Department of Neurobiology and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
J Neurosci. 2012 Aug 29;32(35):12165-79. doi: 10.1523/JNEUROSCI.1181-12.2012.
The neocortex depends upon a relative balance of recurrent excitation and inhibition for its operation. During spontaneous Up states, cortical pyramidal cells receive proportional barrages of excitatory and inhibitory synaptic potentials. Many of these synaptic potentials arise from the activity of nearby neurons, although the identity of these cells is relatively unknown, especially for those underlying the generation of inhibitory synaptic events. To address these fundamental questions, we developed an in vitro submerged slice preparation of the mouse entorhinal cortex that generates robust and regular spontaneous recurrent network activity in the form of the slow oscillation. By performing whole-cell recordings from multiple cell types identified with green fluorescent protein expression and electrophysiological and/or morphological properties, we show that distinct functional subpopulations of neurons exist in the entorhinal cortex, with large variations in contribution to the generation of balanced excitation and inhibition during the slow oscillation. The most active neurons during the slow oscillation are excitatory pyramidal and inhibitory fast spiking interneurons, receiving robust barrages of both excitatory and inhibitory synaptic potentials. Weak action potential activity was observed in stellate excitatory neurons and somatostatin-containing interneurons. In contrast, interneurons containing neuropeptide Y, vasoactive intestinal peptide, or the 5-hydroxytryptamine (serotonin) 3a receptor, were silent. Our data demonstrate remarkable functional specificity in the interactions between different excitatory and inhibitory cortical neuronal subtypes, and suggest that it is the large recurrent interaction between pyramidal neurons and fast spiking interneurons that is responsible for the generation of persistent activity that characterizes the depolarized states of the cortex.
大脑皮层的运作依赖于兴奋和抑制的相对平衡。在自发的 Up 状态期间，皮质锥体神经元会接收兴奋性和抑制性突触电位的比例性爆发。这些突触电位中的许多都源于附近神经元的活动，尽管这些细胞的身份相对未知，特别是对于那些产生抑制性突触事件的细胞。为了解决这些基本问题，我们开发了一种体外淹没切片制备的小鼠内侧前额叶皮层，以慢振荡的形式产生强大而规则的自发的、反复的网络活动。通过对用绿色荧光蛋白表达和电生理及/或形态学特性鉴定的多种细胞类型进行全细胞记录，我们表明内侧前额叶皮层存在不同功能的神经元亚群，它们在慢振荡期间产生平衡的兴奋和抑制方面存在很大的差异。在慢振荡期间最活跃的神经元是兴奋性锥体神经元和抑制性快速放电中间神经元，它们会接收强大的兴奋性和抑制性突触电位爆发。在星状兴奋性神经元和含生长抑素的中间神经元中观察到弱的动作电位活动。相比之下，含有神经肽 Y、血管活性肠肽或 5-羟色胺（血清素）3a 受体的中间神经元是沉默的。我们的数据表明，不同兴奋性和抑制性皮质神经元亚型之间的相互作用具有显著的功能特异性，并表明正是锥体神经元和快速放电中间神经元之间的大的反复相互作用负责产生持续活动，这是皮层去极化状态的特征。
