Division of Psychology, Graduate School of Letters, Hokkaido University, Japan.
Physiol Behav. 2013 Mar 15;112-113:90-5. doi: 10.1016/j.physbeh.2013.02.019. Epub 2013 Mar 6.
Thyroid hormones (THs) are essential for proper brain development in mammals. TH insufficiency during early development causes structural and functional abnormalities in brain leading to cognitive dysfunction. The specific effects of developmental hypothyroidism on attention have not been well characterized in animal models. The present study was conducted to characterize the effects of developmental hypothyroidism on attention in rats, and tested the hypothesis that the hypothyroidism has adverse impacts on attention by means of a visual signal detection task. Pregnant rats were exposed to the anti-thyroid drug, methimazole (0.02% w/v) via drinking water from gestational day 15 through postnatal day (PND) 21 to induce maternal and neonatal hypothyroidism. Male offspring served as subjects for the task started on PND 90. A light stimulus (500 ms, 250 ms or 50 ms) was presented in signal trials and not in blank trials. The offspring were required to discriminate these signal events, and subsequently press the correct lever. The correct response for signal and non-signal events was considered as hit and correct rejection, respectively. The hypothyroid offspring exhibited a decreased hit response for short signals (250 ms and 50 ms) which requires the higher attentional demand. The total number of lever responses during inter-trial interval (ITI) was also increased in the hypothyroid group. The number of lever responses was negatively correlated with a hit response at 50 ms, not at 250 ms. These results suggest that developmental hypothyroidism disrupts signal detection performance via impairment of visual attention and the altered lever response behavior.
甲状腺激素 (THs) 对哺乳动物的大脑正常发育至关重要。早期发育过程中 TH 不足会导致大脑结构和功能异常，从而导致认知功能障碍。在动物模型中，尚未很好地描述发育性甲状腺功能减退症对注意力的具体影响。本研究旨在描述发育性甲状腺功能减退症对大鼠注意力的影响，并通过视觉信号检测任务检验甲状腺功能减退症通过损害视觉注意力和改变杠杆反应行为来影响信号检测表现的假设。从妊娠第 15 天到产后第 21 天，通过饮用含抗甲状腺药物甲巯咪唑（0.02%w/v）的水使怀孕的大鼠暴露于抗甲状腺药物中，以诱导母体和新生儿甲状腺功能减退。雄性后代从第 90 天开始进行任务。在信号试验中呈现光刺激（500 ms、250 ms 或 50 ms），而在空白试验中不呈现光刺激。要求后代区分这些信号事件，然后按下正确的杠杆。信号和非信号事件的正确反应分别被认为是击中（hit）和正确拒绝（correct rejection）。甲状腺功能减退症的后代对需要更高注意力需求的短信号（250 ms 和 50 ms）表现出较低的击中反应。甲状腺功能减退症组在试验间隔期间（ITI）的杠杆反应总数也增加了。杠杆反应次数与 50 ms 的击中反应呈负相关，而与 250 ms 的击中反应无相关性。这些结果表明，发育性甲状腺功能减退症通过损害视觉注意力和改变杠杆反应行为来破坏信号检测表现。
