Thyroid hormone in utero and vision

This morning, at the annual meeting of the linkurl:American Thyroid Association,;http://www.thyroid.org/ann_mtg/2007_78th/index.html I was captivated by a talk that included a very resourceful experimental design. linkurl:Joanne Rovet's;http://www.sickkids.on.ca/RovetLab/default.asp group, at the Hospital for Sick Children in Toronto, described her research on the effects of hypothyroidism in pregnant women on the visual processing of their babies. Rovet's group found that babies exposed to low thyroid hormone in utero ended up with reduced contrast sensitivity, while visual acuity remained unaffected. This means that as visual processing splits in the brain into the magno and parvo pathways, just the magno pathway, in which contrast is processed, gets affected by low thyroid levels. The findings are interesting, and I'd like to know just what thyroid hormone targets in the magno pathway contribute to the reduced ability to resolve contrast in these babies. But what was particularly interesting about Rovet's study was how she designed it -...