lecture recording on 11 March 2025 at 13.22.19 PM

Quiz and Study Information

• Upcoming Quiz: Focus on the ascending and descending pathways of the brain.

  • Format: The quiz will consist of multiple-choice questions only.

  • Date: The quiz will take place during class on Thursday.

  • Study Materials: A comprehensive study guide has been posted on Canvas. It is highly recommended to review this document thoroughly prior to the quiz.

  • Instructor Support: The instructor offers office hours for additional assistance. Students are encouraged to attend these sessions for any clarifications or additional help regarding the material.

Brain Structure Overview

• Ventral vs. Dorsal Side: It is crucial to identify the sides of the brain for understanding brain functions; the dorsal side is specifically noted as it plays a role in integrating sensory information.

• Key Anatomical Features:

  • A central line in the brain is recognized for its relevance to overall brain structure.

  • Indentations known as gyri (plural of gyrus) are significant as they increase the surface area for neuronal connections.

Brain Development Stages

• Weight Progression:

  • At birth, the average brain weight is approximately 200 grams.

  • By the first year, it grows significantly to around 1,000 grams, reflecting rapid brain development.

  • In adulthood, the brain stabilizes at approximately 1,200 to 1,400 grams, indicating matured structure and function.

Fertilization and Early Development

• Fertilization Process: Fertilization occurs when sperm successfully fertilizes an egg, forming a zygote (a single cell that will develop into a new organism).

• Cell Division: This process commences within 12 hours post-fertilization, leading to rapid cell division: 1 cell → 2 → 4 → 8 → 16 → 32, exhibiting exponential growth.

• Embryonic Development:

  • By day 7, the embryo demonstrates the formation of three primary cell layers: ectoderm, mesoderm, and endoderm, each contributing to specific bodily systems.

Tissue Development

• Tissue Origins:

  • Ectoderm: The outermost layer that will develop into the brain and nervous system.

  • Mesoderm: The middle layer responsible for forming muscles, bone, and connective tissues.

  • Endoderm: The innermost layer that gives rise to internal organs, such as the gastrointestinal tract.

Neural Development Process

• Neural Development Initiation: Development begins in the ectoderm, leading to the formation of the neural tube, critical in forming the central nervous system.

• Stages in Neural Development:

  • Neurogenesis: The birth of new neurons takes place from non-neuronal cells in the ventricular zone, a highly regulated process.

  • Cell Migration: Newly formed cells migrate to their designated locations, guided by chemokines. Some cells remain in their original position and continue to divide, while others actively migrate.

Differentiation and Specialization

• Cell Differentiation: Cells become specialized, acquiring distinct characteristics based on genetic expression and their environment.

  • Neurons: Neurons develop specific features such as axons (for transmitting signals) and dendrites (for receiving signals).

  • Stem Cells: These are undifferentiated cells capable of becoming various cell types depending on environmental cues, retaining potential for regeneration.

Synaptogenesis and Connectivity

• Synaptogenesis: This process involves the formation of synaptic connections between neurons, establishing crucial communication pathways. In the initial phase, a large number of synapses are produced.

• Apoptosis: Programmed cell death occurs to eliminate excess neurons, refining neural networks according to synaptic connections that are deemed essential.

Neurotrophic Factors

• Neurotrophic Factors: These are chemical signals that play a vital role in determining neuron survival and connectivity. They ensure that neurons connected to existing cells receive necessary nourishment, supporting their functional integrity.

Synaptic Remodeling

• Survival and Optimization: After apoptosis, surviving neurons undergo synaptic remodeling to reorganize synaptic connections, optimizing the neural networks for efficient processing.

• This ongoing process continues well into childhood and beyond, supporting cognitive development and learning throughout life.

Active Learning and Brain Engagement

• Active Learning: Engaging the brain in learning activities reinforces neural connections, demonstrating that continuous learning and mental engagement are crucial for cognitive enhancement throughout the lifespan.