Self-organized synaptic plasticity contributes to the shaping of γ and β oscillations in vitro
Self-organized synaptic plasticity contributes to the shaping of γ and β oscillations in vitro
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DOI：
10.1523/jneurosci.21-22-09053.2001
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发表时间：
2001-11-15
影响因子：
5.3
通讯作者：
Traub, RD
中科院分区：
文献类型：
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作者：
Bibbig, A;Faulkner, HJ;Traub, RD
γ（30-70 Hz）振荡，随后是β（10-30 Hz）振荡，在人类中由感官刺激诱发，并且可能涉及工作记忆。在海马切片中，通过强的双位点强直刺激可以诱发现象学上类似的γ-> β振荡。较弱的刺激仅导致双部位同步伽马。体外振荡具有类似记忆的特征：（1）EPSP在γ-> β期间增加;（2）在强的单部位刺激后，双部位刺激产生去激活的γ;（3）单个同步的γ-> β时期允许随后的弱刺激诱导同步的γ-> β。特征2和3持续>50分钟，因此不太可能由突触前效应引起。先前的模型复制了γ-> β转变，假设K+电导增加，锥体EPSC中存在特别增加。在这里，我们已经改进了模型，因此锥体->锥体和锥体->中间神经元突触都是可修改的。该模型以自组织的方式复制了伽马-β过渡，沿着上述特征1和2。如果学习率或K+电流块的时间过程与刺激强度分级，则特征3被复制。突触可塑性允许模拟振荡在由轴突传导延迟超过10毫秒分开的站点之间同步。我们的数据表明，伽马振荡的一个功能是允许突触可塑性，然后以β振荡的形式表达。我们提出，伽马振荡的周期，类似于25毫秒，是“设计”，以匹配的时间过程中的[Ca 2 +]（i）在树突的波动，从而促进学习。
gamma (30-70 Hz) followed by beta (10-30 Hz) oscillations are evoked in humans by sensory stimuli and may be involved in working memory. Phenomenologically similar gamma-->beta oscillations can be evoked in hippocampal slices by strong two-site tetanic stimulation. Weaker stimulation leads only to two-site synchronized gamma. In vitro oscillations have memory-like features: (1) EPSPs increase during gamma-->beta; (2) after a strong one-site stimulus, two-site stimulation produces desynchronized gamma; and (3) a single synchronized gamma-->beta epoch allows a subsequent weak stimulus to induce synchronized gamma-->beta. Features 2 and 3 last >50 min and so are unlikely to be caused by presynaptic effects. A previous model replicated the gamma-->beta transition when it was assumed that K+ conductance(s) increases and there is an ad hoc increase in pyramidal EPSCs. Here, we have refined the model, so that both pyramidal-->pyramidal and pyramidal-->interneuron synapses are modifiable. This model, in a self-organized way, replicates the gamma-->beta transition, along with features 1 and 2 above. Feature 3 is replicated if learning rates, or the time course of K+ current block, are graded with stimulus intensity. Synaptic plasticity allows simulated oscillations to synchronize between sites separated by axon conduction delays over 10 msec. Our data suggest that one function of gamma oscillations is to permit synaptic plasticity, which is then expressed in the form of beta oscillations. We propose that the period of gamma oscillations, similar to 25 msec, is "designed" to match the time course of [Ca2+](i) fluctuations in dendrites, thus facilitating learning.