Department of Psychology, University of Jyväskylä, Jyväskylä, Finland.
Neuroscience. 2010 Feb 17;165(4):1538-45. doi: 10.1016/j.neuroscience.2009.11.044. Epub 2009 Nov 27.
Hippocampal functioning, in the form of theta band oscillation, has been shown to modulate and predict cerebellar learning of which rabbit eyeblink conditioning is perhaps the most well-known example. The contribution of hippocampal neural activity to cerebellar learning is only possible if there is a functional connection between the two structures. Here, in the context of trace eyeblink conditioning, we show (1) that, in addition to the hippocampus, prominent theta oscillation also occurs in the cerebellum, and (2) that cerebellar theta oscillation is synchronized with that in the hippocampus. Further, the degree of phase synchrony (PS) increased both as a response to the conditioning stimuli and as a function of the relative power of hippocampal theta oscillation. However, the degree of PS did not change as a function of either training or learning nor did it predict learning rate as the hippocampal theta ratio did. Nevertheless, theta band synchronization might reflect the formation of transient neural assemblies between the hippocampus and the cerebellum. These findings help us understand how hippocampal function can affect eyeblink conditioning, during which the critical plasticity occurs in the cerebellum. Future studies should examine cerebellar unit activity in relation to hippocampal theta oscillations in order to discover the detailed mechanisms of theta-paced neural activity.
海马体功能以θ波段振荡的形式表现出来，已经被证明可以调节和预测小脑学习，而兔子眨眼条件反射可能是最著名的例子。只有当这两个结构之间存在功能连接时，海马体神经活动对小脑学习的贡献才是可能的。在这里，在痕迹眨眼条件反射的背景下，我们表明：（1）除了海马体外，小脑体中也会出现明显的θ振荡；（2）小脑体的θ振荡与海马体的θ振荡同步。此外，相位同步（PS）的程度随着条件刺激的反应以及海马体θ振荡的相对功率而增加。然而，PS 的程度既不会随着训练或学习而变化，也不会像海马体θ比率那样预测学习速度。尽管如此，θ 频带同步可能反映了海马体和小脑体之间瞬时神经集合的形成。这些发现有助于我们了解海马体功能如何影响眨眼条件反射，因为在眨眼条件反射中，关键的可塑性发生在小脑体中。未来的研究应该检查小脑体单元活动与海马体θ振荡之间的关系，以发现θ 节拍神经活动的详细机制。
