This is a period when he's learning a great deal and when the maid can not supply the right stimulation kids development is going to be slightly slower. (maijasmommymoments.com)
The right stimulation i.e. infant brain exercises also boost infant cognition. (growingwithnemit.com)
Stem cells were hailed as the saviour of damaged hearts, but now it seems that the heart might mend itself — with the right stimulation. (newscientist.com)