In a study about human memory, brain growth and learning, the first 12 yrs of human growth and learning is very critical to the future brain health.

In contrast, the rats exposed to the shock compartment at 24 days of life learned and retained the memory for a long time and avoided this place—revealing a memory similar to that of adult rats.

Rats develop rapidly during infancy and become sexually mature at about 6 weeks of age. Humans, on the other hand, develop slowly and don’t hit puberty until about age 12-13 years (range: 8 to 16 years).

To address this, the scientists focused on the brain’s hippocampus, which previous scholarship has shown is necessary for encoding new episodic memories. Here, in a series of experiments similar to the box tests, they found that if the hippocampus was inactive, the ability of younger rats to form latent memories and recall them later by reminders as they got older was diminished. They then found that mechanisms of “critical periods” are fundamental for establishing these infantile memories.

A critical period is a developmental stage during which the nervous system is especially sensitive to environmental stimuli. If, during this period, the organism does not receive the appropriate stimuli required to develop a given function, it may be difficult or even impossible to develop that function later in life. Well-known examples of critical period-based functions are sensory functions, like vision, and language acquisition.

The study shows that there is a critical period for episodic learning and that during this period the hippocampus learns to become able to efficiently process and store memories long-term.

“Early in life, while the brain cannot efficiently form long-term memories, it is ‘learning’ how to do so, making it possible to establish the abilities to memorize long-term,” explains Alberini. “However, the brain needs stimulation through learning so that it can get in the practice of memory formation—without these experiences, the ability of the neurological system to learn will be impaired.”

These studies, the researchers observe, suggest that using learning and environmental interventions during a critical period may significantly help to address learning disabilities.