Center for Neural Circuits and Behavior, Department of Neuroscience, School of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
Neuron. 2011 Oct 6;72(1):41-8. doi: 10.1016/j.neuron.2011.08.015.
In primary sensory cortices, there are two main sources of excitation: afferent sensory input relayed from the periphery and recurrent intracortical input. Untangling the functional roles of these two excitatory pathways is fundamental for understanding how cortical neurons process sensory stimuli. Odor representations in the primary olfactory (piriform) cortex depend on excitatory sensory afferents from the olfactory bulb. However, piriform cortex pyramidal cells also receive dense intracortical excitatory connections, and the relative contribution of these two pathways to odor responses is unclear. Using a combination of in vivo whole-cell voltage-clamp recording and selective synaptic silencing, we show that the recruitment of intracortical input, rather than olfactory bulb input, largely determines the strength of odor-evoked excitatory synaptic transmission in rat piriform cortical neurons. Furthermore, we find that intracortical synapses dominate odor-evoked excitatory transmission in broadly tuned neurons, whereas bulbar synapses dominate excitatory synaptic responses in more narrowly tuned neurons.
在初级感觉皮层中，有两个主要的兴奋源：来自外周的传入感觉输入和皮层内的回传兴奋输入。理清这两种兴奋性通路的功能作用对于理解皮层神经元如何处理感觉刺激至关重要。初级嗅觉（梨状）皮层中的气味表示依赖于嗅球的兴奋性感觉传入。然而，梨状皮层锥体神经元也接收密集的皮层内兴奋性连接，这两种途径对气味反应的相对贡献尚不清楚。通过结合体内全细胞膜片钳记录和选择性突触沉默，我们表明，皮层内输入的募集，而不是嗅球输入，在很大程度上决定了大鼠梨状皮层神经元中气味诱发的兴奋性突触传递的强度。此外，我们发现，在广泛调谐的神经元中，皮层内突触主导气味诱发的兴奋性传递，而在更窄调谐的神经元中，嗅球突触主导兴奋性突触反应。
