An example of the temporal dynamics of the transcriptome in the fetal human brain is a reduction of interhemispheric differences in gene expression during the prenatal stages of development. Significant asymmetry of gene expression between the right and left hemispheres, which is detected at 12 and 14 post-conception weeks (pcw) (T. Sun, et al., 2005), is reduced at 16-17, not detectable by 19 pcw (Johnson, et al., 2009; Lambert, et al., 2011), and is almost undetectable later in adult life (Khaitovich, Muetzel, She, Lachmann, Hellmann, & Dietzsch, 2004).
