Brain plasticity

Neuroplasticity Study Guide

What is Neuroplasticity?

• Definition: The brain's ability to modify its neuron networks.

• Importance: Foundation for learning, memory formation, and adapting to challenges.

• Lifespan Changes: Occurs throughout all life stages including prenatal, childhood, adulthood, and old age.

Fine-Tuning by Experience

• Plasticity in Development: High plasticity during early development, limited in later life.

• Structural Changes: Neurons modify their structure—dendrites grow new spines reflecting new learning.

• Skill Practice: Extensive practice can enhance brain organization for specific skills.

  • Example: Professional musicians show larger temporal lobes and thicker gray matter through MRI studies.

• Over-Reorganization: Can lead to conditions like focal hand dystonia (musicians' cramp).

Mechanisms of Neuroplasticity

• Cell Death: Normal pre-programmed cell death during development.

• Neuroplasticity Mechanisms: Involves molecular processes, synaptic plasticity, cell proliferation, and apoptosis.

• Types of Changes: Short-term versus long-term structural and functional changes in the brain.

Synaptic Plasticity

• Types of Changes: Includes location changes of synapses, long-term potentiation (LTP), and synaptogenesis.

• Role in Learning: Critical for learning and memory.

Structural and Functional Synaptic Plasticity

• Structural Changes: Strength of synapses changes through addition/removal; requires protein synthesis.

• Activity-Dependent Plasticity: Changes correlate with activity patterns of cells.

Hebb’s Rule and Long-Term Potentiation

• Hebb’s Rule: "Cells that fire together, wire together."

• Long-Term Potentiation (LTP): A lasting increase in synaptic strength from specific patterns of activity.

• NMDA Receptors: Essential for LTP; crucial in learning and memory areas.

Mechanisms of LTP

• Phases: Early and late phases involve gene expression and protein synthesis.

Neurogenesis

• Location: Primarily occurs in the hippocampus and subventricular zone.

• Daily Cell Production: About 9,000 new cells produced daily, significant for learning and memory.

• Factors Affecting Neurogenesis:

  • Increase: Glutamate, serotonin, exercise, social interactions.

  • Decrease: Stress, isolation, certain drugs.

Function of Neurogenesis

• Role in Learning: Contributes to memory, role is still being researched.

• Integration and Recovery: Forms the basis for recovery and re-mapping after damage to the nervous system.

Brain Repair Mechanisms

• Behavioral Recovery: Survivors can recover through mechanisms similar to brain development.

• Types of Brain Injuries: Includes TBI, strokes, and infections.

Types of Strokes

• Ischemic Stroke: Caused by blood clots, results in oxygen deprivation.

• Hemorrhagic Stroke: Results from ruptured arteries, leading to blood flooding neurons.

Remarkable Recovery**

• Case Study: Michelle, born with half a brain, shows significant recovery of skills and functions.

• Cortical Reorganization: Adaptations depend on damage type and location.

Axon Regrowth**

• Peripheral vs. Central Damage: Peripheral axons can regenerate; CNS damage is more challenging.

• Cortical Adaptation: The cortex can adjust post-injury or amputation.

Phantom Limb Phenomenon**

• Definition: Sensation of an absent limb continues post-amputation.

• Mechanisms: Involves cortical map reorganization; can lead to phantom pain.

Challenges in CNS Recovery**

• Limited Regrowth: CNS axons face challenges due to scar tissue and inhibitory chemicals.

• Long Recovery Process: Continuous practice is needed, often taking years.

Summary of Neuroplasticity and Brain Damage**

• Ongoing Plasticity: Crucial for lifelong learning and improvement.

• Neurogenesis: Limited to specific areas but important for memory.

• Brain Damage Recovery: Early intervention vital; re-mapping can be beneficial or detrimental.

• Re-learning: Essential effort and practice are necessary for recovery.