Stem Cell and Brain Research Institute, Institut National de la Sante et de la Recherche Medicale U846, 18 avenue du Doyen Lepine, Bron, France.
Cereb Cortex. 2011 Jun;21(6):1254-72. doi: 10.1093/cercor/bhq201. Epub 2010 Nov 2.
To what extent cortical pathways show significant weight differences and whether these differences are consistent across animals (thereby comprising robust connectivity profiles) is an important and unresolved neuroanatomical issue. Here we report a quantitative retrograde tracer analysis in the cynomolgus macaque monkey of the weight consistency of the afferents of cortical areas across brains via calculation of a weight index (fraction of labeled neurons, FLN). Injection in 8 cortical areas (3 occipital plus 5 in the other lobes) revealed a consistent pattern: small subcortical input (1.3% cumulative FLN), high local intrinsic connectivity (80% FLN), high-input form neighboring areas (15% cumulative FLN), and weak long-range corticocortical connectivity (3% cumulative FLN). Corticocortical FLN values of projections to areas V1, V2, and V4 showed heavy-tailed, lognormal distributions spanning 5 orders of magnitude that were consistent, demonstrating significant connectivity profiles. These results indicate that 1) connection weight heterogeneity plays an important role in determining cortical network specificity, 2) high investment in local projections highlights the importance of local processing, and 3) transmission of information across multiple hierarchy levels mainly involves pathways having low FLN values.
皮质通路的权重差异在何种程度上显著，以及这些差异在动物之间是否一致（从而构成稳健的连接谱），是一个重要且尚未解决的神经解剖学问题。在这里，我们通过计算权重指数（标记神经元的分数，FLN），报告了在食蟹猴中的一项定量逆行示踪分析，以研究跨脑皮质区域传入的权重一致性。在 8 个皮质区域（3 个枕叶加 5 个其他叶）的注射显示出一致的模式：小的皮质下输入（1.3%的累积 FLN），高局部内在连接（80%FLN），来自相邻区域的高输入形式（15%累积 FLN），以及弱的长程皮质间连接（3%累积 FLN）。到 V1、V2 和 V4 区域的皮质间 FLN 值呈长尾、对数正态分布，跨越 5 个数量级，具有一致性，显示出显著的连接谱。这些结果表明：1）连接权重异质性在确定皮质网络特异性方面起着重要作用；2）对局部投射的高投入突出了局部处理的重要性；3）跨多个层次水平传递信息主要涉及具有低 FLN 值的途径。
