Staiger J F, Kötter R, Zilles K, Luhmann H J
C. & O. Vogt-Institute for Brain Research, Heinrich-Heine University Düsseldorf, Germany.
Anat Embryol (Berl). 1999 Apr;199(4):357-65. doi: 10.1007/s004290050234.
A promising way to elucidate neuronal information processing is to establish detailed structure-function relationships of identified single neurons or populations of nerve cells, especially their synaptic connectivity. This has been greatly improved by the development of acute brain slice preparations. The cellular physiology of the rodent primary somatosensory (barrel) cortex has been extensively studied. However, for a meaningful interpretation of physiological experiments the degree and pattern of connectivity has to be known for the particular preparation. Since such studies are not available for rat (P15-25) barrel cortex in vitro, we have traced the cortico-cortical and thalamo-cortical connections in 400-microm-thick slices with biocytin. In coronal slices, a wealth of axonal connections in retrograde and anterograde directions were heavily labeled, resembling the full pattern of cortico-cortical projections described in vivo. The most striking connections were vertical and horizontal connections within the primary somatosensory cortex, as well as a columnar projection to the secondary somatosensory cortex and beyond (mainly the parietal ventral area). Electron microscopic extensions of the study indicated that the full possible set of synaptic contacts with an adult-like appearance was already established in these connections. In thalamo-cortical slices, strong reciprocal connections with the ventrobasal (and to a much lesser extent also the posterior) thalamic nucleus were always observed, together with an intensive ramification of fibers in the reticular nucleus. A striatal terminal field was also consistently found. We conclude that all major intracortical and thalamo-cortical connection are richly preserved in the in vitro slice preparations of rats. Thus, these preparations are suitable for elucidation of the functional interaction of the most crucial brain structures involved in somatosensory information processing combining an in vivo-like anatomical structure with the controlled environment of an in vitro slice.
阐明神经元信息处理的一种有前景的方法是建立已识别的单个神经元或神经细胞群体的详细结构-功能关系，尤其是它们的突触连接性。急性脑片制备技术的发展极大地推动了这一进程。啮齿动物初级躯体感觉（桶状）皮层的细胞生理学已得到广泛研究。然而，为了对生理学实验进行有意义的解释，必须了解特定制备物的连接程度和模式。由于尚无针对大鼠（P15 - 25）体外桶状皮层的此类研究，我们使用生物素追踪了400微米厚切片中的皮质-皮质和丘脑-皮质连接。在冠状切片中，大量逆行和顺行方向的轴突连接被大量标记，类似于体内描述的完整皮质-皮质投射模式。最显著的连接是初级躯体感觉皮层内的垂直和水平连接，以及向次级躯体感觉皮层及以外区域（主要是顶叶腹侧区）的柱状投射。该研究的电子显微镜扩展表明，在这些连接中已经建立了全套具有类似成年外观的突触接触。在丘脑-皮质切片中，总是观察到与腹侧基底（以及在较小程度上还有后部）丘脑核的强相互连接，以及网状核中纤维的密集分支。还始终发现了一个纹状体终末场。我们得出结论，大鼠体外切片制备物中保留了所有主要的皮质内和丘脑-皮质连接。因此，这些制备物适合于阐明参与躯体感觉信息处理的最关键脑结构的功能相互作用，它将类似体内的解剖结构与体外切片的可控环境结合在一起。
