Brain development from 12 to 18 months

Why “use it or lose it” is so important to a child’s development.

The phrase “use it or lose it” is often employed in reference to the diminishing cognitive function associated with ageing. But it’s just as apt when it comes to early brain development. During this time, your baby’s brain is rapidly forming new synaptic connections between nerve cells, establishing a dense messaging network that allows for complex mental processing and motor function. The more these neural connections are stimulated, the stronger they become, while less-used neural pathways weaken and die off. That’s why providing an enriching environment with regular verbal and physical stimulation is so important to your baby. Here’s a look at some of the ways their brain (and your encouragement) is fuelling all sorts of new skills right now.

Cognitive

At this point in your baby’s growth, myelination (a process in which the nerve cells establish a thick protective coating that helps speed up brain signals) is in full swing. (One area where the progress of myelination is most apparent is in your child’s increasing memory. Up to now, your baby has been able to recognize familiar objects—a type of memory that involves only one region of the brain: the hippocampus. But after their first birthday, thanks to development in the cerebral cortex, they become able to consciously recall information at will. Eventually, synaptic connections linking the hippocampus and various regions of the cerebral cortex will form and strengthen, allowing for more complex types of memory that involve multiple regions of the brain.

Development of the cerebral cortex at this age also allows for the emergence of higher-order cognitive abilities, including self-awareness. Starting around 15 months, your toddler will begin to recognize that the face they see in the mirror is their own.

Motor

By the end of the first year, your toddler’s cerebellum—the part of the brain responsible for coordination and balance—has tripled in size, which is reflected in the enormous leaps in gross motor skills they are making. In the months following their first birthdays, most toddlers, having become efficient crawlers, learn to pull themselves up to standing and take their first solo steps. You’ll also see your child’s newfound coordination on display in this constant grabbing, dropping, and throwing of toys.

Communication

The areas of the brain associated with language have more synaptic connections than any other part of the brain during this period, causing a leap in language abilities known as the vocabulary explosion. Remarkably, between your child’s first and second birthdays, their vocabulary will quadruple.

Although the parts of the cerebral cortex known as the temporal lobes (which are located on either side of the brain) are most specifically involved in hearing and language, the frontal lobes (which are associated with memory) also play an important role in learning and producing words. By listening and trying to understand your speech, your toddler gives these neural pathways a healthy workout, which stimulates even more advances.

Social

In the months after your toddler’s first birthday, you’ll notice them becoming more engaged with the world around them. The fact that the limbic system (part of the brain that controls emotions) develops before the cerebral cortex figures largely in your baby’s emotional experiences. At 12 to 18 months, your child can process and store emotional events but doesn’t yet have the language and memory skills to consciously consider and express their emotions verbally.

At this age, your baby also interacts with you in more emotional ways; they have learned that smiling, laughing, squealing, and talking all elicit certain reactions from you. This development is fuelled by the maturation of the temporal lobes, which are associated with the ability to read facial cues, interpret emotional signals, and exhibit other aspects of social understanding.