Development and the brain
The zebra finch genome project [3] has revealed that
nearly 10,000 genes are expressed in the forebrain of
juvenile birds (50 days after hatching; within the critical
period for vocal learning) and adult birds, with an overlap
of approximately 91% across these age groups. These
results indicate that up to 60% of the genes in the genome
are expressed in the brain at any one given time. These
findings also suggest that a significant fraction of proteincoding
genes (9%) are developmentally regulated in the
songbird brain, consistent with previous observations
obtained with forward genetic approaches.