Danielle,
Thanks for the wonderful sensitive period examples! These are especially nice because they invoke such a diversity of physiological systems underlying the sensitivity of the period. But all of your examples focus on quite young children and arise from periods of very rapid development. Can you think of examples that occur at older ages?
I sometimes think the aftermath of major acute events is a sensitive period -e.g., I believe there is unusually active cortical reorganization after stroke, with new areas of the brain very actively recruited to solve a problem previously handled by the area affected by the stroke. Any other examples?