Parts of our brains and bodies 'lock' after various critical periods. What keeps those body parts locked after the critical period closes?
For example, our limbs stop growing at a certain length or our brains lose plasticity to acquire some specific skills. We've seen experimental data with valporic acid and other hdac inhibitors re-open critical periods in the brain . Is this the same mechanism (histone deacetylation) by which brain structures or limbs are locked into place?