The Ecology of Humans (27-2) The Brain Through Life continued

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When a particular brain region that is thought to be essential for a function is lost, other brain regions suddenly are freed to take on the task. ~ American psychologist Michael Fanselow

From birth the mind-brain develops its capacity for perception, voluntary movement, and reasoning. The frontal lobes are especially active during developing the facility for emotional attachments, working memory, and planning. At 5 months babies can perceive facial emotions: a crucial survival skill.

The human brain develops slowly compared with other creatures. The earliest long-term memories form around 3 years of age. Before that the dramatic growth of new neurons disrupts long-term memory formation. Also, the physical instrument for long-term memory – the hippocampus – is still maturing. Long-term memory improves at ~10 years of age, as hippocampal growth slows.

Youngsters are more likely to recall an event if asked about it. This affects when long-term memories begin to reside.

The childhood memories of the Māori of New Zealand typically begin to stick a year earlier than they do for North American children. Among the Māori memories are honored and much discussed. A sense of self (self-awareness) is usually achieved by age 4 among Māori children.

The brain is most adaptive – a literal information sponge – during the formative period from infancy into childhood. This statement seems to conflict with the fact that infant memories are ephemeral: which they are, because the hippocampus is still maturing. The issue is not retention, but patterning.

In infancy, the brain is learning how to learn. What is being learned, and its retention, are largely incidental. What is critical is that the developing brain is actively employed: that the patterns for learning are being established.

Neglect, abuse, or exposure to violence during early childhood can has lifelong consequences, as it affects the physical substrate of the brain. The amygdala and hippocampus are areas especially affected. The childhood brain needs positive stimulation.

High levels of physical activity in the first few years of life stimulates brain development, especially for boys. The language and math skills of the physically active are sharper in the first years of school.

Each processing system has optimal windows of time for learning: where the brain is especially plastic and sensitive, accommodative to rapid growth.

Language manipulation is the most powerful tool a human can possess for social interaction and provides a strong basis for cognitive clarity.

The facility for language is innate, but skill with languages must be acquired. The full formative period for language development begins before birth and lasts to between 8 years and puberty.

Brain structure is shaped by the languages learned early in life. Early musical training builds language skill.

After the critical period, the ability to learn a 2nd language is less easily achieved: the mind-brain has less language plasticity.

Accents are picked up during the language formative period and hard to unlearn afterwards. After the language fast-track window closes, 2nd languages are not even processed in the same way or even the same part of the brain as the native tongue.

Toddlers typically learn more quickly than adolescents because the number of connections among synapses is 50% greater in an immature brain than in the adult brain.

The brain consumes its peak energy at age 5. 2/3rds of body’s resting energy expenditure goes to the brain, and almost half altogether. Relative brain energy consumption declines with age.

Human children evolved a much slower rate of childhood growth compared to other mammals and primates in part because their brains required more energy to develop. ~ American anthropologist Christopher Kuzawa

By age 6 the brain has reached 95% its adult weight and is just past its peak energy consumption. Between the ages of 6 to 13 the brain goes through growth spurts that affect understanding language and spatial relationships, and provide intellectual and social skill development, such as the ability to read and make friends.