Brain Development of Infants and Toddlers

Adapted from “Play’s Role in Brain Development”, D. Bergen,
Association for Childhood Education International, 2000

Most researchers agree on the points below concerning brain development of infants and toddlers:

1. Before birth, 60% of human genes are dedicated to brain development, which is only about 25% completed at birth.
2. The brain works in an interactive and integrated way. The proper comparison is with a jungle, having rich interconnections throughout all of the parts. Specific structures are sensitive to language production and comprehension, as well as social/emotional responses.
3. After birth, 75% of brain development takes place. Experiences during the early years profoundly affect brain structure and performance through adulthood.
4. Brain structures relating to survival and safety develop first. It is likely that the theoretical concept of “stages” of development relate to brain development changes.
5. Brain plasticity and resilience provides some protection against early negative experiences except extreme neglect, abuse, toxins, etc. Plasticity continues through life, experiences affecting its structures and functions.

Ages for Brain Development

Ages Birth –1

1. Most neurons at birth at not connected in networks.
2. Sensorimotor brain areas are most active during the 2-3 month period, frontal lobe active by 6-8 months. Brain weight increases from about 1 to 2 pounds by one year.
3. The visual cortex develops rapidly during the first year.
4. By 12 months, the brain is more similar to the adult.
5. Early play involves practice of the sensorimotor system.
6. The social nature of play is activated by the frontal lobe. Turn-taking games, elaborate practice play and one-word naming of play objects is enjoyed.

Ages 1-2

1. Brain connections expand to about 1,000 trillion-twice the density of the human brain, since the toddler brain is 2 ½ times as active as the adult brain.
2. Brain structures relating to language become active. Brain areas generating social-emotional responses begin to be connected with frontal lobe areas.
3. Initial understanding of emotions begins, while self-control is difficult.
4. Pretend play is seen by age 2, showing the brain is capable of simple, symbolic thought.

Ages 3-8

1. This is the fastest growth period for frontal lobe networks, processing speed increasing.
2. The brain is 90% of its adult weight by age 6.
3. The frontal lobe of the cortex is most dense about age 7.
4. Connections in motor and sensory areas are firmly established. Unused connections are “pruned”.
5. By age 6, games with rules are common play activities, showing extensive symbolic thought capacities, self-regulation, and the ability to explain their behavior.