Deschênes M, Veinante P, Zhang Z W
Centre de Recherche Université Laval-Robert Giffard, Hôpital Robert Giffard, 2601 de la Canardière, Beauport, Québec, Canada.
Brain Res Brain Res Rev. 1998 Dec;28(3):286-308. doi: 10.1016/s0165-0173(98)00017-4.
All neocortical areas receive inputs from and project back to the thalamus. It is often said that the corticothalamic projections are organized in a way that reciprocates the spatial distribution of thalamocortical pathways. The present review examines to what extent this rule of reciprocity is actually supported by the most recent neuroanatomical data, particularly those relating to the central organization of the vibrissal sensory system in the rat. A critical survey of previous studies is made and new results are presented concerning the fine-grained organization of corticothalamic projections in this sensory system. Together, prior results and the present set of new data confirm the existence of both, reciprocal and nonreciprocal patterns of corticothalamic connectivity. This conclusion leads us to propose that the spatial organization of corticothalamic connections complies with a more fundamental rule, the rule of parity, from which reciprocity follows as a general, but not obligatory consequence. The rule of parity states that the distribution of corticothalamic projections across and within the thalamic nuclei is determined by the branching patterns of the different classes of prethalamic afferents. The anatomical, developmental and physiological consequences of this rule are discussed. The rule of parity suggests that, according to the behavioral context, both prethalamic and corticothalamic pathways may function in a feedback mode.
所有新皮质区域都接收来自丘脑的输入并向丘脑投射回去。人们常说，皮质丘脑投射的组织方式与丘脑皮质通路的空间分布相互对应。本综述探讨了这种对应规则在多大程度上得到了最新神经解剖学数据的实际支持，特别是那些与大鼠触须感觉系统的中枢组织有关的数据。对先前的研究进行了批判性审视，并给出了关于该感觉系统中皮质丘脑投射的精细组织的新结果。先前的结果和当前的这组新数据共同证实了皮质丘脑连接中存在相互和非相互模式。这一结论使我们提出，皮质丘脑连接的空间组织符合一个更基本的规则，即奇偶性规则，相互对应是该规则的一个普遍但非必然的结果。奇偶性规则指出，皮质丘脑投射在丘脑核团之间和内部的分布是由不同类别的丘脑前传入纤维的分支模式决定的。讨论了该规则的解剖学、发育学和生理学后果。奇偶性规则表明，根据行为背景，丘脑前和皮质丘脑通路都可能以反馈模式发挥作用。
