Study Unit 1: part 3 (HMSC 112)

Brain Development

Stages of Brain Development

• At Birth: The human brain is approximately 25% of its adult size, with around 100 billion neurons present. The neural structures are still forming. Basic sensory and motor functions start to develop.

• 1 Month: Rapid growth occurs; neurons continue to form synaptic connections. The infant begins to show basic reflexes and can respond to stimuli.

• 3 Months: Infants begin to develop more sophisticated motor skills; they can grasp objects and visually track movements. Neurons continue to connect, and synaptic density increases significantly.

• 15 Months: By this age, toddlers are exploring their environments, showing increased cognitive abilities. Language skills begin to emerge, along with enhanced social interactions and emotional responses.

• 24 Months: The brain reaches about 80% of its adult size; toddlers can form sentences and show improved motor coordination. This demonstrates complex thought processes.

• Old Age: In the later stages of life, neural connections may begin to decline, and cognitive functions can slow down. However, mental stimulation and healthy lifestyle choices can mitigate some effects of aging on brain function.

Key Concepts through Age

• Neuronal Complexity through the Lifespan: As individuals progress through life, the complexity and efficiency of neuronal connections evolve, with a notable increase in synaptic density during infancy and childhood. This complexity enables more advanced learning and social interactions.

• Mental Disorders and Their Emergence:

  • ADHD: Often diagnosed in childhood, characterized by difficulties with attention and hyperactivity.

  • Autism: Typically recognized during early childhood, impacting social communication and behaviour.

  • Schizophrenia: Generally manifests in late adolescence to early adulthood, characterized by distortions in thinking and perception.

  • Anxiety Disorders: Can develop at any age, often manifesting as excessive worry or fear responses.

  • Mood Disorders: Including depression, these can appear as early as childhood or adolescence.

  • Impulse-Control Disorders: Typically emerge in childhood or adolescence, involving difficulties managing impulses.

Developmental Processes

• Neuronal Migration: This crucial process involves the movement of neurons from their origin to their destined locations within the brain. This is foundational for proper brain structure.

• Axonal and Dendritic Growth: Refers to the growth of axons (long projections from neurons) and dendrites (branch-like structures), enhancing the connections between neurons and facilitating communication.

• Programmed Cell Death: A natural process where excess neurons and synapses are eliminated, streamlining neural pathways and increasing efficiency in brain function.

• Synaptogenesis: The formation of synapses is a critical process allowing neurons to connect and communicate, significantly influencing learning and memory.

• Myelination: Involves the wrapping of axons with myelin, which acts as insulation, enabling faster signal transmission and improving overall cognitive processing.

• Process Modeling/Synaptic Refinement: This ongoing process enhances the efficiency of communication between neurons over time, allowing for improved cognitive functions and learning.

Microbiota Stability

• Prenatal Influence: The relationship between gut microbiota and brain development begins before birth, and early exposure to a diverse microbial environment can positively influence neural development and subsequent mental health.

Windows of Opportunity

• Critical Stages: There are sensitive periods during brain development when certain types of stimulation are essential for optimal neural growth. Lack of appropriate stimulation during these crucial stages can impede the full potential of neural connectivity.

• Analogy to Muscle Growth: Similar to muscles, the brain grows and strengthens through use and stimulation, emphasizing the need for a rich learning environment.

Motor Development

• Windows of Opportunity for Motor Development:

  • Gross Motor: Refers to the development of large muscle groups, enhancing abilities like crawling, walking, and running as children grow.

  • Perceptual-Motor: Involves the integration of visual and motor skills, essential for coordination and overall physical development.

  • Fine Motor: Involves the use of small muscle groups for precise movements, such as grasping small objects or using utensils, which develop as children age.

Key Developmental Areas

• Maturation of Visual Perceptual Mechanisms: Vision develops through stages, with adults typically experiencing a greater ability to interpret visual information influenced by prior experiences.

• Age-based Development in:

  • Vision: The ability to see and interpret visual stimuli increases with age.

  • Math Logic: Logical reasoning and numerical understanding become refined through educational interactions.

  • Vocabulary: Language skill development shows significant growth during early childhood, impacting future communication abilities.

  • Music: Exposure to music enhances cognitive skills and brain development in children.