Jones E G
Department of Anatomy and Neurobiology, University of California, Irvine 92717-1275, USA.
Adv Neurol. 1998;77:49-71; discussion 72-3.
Past theories about the circuitry that promotes integration of the whole cerebral cortex and thalamus during forebrain activities that underlie different states of consciousness have relied on the intralaminar nuclei as the sources of diffuse thalamocortical projections that could facilitate spread of activity across many cortical areas. Evidence is presented to show the presence of a matrix of superficially projecting cells extending throughout the whole thalamus that could form a substrate for diffusion of activity across the cortex. The superficially projecting cells in monkeys are distinguished by immunoreactivity for the calcium-binding protein calbindin. They are found in all thalamic nuclei and are increased in some nuclei. They not only project to superficial layers of the cortex but do so over wide areas, unconstrained by boundaries between areas. They are innervated by subcortical inputs that lack the topographic order and physiological precision of the principal sensory pathways. Superimposed on the matrix, but only in certain nuclei, is a core of cells characterized by immunoreactivity for another calcium-binding protein, parvalbumin. These project to middle layers of the cortex in an area-specific and topographically ordered manner. They are innervated by subcortical inputs that are typically precise in having a high degree of topographic order and readily identifiable physiological properties. The parvalbumin cells provide the sensory and other inputs to the cortex that are to be used as a basis for perception. The diffusely projecting calbindin cells can form a basis for the engagement of multiple cortical areas and thalamic nuclei, especially when recruited by corticothalamic connections. Diffusion of activity across multiple areas and thalamic nuclei is essential for the binding of all aspects of sensory experience into a single framework of consciousness.
过去有关在前脑活动期间促进整个大脑皮层和丘脑整合的神经回路的理论，这些活动是不同意识状态的基础，该理论依赖于板内核作为弥散性丘脑皮质投射的来源，这种投射可促进活动在许多皮质区域的传播。有证据表明，存在一种贯穿整个丘脑的表面投射细胞基质，它可以形成活动在整个皮层扩散的基础。猴子中的表面投射细胞以对钙结合蛋白钙结合蛋白的免疫反应性为特征。它们存在于所有丘脑核中，并且在一些核中数量增加。它们不仅投射到皮层的表层，而且投射范围广泛，不受区域边界的限制。它们由缺乏主要感觉通路的拓扑顺序和生理精度的皮质下输入支配。叠加在该基质上，但仅在某些核中，是一个细胞核心，其特征是对另一种钙结合蛋白小白蛋白具有免疫反应性。这些细胞以区域特异性和拓扑有序的方式投射到皮层的中层。它们由通常具有高度拓扑顺序且生理特性易于识别的精确皮质下输入支配。小白蛋白细胞为皮层提供感觉和其他输入，这些输入将用作感知的基础。弥散性投射的钙结合蛋白细胞可以形成多个皮质区域和丘脑核参与的基础，特别是当被皮质丘脑连接募集时。活动在多个区域和丘脑核之间的扩散对于将感觉体验的所有方面整合到一个单一的意识框架中至关重要。
