Nestor Liam, Roberts Gloria, Garavan Hugh, Hester Robert
Department of Psychology and Institute of Neuroscience, Trinity College, University of Dublin, Ireland.
Neuroimage. 2008 Apr 15;40(3):1328-39. doi: 10.1016/j.neuroimage.2007.12.059. Epub 2008 Jan 12.
The consumption of cannabis has been linked to impairments in human learning and memory, as well as aspects of executive functioning. Cannabis-related impairments in learning and memory in chronic cannabis users, it has been argued, are caused by the effects of cannabis on hippocampal functioning. The current study involved two experiments. Experiment 1 compared 35 current users of cannabis and 38 well-matched controls on a face-name task, previously shown to activate the hippocampal region. Based on the results of experiment 1, experiment 2 used fMRI and a modified version of the face-name task, to examine cortical and (para)hippocampal activity during learning and recall in 14 current users of cannabis and 14 controls. Results of experiment 1 showed that cannabis users were significantly worse with respect to learning, short and long-term memory performance. Experiment 2 showed that despite non-significant differences in learning and memory performance, cannabis users had significantly lower levels of BOLD activity in the right superior temporal gyrus, right superior frontal gyrus, right middle frontal gyrus and left superior frontal gyrus compared to controls during learning. Results also showed that cannabis users had significantly higher BOLD activity in the right parahippocampal gyrus during learning. Hypoactivity in frontal and temporal cortices, and relative hyperactivity in the parahippocampus identify functional deficits and compensatory processes in cannabis users.
吸食大麻与人类学习和记忆受损以及执行功能方面的问题有关。有人认为，长期吸食大麻者在学习和记忆方面与大麻相关的损伤是由大麻对海马体功能的影响所致。当前的研究包含两个实验。实验1让35名当前的大麻使用者和38名匹配良好的对照组参与一项面孔-名字任务，此前的研究表明该任务会激活海马体区域。基于实验1的结果，实验2使用功能磁共振成像（fMRI）以及面孔-名字任务的一个修改版本，来检测14名当前的大麻使用者和14名对照组在学习和回忆过程中的皮质及（旁）海马体活动。实验1的结果显示，大麻使用者在学习、短期和长期记忆表现方面明显更差。实验2表明，尽管在学习和记忆表现上没有显著差异，但与对照组相比，大麻使用者在学习过程中右侧颞上回、右侧额上回、右侧额中回和左侧额上回的血氧水平依赖（BOLD）活动水平明显更低。结果还显示，大麻使用者在学习过程中右侧海马旁回的BOLD活动明显更高。额叶和颞叶皮质的活动减退以及海马旁回的相对活动亢进表明了大麻使用者的功能缺陷和代偿过程。
