Nokia Miriam S, Penttonen Markku, Korhonen Tapani, Wikgren Jan
Department of Psychology, P.O. Box 35 (MaC), FIN-40014 University of Jyväskylä, Finland.
Neurobiol Learn Mem. 2008 Jul;90(1):62-70. doi: 10.1016/j.nlm.2008.01.005. Epub 2008 Feb 21.
In 1978, Berry and Thompson showed that the amount of theta (3-8Hz) activity in the spontaneous hippocampal EEG predicted learning rate in subsequent eyeblink conditioning in rabbits. More recently, the absence of theta activity during the training trial has been shown to have a detrimental effect on learning rate. Here, we aimed to further explore the relationship between theta activity and classical eyeblink conditioning by determining how the relative power of hippocampal theta activity [theta/(theta+delta) ratio] changes during both unpaired control and paired training phases. We found that animals with a higher hippocampal theta ratio immediately before conditioning learned faster and also that in these animals the theta ratio was higher throughout both experimental phases. In fact, while the hippocampal theta ratio remained stable in the fast learners as a function of training, it decreased in the slow learners already during unpaired training. In addition, the presence of hippocampal theta activity enhanced the hippocampal model of the conditioned response (CR) and seemed to be beneficial for CR performance in terms of peak latency during conditioning, but did not have any effect when the animals showed asymptotic learning. Together with earlier findings, these results imply that the behavioral state in which hippocampal theta activity is absent is detrimental for learning, and that the behavioral state in which hippocampal theta activity dominates is beneficial for learning, at least before a well-learned state is achieved.
1978年，贝里和汤普森表明，兔自发海马脑电图中θ波（3 - 8赫兹）活动的量可预测随后眨眼条件反射中的学习速率。最近，已表明训练试验期间缺乏θ波活动会对学习速率产生不利影响。在此，我们旨在通过确定海马θ波活动的相对功率[θ/（θ + δ）比率]在非配对对照和配对训练阶段如何变化，进一步探索θ波活动与经典眨眼条件反射之间的关系。我们发现，在条件反射前海马θ波比率较高的动物学习更快，并且在这些动物中，整个两个实验阶段的θ波比率都较高。事实上，虽然快速学习者的海马θ波比率作为训练的函数保持稳定，但在缓慢学习者中，它在非配对训练期间就已经下降。此外，海马θ波活动的存在增强了条件反应（CR）的海马模型，并且在条件反射期间的峰值潜伏期方面似乎对CR表现有益，但当动物表现出渐近学习时则没有任何影响。与早期发现一起，这些结果表明缺乏海马θ波活动的行为状态对学习有害，而海马θ波活动占主导的行为状态对学习有益，至少在达到良好学习状态之前是这样。
