Laboratory of Neural Microcircuitry, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne (EPFL), Switzerland.
J Physiol. 2009 Nov 15;587(Pt 22):5411-25. doi: 10.1113/jphysiol.2009.176552. Epub 2009 Sep 21.
The general structure of the mammalian neocortex is remarkably similar across different cortical areas. Despite certain cytoarchitectural specializations and deviations from the general blueprint, the principal organization of the neocortex is relatively uniform. It is not known, however, to what extent stereotypic synaptic pathways resemble each other between cortical areas, and how far they might reflect possible functional uniformity or specialization. Here, we show that frequency-dependent disynaptic inhibition (FDDI) is a generic circuit motif that is present in all neocortical areas we investigated (primary somatosensory, auditory and motor cortex, secondary visual cortex and medial prefrontal cortex of the developing rat). We did find, however, area-specific differences in occurrence and kinetics of FDDI and the short-term dynamics of monosynaptic connections between pyramidal cells (PCs). Connectivity between PCs, both monosynaptic and via FDDI, is higher in primary cortices. The long-term effectiveness of FDDI is likely to be limited by an activity-dependent attenuation of the PC-interneuron synaptic transmission. Our results suggest that the basic construction of neocortical synaptic pathways follows principles that are independent of modality or hierarchical order within the neocortex.
哺乳动物新皮层的总体结构在不同的皮层区域非常相似。尽管存在某些细胞结构的专门化和偏离一般蓝图的情况,但新皮层的主要组织相对统一。然而,尚不清楚在皮层区域之间,刻板的突触通路在多大程度上彼此相似,以及它们在多大程度上反映了可能的功能统一性或专门化。在这里,我们表明,频率依赖性双突触抑制(FDDI)是一种通用的电路模式,存在于我们研究的所有新皮层区域(初级体感、听觉和运动皮层、次级视觉皮层和发育中大鼠的内侧前额叶皮层)中。然而,我们确实发现 FDDI 的出现和动力学以及锥体神经元(PC)之间的单突触连接的短期动力学存在区域特异性差异。PC 之间的连接,无论是单突触还是通过 FDDI,在初级皮层中更高。FDDI 的长期有效性可能受到 PC-中间神经元突触传递的活动依赖性衰减的限制。我们的结果表明,新皮层突触通路的基本构建遵循独立于新皮层内模态或层次顺序的原则。