I found this fascinating quote today:
But there is another reason why this look of love is important for the newborn. When mother and child share this gaze, the child’s brain is bathed in happy-making brain chemicals like dopamine. This triggers the growth of neurons, and neuron connections, in the brain. Neurons and their connections are what provide us with all of the abilities that our brains give us. When the baby grows neurons as a result of sharing a loving gaze with mom, this leads to the development of the baby’s ability to think, feel, imagine, act and connect with others. The full development and realization of these abilities are the wellspring of happiness. The baby wants to keep going back for more and more of this emotional meal, and each time they do their brain grows and develops in a positive way.Glenn Berger under, Glenn Berger, Ph.D., Apr 2010
You should read the whole article.