how soon after conception do synapses form
At birth, a babyâs brain contains 100 billion neurons, roughly as many nerve cells as there are stars in the Milky Way, and almost all the neurons the brain will ever have. The brain starts forming prenatally, about three weeks after conception. Before birth, the brain produces trillions more neurons and âsynapsesâ (connections between the brain cells) than it needs. During the first years of life, the brain undergoes a series of extraordinary changes.