Ethanol is one of the most widely used drugs - with many psychoactive effects, including anxiolysis. The deleterious effects on brain function and general health of chronic and high-level ethanol use are well-studied. However, the neurophysiology of acute low dose ethanol has not been systematically investigated. Here, we examined the effects of low dose (0.25 and 0.5 g/kg) ethanol on midline (prefrontal, cingulate and retrosplenial) neocortical and hippocampal theta oscillations in freely moving rats. We also tested low dose ethanol on reticular-elicited and running-elicited hippocampal theta frequency and assessed the linear relationship of theta frequency to stimulation intensity and running speed, respectively. Low dose ethanol had mixed effects on neocortical theta oscillations. It most reliably reduced theta frequency, produced a weak inverted-U effect on theta power, and had no detectable effect on cortico-hippocampal theta coherence. Ethanol dose-dependently decreased the y-intercept of the speed-theta frequency function without affecting the slope, but decreased the slope of the stimulation intensity-theta frequency function without affecting the y-intercept; thus decreasing theta frequency in both cases. We conclude low dose ethanol has weak but detectable effects on neocortical and hippocampal theta oscillations. These effects may underlie positive cognitive and behavioural outcomes reported in the literature using low dose ethanol. The double dissociation of slope and y-intercept specific changes relating to different methods of hippocampal theta elicitation presents the potential to probe multiple mechanisms contributing to anxiolytic effects on theta and so hippocampal function.

中文翻译：

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低剂量乙醇对皮质和海马θ振荡的混合影响。

乙醇是使用最广泛的药物之一-具有许多精神活性，包括抗焦虑作用。研究了长期和大量使用乙醇对脑功能和总体健康的有害影响。但是，急性低剂量乙醇的神经生理学尚未得到系统的研究。在这里，我们检查了低剂量（0.25和0.5 g / kg）乙醇对自由移动大鼠中线（前额叶，扣带回和脾后）新皮层和海马theta振荡的影响。我们还对网状引起的和跑步引起的海马θ频率测试了低剂量乙醇，并分别评估了θ频率与刺激强度和跑步速度的线性关系。低剂量乙醇对新皮层θ振荡有混合作用。它最可靠地降低了theta频率，产生的倒U型对theta力的影响较弱，而对皮质-海马theta相干性没有可检测的影响。乙醇可剂量依赖性地降低速度-θ频率函数的y截距，而不会影响斜率，但会降低刺激强度-θ频率函数的斜率，而不会影响y截距。因此在两种情况下都降低了θ频率。我们得出结论，低剂量乙醇对新皮层和海马θ振荡具有微弱但可检测的作用。这些影响可能是使用低剂量乙醇在文献中报道的积极认知和行为结果的基础。