Thyroid hormones are important regulator of brt=ain development during fetal and neonatl periods. Transient disruption of this hormone can impair brain development. The most severe neurologic impairment resulting from thyroid defeciency is endemic cretinism. While many importatnt aspects of brain development occur either before the time of fetal thyroid hormone synthesis or at ease before the synthesis of high levels of fetal hormone, maternal thyroid hormones might be important for brain development events. The majority of biological actions of thyroid hormone appear to be mediated by thyroid hormone receptors, which are ligand dependend transcription factors, Thyroid hormone controlled brain development is regulated by other intervening factors including other hormones, growth factors and transcription factors. Thyroid hormones of maternal orgin can selectively affect gene expression in the fetal brain development
S. Das and Dr. Damodaran Vasudevan, “Influence of Thyroid Hormone on Brain development”, Thyroid Research and Practice, 2005.