TG and hypothyroidism: The thyroid hormone plays an essential role in early stages of brain development (Cuevas et al., 2005), and structures including the hippocampus, striatum and cortex are reported to be abnormal in rats (Rami et al., 1986), mice (Gil-Ibañez et al., 2013) and children (Clairman et al., 2015) with hypothyroidism.