Brain Development Notes

What is Development?

  • Development is normative, non-reversible, relatively stable, and sequential.

Brain Development: Prenatal

  • Rapid brain changes occur: neural cells divide, migrate, and interconnect.

  • Neurulation: Neural tube forms (brain/spinal cord).

  • Neurogenesis: Rapid neuron creation.

  • Brain divides into forebrain, midbrain, and hindbrain, with forebrain becoming cortex.

  • Synaptogenesis: Connections develop; unnecessary ones are pruned.

  • Myelination: Fatty insulation develops, speeding conduction. Both synaptogenesis and myelination continue post-birth.

  • Hebb's Law: "Neurons that fire together, wire together."

Brain Development: Infancy

  • Functional development relies on experience.

  • Motor neuron inhibition starts around 3 months.

  • Visual processing enhances; memory regions grow.

  • Mirror neurons enable imitation.

  • Brain reaches 75% of adult weight by age 2, 90% by age 5. Pruning shapes vision, audition, language.

  • Prefrontal cortex matures slowly, causing limitations.

Brain Development: Childhood

  • Brain size increases due to myelination.

  • Myelination and pruning increase information transfer efficiency, improving memory and thought processes.

Neural Plasticity

  • Brain adapts to environment.

Adaptive Change

  • Rich environments enhance cognition.

Critical Periods

  • Plasticity decreases with age. Early exposure is crucial for development (e.g., language, vision).

Maladaptive Change

  • Negative experiences (stress, abuse) harm brain development via hormones like glucocorticoids.

  • Touch is crucial; lack of it impairs development.

Developing Selective Attention

  • Attention develops early, becoming 'sticky' from 1-3 months.

  • From 4-6 months, infants prefer novel events.

  • Attention span increases with age.

Perceptual Development

  • Intersensory redundancy enhances attention and object unity.

The Intersensory Redundancy Hypothesis

  • Redundancy promotes attention to amodal information.

Object Perception

  • Understanding objects retain shape/solidity is key.

  • Movement cues aid object continuity perception.

Depth Perception

  • Depth cues (linear perspective, etc.) and physiological cues (vergence, motion) are used.

The Visual Cliff Experiment

  • Depth perception develops around 6-14 months with motor experience.

Developing Executive Function

  • Executive function controls attention, planning.

  • Inhibition develops in early childhood.

Adult Development

  • Lifespan psychology views development as gains and losses.

Brain Changes

  • Brain weight decreases; gray matter volume declines (reduced by fitness).

Sensory Changes

  • Reduced contrast and hearing sensitivity occur.

Psychomotor Slowing

  • Processing speed slows with age.

Changes in Intelligence

  • Fluid intelligence (problem-solving) declines; crystallized intelligence (knowledge) remains stable or increases.

Changes in Memory

  • Working memory capacity reduces, impacting cognitive processes.

  • Retrieval of memories declines more than encoding.

Seattle Longitudinal Study

  • Most people don't show significant mental decline as they age; cognitive decline may indicate impending death.

Individual Differences

  • Use it or lose it: capabilities atrophy without use.

  • Social life, education, and healthy habits predict healthy aging.