Department of Sensory and Cognitive Physiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
Neurosci Res. 2010 Oct;68(2):107-13. doi: 10.1016/j.neures.2010.06.009. Epub 2010 Jun 23.
In the primary auditory cortex (AI), a pure tone evokes propagating activity along a strip of the cortex. We have previously shown that focal activation of AI triggers autonomously propagating activity that resembles tone-evoked activity (Song et al., 2006). Because a focal spontaneous activity is expected to trigger similar activity propagation, spontaneous activity resembling tone-evoked activity may exist in AI. Here we tested this possibility by optical imaging of AI in guinea pigs. After obtaining tone-evoked activities, we made long-duration optical recordings (9-40s) and isolated spontaneous activities from respiration and heartbeat noises using independent component analyses. Spontaneous activities were found all over AI, in all animals examined. Of all spontaneous events, 33.6% showed significant correlation in spatio-temporal pattern with tone-evoked activities. Simulation using a model that captures the temporal feature of spontaneous response in single channels but sets no constraint among channels, generated no spontaneous events that resembled tone-evoked activations. These results show the existence of spontaneous events similar in spatio-temporal pattern to tone-evoked activations in AI. Such spontaneous events are likely a manifestation of cortical structures that govern the pattern of distributed activation in AI.
在初级听觉皮层（AI）中，纯音会引发沿着皮层的一条带传播的活动。我们之前已经表明，AI 的焦点激活会引发类似于音调诱发活动的自主传播活动（Song 等人，2006）。由于预期焦点自发活动会引发类似的活动传播，因此 AI 中可能存在类似于音调诱发活动的自发活动。在这里，我们通过豚鼠的 AI 光学成像来测试这种可能性。在获得音调诱发活动后，我们进行了长时间的光学记录（9-40 秒），并使用独立成分分析从呼吸和心跳噪声中分离自发活动。在所有检查的动物中，自发活动遍布整个 AI。在所有自发事件中，有 33.6%在时空模式上与音调诱发活动有显著相关性。使用一种模型进行模拟，该模型可以捕获单个通道中自发反应的时间特征，但不限制通道之间的关系，没有产生类似于音调诱发激活的自发事件。这些结果表明，在 AI 中存在与音调诱发活动在时空模式上相似的自发事件。这种自发事件可能是控制 AI 中分布式激活模式的皮质结构的表现。
