"[T]he relocation of neurons from the subplate to the cortical plate also begins around 24 weeks, thus coinciding with the invasion of thalamic afferents. This relocation is extremely rapid from about 34 weeks, leading to the dissolution of the subplate as the extracellular matrix and other growth-related and guidance molecules disappear.21 The subplate has been observed to thin in the insula and in areas where cortical folding occurs rather earlier than the rest of the cortex, from at least 20 weeks. It is currently uncertain whether this thinning is due to earlier maturation and potentially earlier synaptic activity in these regions, some of which are key areas in the experience of pain in adults, 3 or attributable to incidental morphological changes."