Cortical intrinsic circuits can support activity propagation through an isofrequency strip of the guinea pig primary auditory cortex
Cortical intrinsic circuits can support activity propagation through an isofrequency strip of the guinea pig primary auditory cortex
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DOI：
10.1093/cercor/bhj018
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发表时间：
2006-05-01
期刊：
影响因子：
3.7
通讯作者：
Nishimura, M
中科院分区：
文献类型：
--
作者：
Song, WJ;Kawaguchi, H;Nishimura, M
纯音引起初级听觉皮层（AI）的一条带（IS）的传播活动。一个基本的问题是丘脑皮质输入和皮质内连接在产生活动中所起的作用。在这里，我们解决了这个问题，在豚鼠体内和体外实时光学成像技术。如前所述，在AI中，音调诱发的活动沿背腹沿着条（IS）传播。我们发现，一个电脉冲内的带，触发活动传播的时空模式高度相似的音调诱发激活。电诱发活动的传播速度明显慢于音调诱发活动的传播速度，但与皮质切片中的侧向活动传播速度相当，表明体内电诱发活动的传播是由皮质内回路介导的。为了验证这一观点，我们用化学方法损毁听觉丘脑;在这些动物中，AI的电诱发活动没有受到影响，尽管音调诱发活动被取消了。此外，在切片的AI，在层II/III的电诱发活动传播的程度显着大于在冠状切片水平切片。总之，我们的研究结果表明，AI中的皮质内连接使局部诱发活动能够在整个IS中传播。
A pure tone evokes propagating activities in a strip of the primary auditory cortex (AI), an isofrequency strip (IS). A fundamental issue concerns the roles that thalamocortical input and intracortical connectivity play in generating the activities. Here we addressed this issue in guinea pigs using in vivo and in vitro real-time optical imaging techniques. As reported previously, tone-evoked activity propagated dorsoventrally along a strip (an IS) in AI. We found that an electrical pulse applied focally within the strip, triggered activity propagation with a spatiotemporal pattern highly similar to tone-evoked activation. The propagation velocity of electrically evoked activity was significantly slower than that of tone-evoked activity, but was comparable to the velocity of lateral activity propagation in cortical slices, suggesting that the electrically evoked activity propagation in vivo is mediated by intracortical circuits. To test this notion, we lesioned the auditory thalamus chemically; in such animals, electrically evoked activity in AI was not affected, although tone-evoked activity was abolished. Further, in slices of the AI, the extent of electrically evoked activity propagation in layer II/III was significantly larger in coronal slices than in horizontal slices. Together, our results suggest that intracortical connectivity in AI enables a focally evoked activity to propagate throughout an IS.