Human Brain Development

Early Embryo Stage

• 5 Weeks Old:
  • Size: Comparable to an apple seed.
  • Development: Brain begins to grow.
• 8 Weeks Old:
  • Brain Structure: Basic structure of the brain and central nervous system are in place.
  • Neural Networks: Begin spreading out.
  • Nerve Signals: Travel at speeds of more than 150 miles per hour.

Birth

• Neuron Count: Nearly all 100 billion neurons are already present.
• Brain Weight: Approximately 25% of adult weight.

Post-Birth Growth

• Growth Period: Fastest growing period, brain quadruples in size.
• Preschool Age: By preschool, brain reaches about 90% of adult size.

Neural Development

• Neural Connections: 700 new connections formed every second.
• Developmental Milestones:
  • Smiling typically around two months.
  • Talking usually around one year.
  • Dressing oneself around three years old.

Brain Plasticity

• Experience-Driven Changes: Brain changes throughout life due to experience.
• Learning and Growth: Includes speaking, walking, understanding colors/shapes, forming thoughts.

Pruning Process

• Unused Neurons: Neurons not frequently used are eliminated, a process known as pruning.

Influence of Early Experiences

• Early experiences such as first words, first foods, first media exposure, and early arguments can significantly shape development.