Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, Campus de San Juan, Avenida Ramón y Cajal s/n, 03550, San Juan de Alicante, Spain.
Brain Struct Funct. 2018 Apr;223(3):1051-1069. doi: 10.1007/s00429-017-1529-5. Epub 2017 Oct 28.
The axons forming the corpus callosum sustain the interhemispheric communication across homotopic cortical areas. We have studied how neurons throughout the columnar extension of the retrosplenial cortex integrate the contralateral input from callosal projecting neurons in cortical slices. Our results show that pyramidal neurons in layers 2/3 and the large, thick-tufted pyramidal neurons in layer 5B showed larger excitatory callosal responses than layer 5A and layer 5B thin-tufted pyramidal neurons, while layer 6 remained silent to this input. Feed-forward inhibitory currents generated by fast spiking, parvalbumin expressing interneurons recruited by callosal axons mimicked the response size distribution of excitatory responses across pyramidal subtypes, being larger in those of superficial layers and in the layer 5B thick-tufted pyramidal cells. Overall, the combination of the excitatory and inhibitory currents evoked by callosal input had a strong and opposed effect in different layers of the cortex; while layer 2/3 pyramidal neurons were powerfully inhibited, the thick-tufted but not thin-tufted pyramidal neurons in layer 5 were strongly recruited. We believe that these results will help to understand the functional role of callosal connections in physiology and disease.
胼胝体形成的轴突维持着大脑半球间同源皮质区的信息交流。我们研究了在大脑回后部延伸的柱状结构中，神经元如何整合来自投射到皮质的胼胝体神经元的对侧输入。我们的结果表明，与 5A 层和 5B 层薄刺突锥体细胞相比，2/3 层的锥体细胞和 5B 层厚刺突锥体细胞表现出更大的兴奋性胼胝体反应，而 6 层对这种输入保持沉默。由快速放电的、表达 Parvalbumin 的中间神经元产生的前馈抑制电流，由胼胝体轴突募集，模拟了兴奋性反应在不同锥体细胞亚型之间的反应大小分布，在浅层和 5B 层厚刺突锥体细胞中更大。总的来说，由胼胝体输入引起的兴奋性和抑制性电流的组合在皮质的不同层中具有强烈的相反作用；虽然 2/3 层的锥体细胞受到强烈抑制，但 5 层的厚刺突但不是薄刺突锥体细胞被强烈募集。我们相信这些结果将有助于理解胼胝体连接在生理和疾病中的功能作用。
