Significance

Much like a sponge, a newborn's brain is eager to soak up information. The first 3 years of life are regarded as a critical period because that's when subject matter is easiest to absorb and when the brain grows at its fastest pace. Brain cells make connections or synapses when a child is called upon to think -- even when it's something as simple as deciding if she's hungry or choosing a toy to play with. More experiences and thoughts lead to stronger synapses and brain growth. Areas of the brain grow at different times, which helps explain why it might be easier for a 3-year-old to learn a second language than it is for him to control his temper.

Neuron Development

The brain's nerve cells, or neurons, develop and gain strength as your baby grows. The brain follows what the American Academy of Pediatrics describes as a "dynamic dance" between nature and nurture, or DNA and life experience, that molds the structural design of the developing brain. Some brain advances take place without any outside help or encouragement. For example, the brain automatically signals a child to move her mouth when she learns to speak, explains Jandy Jeppson, master's student in develomental studies with a bachelor's in marriage, family, and human develoment from Brigham Young University, writing in an online piece for Purdue University. But to speak, a child must first be spoken to and exposed to words. The brain leaves that part of the developmental process up to parents or caregivers.

Forebrain

The forebrain is the heavy hitter of the central nervous system. As the largest and most sophisticated area of the brain, the forebrain bears responsibility for all brain functions except involuntary or autonomic activities of the brain stem such as a heartbeat, explain Clea McNeely, who has a doctorate in public health, and Jayne Blanchard, writing in "The Teen Years Explained," an online pamphlet published by John Hopkins University. The forebrain houses the cerebrum, which holds the data that makes up a child's personality, intelligence, emotions, speech, reasoning and memory functions. The cerebum is also in control of feeling and movement. The left side of the cerebum is typically associated with cognitive and analytical skills such as language and mathematics while the right side is thought to be responsible for intuitive and creative abilities such as art or music.

Use It or Lose It

Specific brain connections become feeble and fizzle if they're not being put to use. For instance, if your child takes guitar lessons for a couple of years, then quits to pursue other activities, the synapses used to play the guitar weaken. Should your child later decide to resume guitar lessons and faithfully practice, the connections will regain strength, points out Jeppson. The more time that elapses not playing the guitar, the tougher it is to rebuild the connection.