Department of Neuroscience, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
Neuron. 2011 Oct 6;72(1):49-56. doi: 10.1016/j.neuron.2011.08.020.
In the piriform cortex, individual odorants activate a unique ensemble of neurons that are distributed without discernable spatial order. Piriform neurons receive convergent excitatory inputs from random collections of olfactory bulb glomeruli. Pyramidal cells also make extensive recurrent connections with other excitatory and inhibitory neurons. We introduced channelrhodopsin into the piriform cortex to characterize these intrinsic circuits and to examine their contribution to activity driven by afferent bulbar inputs. We demonstrated that individual pyramidal cells are sparsely interconnected by thousands of excitatory synaptic connections that extend, largely undiminished, across the piriform cortex, forming a large excitatory network that can dominate the bulbar input. Pyramidal cells also activate inhibitory interneurons that mediate strong, local feedback inhibition that scales with excitation. This recurrent network can enhance or suppress bulbar input, depending on whether the input arrives before or after the cortex is activated. This circuitry may shape the ensembles of piriform cells that encode odorant identity.
在梨状皮层中，个体气味激活了分布没有明显空间顺序的独特神经元集合。梨状神经元从嗅球小球的随机集合中接收会聚的兴奋性输入。 锥体细胞也与其他兴奋性和抑制性神经元进行广泛的复发性连接。 我们将通道视紫红质引入梨状皮层，以描述这些内在电路，并研究它们对由传入球茎输入驱动的活动的贡献。 我们证明，单个锥体细胞通过数千个兴奋性突触连接稀疏地相互连接，这些连接在很大程度上不受阻碍地延伸穿过梨状皮层，形成一个可以支配球茎输入的大型兴奋性网络。 锥体细胞还激活中间神经元，介导与兴奋成正比的强烈局部反馈抑制。 这种复发性网络可以增强或抑制球茎输入，具体取决于输入是在皮层被激活之前还是之后到达。 这种电路可能会形成编码气味身份的梨状细胞集合。
