Excitatory local connections of superficial neurons in rat auditory cortex.
Excitatory local connections of superficial neurons in rat auditory cortex.
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DOI：
10.1523/jneurosci.2093-08.2008
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发表时间：
2008-10-29
期刊：
影响因子：
--
通讯作者：
Callaway EM
中科院分区：
文献类型：
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作者：
Barbour DL;Callaway EM
哺乳动物的大脑皮层由多个区域组成，专门处理许多不同感觉模式的信息。虽然每个皮质区域的基本结构是相似的，但专门的神经连接可能调节独特的信息处理需求。相对于初级视觉（V1）和体感（S1）皮层，我们对初级听觉皮层（A1）的内在连通性知之甚少。为了更好地了解从丘脑到大鼠A1的信息流，我们利用激光诱导谷氨酸释放的快速、高通量筛选方法构建了单个神经元的兴奋性输入图。我们发现2/3层锥体神经元的兴奋性输入与V1和S1相似；这些细胞主要从第2-4层受到强烈的激发。然而，解剖和生理观察表明，A1的第4层兴奋性神经元的输入和输出与V1和S1的不同。A1的第2/3层锥体在第4层有大量的轴突，光刺激表明这些锥体可以连接到第4层兴奋性神经元。此外，大部分或所有这些第4层兴奋性神经元都投射出局部皮层回路。与S1和V1不同，第4层的反馈完全由间接的局部电路介导，包括2/3层向深层的投射和对第4层的深度反馈，A1的第4层将丘脑和强烈的第4层反复兴奋输入与来自第2/3层的相对直接反馈结合起来，并提供直接的皮层输出。
The mammalian cerebral cortex consists of multiple areas specialized for processing information for many different sensory modalities. Although the basic structure is similar for each cortical area, specialized neural connections likely mediate unique information processing requirements. Relative to primary visual (V1) and somatosensory (S1) cortices, little is known about the intrinsic connectivity of primary auditory cortex (A1). To better understand the flow of information from the thalamus to and through rat A1, we made use of a rapid, high-throughput screening method exploiting laser-induced uncaging of glutamate to construct excitatory input maps of individual neurons. We found that excitatory inputs to layer 2/3 pyramidal neurons were similar to those in V1 and S1; these cells received strong excitation primarily from layers 2–4. Both anatomical and physiological observations, however, indicate that inputs and outputs of layer 4 excitatory neurons in A1 contrast with those in V1 and S1. Layer 2/3 pyramids in A1 have substantial axonal arbors in layer 4, and photostimulation demonstrates that these pyramids can connect to layer 4 excitatory neurons. Furthermore, most or all of these layer 4 excitatory neurons project out of the local cortical circuit. Unlike S1 and V1, where feedback to layer 4 is mediated exclusively by indirect local circuits involving layer 2/3 projections to deep layers and deep feedback to layer 4, layer 4 of A1 integrates thalamic and strong layer 4 recurrent excitatory input with relatively direct feedback from layer 2/3 and provides direct cortical output.