Thyroid hormones are essential for neonatal brain development. It is well established that absence of thyroid hormones during critical periods of development can alter sensory functions such as visual and auditory processing, but there are few studies on rat somatosensory system development at mild, long-term, and irreversible neonatal hypothyroidism. Thus, the current study was conducted to investigate whether chronic thyroid hormone insufficiency would alter different cognitive aspects of tactile information processing and sensory motor filtering at behavioral or neuronal levels. Neonatal Wistar male rats were exposed to 0 and 6 ppm of propylthiouracil for 150 days. Behavioral tests including tactile discrimination tests and acoustic startle reflex test were performed. Using extracellular single unit recording technique, barrel cortex neurons' excitatory and inhibitory responses to controlled displacement of whiskers were evaluated. Results indicated that percentage of correct choice in tactile learning and discrimination of a new texture decreased in hypothyroid group compared to the control group (P < 0.05). In addition, acoustic startle reflex of hypothyroid group significantly decreased compared to the control rats when the prepulse intensity was 71 dB (P < 0.05). Data obtained from electrophysiological tests showed that spontaneous activity and response magnitude of barrel cortex neurons decreased in hypothyroid group compared to the control group (P < 0.05). It is concluded that, thyroid hormones can regulate tactile and auditory sensory processing in male rats, and mild and long-term absence of these hormones can result in deficiency in natural functions of these sensory systems.

中文翻译：

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轻度和慢性新生儿甲状腺功能减退对啮齿动物模型中感官信息处理的影响：一项行为和电生理研究。

甲状腺激素对于新生儿脑部发育至关重要。众所周知，在发育的关键时期甲状腺激素的缺乏会改变诸如视觉和听觉处理等感觉功能，但是很少有关于在轻度，长期和不可逆转的新生儿甲状腺功能减退症下大鼠体感系统发育的研究。因此，当前的研究旨在调查慢性甲状腺激素功能不足是否会改变行为或神经元水平的触觉信息处理和感觉运动过滤的不同认知方面。将新生Wistar雄性大鼠暴露于0和6 ppm的丙基硫氧嘧啶150天。进行了包括触觉辨别测试和听觉惊吓反射测试在内的行为测试。使用细胞外单单位记录技术，评估了桶状皮质神经元对晶须受控位移的兴奋性和抑制性反应。结果表明，与对照组相比，甲状腺功能减退组的触觉学习正确选择和新质地识别的百分比降低（P <0.05）。此外，当预搏强度为71 dB时，甲状腺功能减退组的听觉惊吓反射与对照组相比明显降低（P <0.05）。从电生理测试获得的数据表明，与对照组相比，甲状腺功能减退组的桶状皮质神经元的自发活动和反应强度降低（P <0.05）。结论是，甲状腺激素可以调节雄性大鼠的触觉和听觉感觉过程，