Enhanced dendritic activity in awake rats
Enhanced dendritic activity in awake rats
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DOI：
10.1073/pnas.0910379106
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发表时间：
2009-12-01
影响因子：
11.1
通讯作者：
Larkum, Matthew E.
中科院分区：
文献类型：
--
作者：
Murayama, Masanori;Larkum, Matthew E.
人们对清醒动物的树突活动几乎一无所知，对其与行为的关系就更不了解了。第5层（L5）锥体神经元的丛状树突位于第1层，从次级丘脑核和高级皮质区来的远端轴突到达这里。这类输入非常依赖于活跃的丘脑皮质回路和大脑高级区域的活动，因此很可能受到动物意识状态的严重影响。如果锥体神经元的树突积极参与这一过程，那么在清醒状态下树突的活动应该会大大增加。在这里，我们使用“潜望镜”光纤系统测量L5锥体神经元树突中的钙活性。对清醒大鼠和麻醉大鼠的后肢进行感觉刺激后，对其感觉运动皮层进行记录。后肢刺激引起的双相树突反应高度依赖于脑状态。在清醒状态下，有一个明显的缓慢、延迟的反应，其积分平均比麻醉状态大14倍。此外，树突活动的急剧增加与随后后肢运动的强度密切相关。这些变化局限于L5锥体树突，并没有反映在2/3层（L2/3）神经元对空气刺激的反应中（实际上在清醒状态下会减少）。结果表明，L5锥体树突的活动是清醒行为的神经关联。
Almost nothing is known about dendritic activity in awake animals and even less about its relationship to behavior. The tuft dendrites of layer 5 (L5) pyramidal neurons lie in layer 1, where long-range axons from secondary thalamic nuclei and higher cortical areas arrive. This class of input is very dependent on active thalamocortical loops and activity in higher brain areas and so is likely to be heavily influenced by the conscious state of the animal. If, as has been suggested, the dendrites of pyramidal neurons actively participate in this process, dendritic activity should greatly increase in the awake state. Here, we measured calcium activity in L5 pyramidal neuron dendrites using the "periscope" fiberoptic system. Recordings were made in the sensorimotor cortex of awake and anesthetized rats following sensory stimulation of the hind-limb. Bi-phasic dendritic responses evoked by hindlimb stimulation were extremely dependent on brain state. In the awake state, there was a prominent slow, delayed response whose integral was on average 14-fold larger than in the anesthetized state. Moreover, the dramatic increases in dendritic activity closely correlated to the strength of subsequent hindlimb movement. These changes were confined to L5 pyramidal dendrites and were not reflected in the response of layer 2/3 (L2/3) neurons to air-puff stimuli in general (which actually decreased in the awake state). The results demonstrate that the activity of L5 pyramidal dendrites is a neural correlate of awake behavior.