Center for Behavioral Neuroscience, Georgia State University, Atlanta, GA, United States; Department of Psychology, Georgia State University, Atlanta, GA, United States; Neuroscience Institute, Georgia State University, Atlanta, GA, United States.
Center for Behavioral Neuroscience, Georgia State University, Atlanta, GA, United States; Department of Psychology, Georgia State University, Atlanta, GA, United States.
Neuropsychologia. 2011 Apr;49(5):1052-1066. doi: 10.1016/j.neuropsychologia.2011.02.013. Epub 2011 Feb 16.
Glucose enhances memory in a variety of species. In humans, glucose administration enhances episodic memory encoding, although little is known regarding the neural mechanisms underlying these effects. Here we examined whether elevating blood glucose would enhance functional MRI (fMRI) activation and connectivity in brain regions associated with episodic memory encoding and whether these effects would differ depending on the emotional valence of the material. We used a double-blind, within-participants, crossover design in which either glucose (50g) or a saccharin placebo were administered before scanning, on days approximately 1 week apart. We scanned healthy young male participants with fMRI as they viewed emotionally arousing negative pictures and emotionally neutral pictures, intermixed with baseline fixation. Free recall was tested at 5 min after scanning and again after 1 day. Glucose administration increased activation in brain regions associated with successful episodic memory encoding. Glucose also enhanced activation in regions whose activity was correlated with subsequent successful recall, including the hippocampus, prefrontal cortex, and other regions, and these effects differed for negative vs. neutral stimuli. Finally, glucose substantially increased functional connectivity between the hippocampus and amygdala and a network of regions previously implicated in successful episodic memory encoding. These findings fit with evidence from nonhuman animals indicating glucose modulates memory by selectively enhancing neural activity in brain regions engaged during memory tasks. Our results highlight the modulatory effects of glucose and the importance of examining both regional changes in activity and functional connectivity to fully characterize the effects of glucose on brain function and memory.
葡萄糖可增强多种物种的记忆。在人类中，给予葡萄糖可增强情景记忆的编码，尽管对于这些影响的神经机制知之甚少。在这里，我们研究了升高血糖是否会增强与情景记忆编码相关的脑区的功能磁共振成像 (fMRI) 激活和连接，以及这些效应是否会因材料的情绪效价而异。我们使用双盲、内参与者、交叉设计，在大约相隔 1 周的 2 天内，分别在扫描前给予葡萄糖（50g）或蔗糖安慰剂。我们使用 fMRI 扫描健康年轻男性参与者，让他们观看情绪激动的负面图片和情绪中性的图片，同时混合基线固定。在扫描后 5 分钟和 1 天后进行自由回忆测试。葡萄糖给药增加了与成功情景记忆编码相关的大脑区域的激活。葡萄糖还增强了与随后成功回忆相关的区域的激活，包括海马体、前额叶皮层和其他区域，这些效应在负面和中性刺激之间有所不同。最后，葡萄糖大大增加了海马体和杏仁核之间以及先前与成功情景记忆编码相关的一系列区域之间的功能连接。这些发现与来自非人类动物的证据相符，表明葡萄糖通过选择性增强记忆任务中参与的大脑区域的神经活动来调节记忆。我们的结果强调了葡萄糖的调节作用，以及检查区域活动和功能连接的变化以充分描述葡萄糖对大脑功能和记忆的影响的重要性。
