network models are emerging as more suitable and productive alternatives. Network models are predicated on the basic tenet that cognitive representations consist of widely distributed networks of cortical neurons. Cognitive functions, namely perception, attention, memory, language, and intelligence, consist of neural transactions within and between these networks. The present model postulates that memory and knowledge are represented by distributed, interactive, and overlapping networks of neurons in association cortex. Such networks, named cognits, constitute the basic units of memory or knowledge. The association cortex of posterior-post-rolandic-regions contains perceptual cognits: cognitive networks made of neurons associated by information acquired through the senses. Conversely, frontal association cortex contains executive cognits, made of neurons associated by information related to action. In both posterior and frontal cortex, cognits are hierarchically organized. At the bottom of that organization-that is, in parasensory and premotor cortex-cognits are small and relatively simple, representing simple percepts or motor acts. At the top of the organization-in temporo-parietal and prefrontal cortex-cognits are wider and represent complex and abstract information of perceptual or executive character. Posterior and frontal networks are associated by long reciprocal cortico-cortical connections. These connections support the dynamics of the perception-action cycle in sequential behavior, speech, and reasoning.
模块化模型中普遍的概念是，存在一些离散的皮质区域，或多或少专门负责诸如视觉辨别、语言、空间注意力、面部识别、运动编程、记忆检索和工作记忆等认知功能。由于缺乏确凿的证据，这些模型大多已经失败或停滞不前。取而代之的是，网络模型正作为更合适且更具成效的替代方案而出现。网络模型基于这样一个基本信条：认知表征由广泛分布的皮质神经元网络组成。认知功能，即感知、注意力、记忆、语言和智力，由这些网络内部和之间的神经活动组成。当前模型假设，记忆和知识由联合皮质中神经元的分布式、交互式和重叠网络来表征。这样的网络，称为认知体，构成了记忆或知识的基本单元。后罗兰区的联合皮质包含感知认知体：由通过感官获取的信息关联的神经元组成的认知网络。相反，额叶联合皮质包含执行认知体，由与动作相关的信息关联的神经元组成。在后部和额叶皮质中，认知体都是分层组织的。在该组织的底部，即在副感觉区和运动前皮质中，认知体较小且相对简单，代表简单的感知或运动行为。在组织的顶部，即在颞顶叶和前额叶皮质中，认知体更广泛，代表感知或执行性质的复杂抽象信息。后部和额叶网络通过长距离的相互皮质-皮质连接相互关联。这些连接支持连续行为、言语和推理中感知-动作循环的动态过程。
