It seems obvious that your toddler’s brain is controlling his behavior. What is not so obvious to the casual observer is that changes in the toddler’s brain lead to more complex behaviors. It can be hard, in other words, to believe that all this nurturing works. What’s exciting for parents is that we have concrete evidence that it does. Starting in the first year, and continuing throughout childhood, there are examples of how changes in the structure of the brain are related to changes in behavior. Early experiences create a more efficient brain, which, in turn, enables your toddler to use the word “juice” when he wants a drink and to stop himself from throwing a toy when he can’t get it to work. We outline three of the most dramatic examples, below:
Energy Usage Harry Chugani, pediatric neurobiologist at Wayne State University, has found that a baby’s brain devotes more energy to the areas responsible for the greatest growth. It’s difficult to tell whether the changes in usage stem from changes in activity, or vice versa, but it is clear that the behavior you see in a baby is related to the activity in his brain:

• Prior to three months, much of your baby’s behavior is based on reflexes. At this time, the majority of energy is used by subcortical areas, such as the brain stem – the area responsible for controlling reflexes.

• After the third month, your baby begins to reach for everything in sight. At this time, energy activity is increasing around the thalamus – the area responsible for reaching movements.

• Around eight months, your child is beginning to demonstrate higher level intellectual functioning (such as a knowledge of the permanence of objects). At this time, energy activity is increasing in the prefrontal cortex – the area responsible for higher level processes.

Language One of the clearest examples of the relationship between brain development and behavior is demonstrated with language. In adults, the processing of language takes place primarily in the left hemisphere. This is not the whole story, however, with young children. While toddlers do tend to process language in the left hemisphere, the right hemisphere is also involved; the complete specialization of brain structures does not occur until much later, perhaps not even until early adulthood. As your toddler reaches various language milestones, there is a dramatic change in the organization of language-relative brain systems; with each jump in language ability, the brain becomes more specialized for processing language. KEY-POINT: “Growth in language skills is directly related to changes in a toddler’s brain.”

Response Inhibition Developmental psychologists now believe that one of the major advances a toddler makes during the second year of life is his ability to stop himself from doing things. Take the example of separation anxiety. Many children develop this anxiety around the end of the first year, and then seem to get over it later in the second year. Researchers believe that this transition is related to a toddler’s developing ability to inhibit an initial response – in this case, reacting with fear – as a parent leaves. It has been shown that these types of emotional reactions are generated in the right hemisphere of the brain. In order for a toddler not to act upon this immediate impulse, an inhibitory signal has to be received from the left hemisphere. The timing of a child’s ability to inhibit behaviors coincides almost perfectly with the development of fibers in the corpus callosum – the part of the brain that enables the right and left hemispheres to communicate. Scientists now believe that this development enables the inhibitory signals to be sent and received, so that a toddler can now stop himself from acting on impulse.