Neuroplasticity & Related Concepts

Neuroplasticity: Core Principles

• "Thinking changes thinking" ➜ cognitive activity literally rebuilds synaptic architecture.
  • Each thought pattern = a firing pattern; repeated firing strengthens wiring ("wiring by firing").
• Brains are dynamic, self-sculpting systems; every moment alters synaptic strength/configuration.
• Book referenced: The Brain That Changes Itself – empirical evidence for lifelong plasticity.

Experience-Expectant vs. Experience-Dependent Plasticity

• Experience-Expectant
  • Species-normal input required during critical periods.
  • Example (implicit): visual cortex needs patterned light early in life.
• Experience-Dependent
  • Individual, lifelong learning; no strict critical period.
  • Two sub-types highlighted:
  1. Map Expansion (sensory input remapping).
  2. Mirror Region Take-Over (inter-hemispheric redundancy).

Map Expansion (Sensory Re-Mapping)

• Definition: Cortical territory for a body part enlarges or shifts when usual afferent input is lost or altered.
• Phantom-Limb demonstration
  • Patient’s hand amputated; touch to cheek produced real tactile perception in missing hand.
  • Mechanism:
  • Somatosensory homunculus: face representation lies adjacent to hand representation.
  • Deafferented hand area seeks input; neighboring face neurons extend synapses ➜ cortical border shifts.
• Philosophical implication: Body image is a brain construction; not fixed to physical tissue.
• Age sensitivity: Younger brains show larger, faster map changes; older brains adapt less.
• Clinical example (video):
  • Patient with painful, permanently "clenched" phantom hand.
  • Mirror-box therapy visually restores hand ➜ unclenches pain via remapped motor/sensory feedback.

Mirror Region Take-Over (Inter-Hemispheric Redundancy)

• Definition: Surviving homologous cortex assumes functions of a damaged/removed region.
• Key example: Rasmussen’s encephalitis hemispherectomy.
  • Jody (surgery at 3 – 4 yrs): right hemisphere removed to stop intractable seizures.
  • Outcomes:
  • Initial left-side paralysis; gradual recovery via left-hemisphere rewiring.
  • Adult life: minimal limp, normal cognition, marriage, career.
• Biological limits
  • Neurons do not regrow en masse; recovery = synaptic rewiring, not neurogenesis.
  • Oldest successful hemispherectomy cited: 12 yrs; adults (e.g., 50 yrs) would lack sufficient plasticity.
• Stroke parallels
  • Recovery probability inversely related to age (e.g., 40-yr-old > 80-yr-old).

Maladaptive Plasticity

• Major Depression
  • Recurrent negative thoughts → reinforced negative circuitry.
• Obsessive–Compulsive Disorder (OCD)
  • Excessive, repetitive firing → deeply entrenched loops; among hardest illnesses to treat.
• Perseveration in anxiety/depression: over-activation solidifies biased networks.

Therapeutic & Self-Improvement Applications

• Cognitive-Behavioral Therapy (CBT)
  • Intentionally creates new firing patterns to overwrite maladaptive wiring.
• Memory Reconsolidation
  • Because recall is reconstructive, deliberately re-imagining events can lay down healthier neural traces.
• Growth Mindset (Carol Dweck research)
  • Belief "I can improve" boosts motivation & actual synaptic change.
  • Inner-city Chicago schools: teaching growth mindset raised performance.
• Mirror-Box Therapy for phantom pain (Ramachandran): visual feedback restores congruent motor-sensory firing.

Factors That Enhance Plasticity

• Learning novel skills/knowledge.
• Physical exercise & overall good health.
• Social interaction.
• Adequate sleep.
• Stress reduction.
• Early intervention for mental-health issues.
• Youth (age < 25 ≈ peak synaptic malleability).
• Adoption of growth mindset.

Factors That Diminish Plasticity

• Chronic stress & high cortisol.
• Sedentary lifestyle, poor health.
• Social isolation.
• Sleep deprivation.
• Untreated mental disorders.
• Advanced age (e.g., > 65).

Key Analogies & Anecdotes

• "Living sculpture": continuous self-carving of neural tissue.
• Jim (double amputee, advanced diabetes)
  • Still "kicks" disliked dog & feels legs because phantom representation persists.
  • Quote: "The only reason I don’t stand up is that I don’t have the courage." — illustrates realism of phantom limbs.

Philosophical & Ethical Takeaways

• Personal responsibility: chosen thought patterns physically mold future selves.
• Early, proactive mental-health treatment prevents maladaptive circuitry.
• Education systems can leverage growth mindset to break socioeconomic fate.
• Rehabilitation strategies must consider age-related limits but also untapped plastic potential.

Quick Reference Equations / Mnemonics

• Plasticity heuristic: \text{Plasticity} \propto \dfrac{1}{\text{Age}} (conceptual).
• Rule of thumb: "Fire together ➜ Wire together."

Use these notes to connect lecture concepts with practical strategies: monitor your thought loops, challenge fixed mindsets, and engage in enriched life experiences to keep sculpting a healthier, more adaptable brain.