Data from: Effect of mild thyrotoxicosis on performance and brain activations in a working memory task

Aims: Disturbed levels of thyroid hormones are associated with neuropsychiatric disorders, including memory impairments. The aim of this study was to evaluate effects of mild induced thyrotoxicosis on working memory and its neural correlates. Methods: Twenty-nine healthy, male subjects with normal thyroid state participated in the study. Functional MRI was acquired during a working memory task (n-back task) before and after ingesting 250 μg L-thyroxin per day for a period of eight weeks. In addition, neuropsychological tests were performed. Results: In the hyperthyroid condition the subjects showed slower reaction times, but a higher accuracy in the 0-back version of the memory tasks. Fewer differences between euthyroid and hyperthyroid state were seen for the more difficult conditions of the n-back task. FMRI revealed effects of difficulty in the parahippocampal gyrus, supplementary motor area, prefrontal cortex, anterior cingulate cortex, posterior cerebellum, rolandic operculum and insula (p<0.05, FWE corrected). When comparing euthyroid and hyperthyroid condition in relation to task-induced activation, differences of activation were found in the right prefrontal cortex as well as in the right parahippocampal area. In the psychological assessment, the alerting effect in the Attention Network Task (ANT) and four out of five parameters of the auditory verbal learning test (AVLT) showed an increase from euthyroid to hyperthyroid state. Conclusions: It can be concluded that even a short-term intake of thyroid hormones leads to an activation of brain areas associated with working memory and to an improvement of accuracy of working memory tasks.研究目的：甲状腺激素水平紊乱与包括记忆损害在内的神经精神疾病密切相关。本研究旨在探讨轻度诱导性甲状腺毒症对工作记忆（working memory）及其神经关联的影响。 研究方法：本研究共纳入29名甲状腺功能正常的健康男性受试者。在每日口服250微克左甲状腺素（L-thyroxin）、持续8周前后，分别采用工作记忆任务（n-back task）进行功能磁共振成像（functional MRI）数据采集。此外，本研究还开展了神经心理学测试。 研究结果：相较于甲状腺功能正常状态，受试者在甲亢状态下的反应时更长，但在0-back记忆任务中的准确率更高。对于n-back任务中难度更高的条件，甲状腺功能正常与甲亢状态之间的差异较小。功能磁共振成像结果显示，任务难度对海马旁回、辅助运动区、前额叶皮层、前扣带回皮层、小脑后部、罗朗多岛盖（rolandic operculum）及岛叶均产生显著影响（p<0.05，FWE校正）。对比甲状腺功能正常与甲亢状态下的任务诱发激活模式，右侧前额叶皮层及右侧海马旁区均存在激活差异。在神经心理学评估中，注意网络任务（Attention Network Task, ANT）的警觉效应以及听觉语言学习测试（auditory verbal learning test, AVLT）5项参数中的4项，均在从甲状腺功能正常状态转为甲亢状态时出现升高。 研究结论：本研究结果表明，即使短期摄入甲状腺激素，也可激活与工作记忆相关的脑区，并提升工作记忆任务的准确率。