A1.1.2 – NEUROPLASTICITY

📘 Definition Table

Term	Definition
Neuroplasticity	The brain’s ability to reorganize itself by forming new neural connections throughout life.
Synaptic Plasticity	The process by which synaptic connections strengthen or weaken over time in response to increases or decreases in activity.
Cortical Remapping	When functions previously performed by a damaged area of the brain are taken over by undamaged regions.
Long-Term Potentiation (LTP)	A long-lasting increase in synaptic strength resulting from repeated stimulation.
Dendritic Branching	Growth of new dendritic spines that create additional synaptic connections.
Neurogenesis	The formation of new neurons, especially in the hippocampus and olfactory bulb.
Experience-Dependent Plasticity	Brain structural and functional changes in response to environmental demands and learning.

📌 Introduction

Neuroplasticity describes the dynamic nature of the brain—its capacity to adapt structurally and functionally in response to learning, environmental changes, and injury. Once thought to be fixed after childhood, modern neuroscience has shown that plasticity persists throughout life, enabling recovery from trauma and supporting lifelong learning.

It involves both functional plasticity (the brain’s ability to move functions from damaged to undamaged areas) and structural plasticity (the brain’s ability to change its physical structure through new connections and dendritic growth).

Plasticity is influenced by environmental enrichment, learning, stress, and trauma, and is mediated by neurochemical and molecular changes like LTP and neurotrophin release (e.g., BDNF).

🧩 Mechanisms of Neuroplasticity

Mechanism	Description	Biological Process
LTP (Long-Term Potentiation)	Repeated activation of synapses strengthens synaptic transmission.	Increased neurotransmitter release and receptor sensitivity.
Dendritic Branching	Formation of new dendritic spines, increasing synaptic networks.	Promotes information storage and learning.
Cortical Remapping	Brain reallocates functional areas after injury or experience.	Neighboring regions take over lost functions.
Environmental Enrichment	Stimulating surroundings promote neuron growth.	Increased neurogenesis and synaptic density.
Neurogenesis	Growth of new neurons, primarily in hippocampus.	Linked to memory, learning, and mood regulation.

🧠 Key Studies

1. Maguire et al. (2000)

• Aim: To investigate whether structural changes occur in the hippocampus of London taxi drivers in response to spatial navigation experience.
  
• Method: MRI scans of 16 male London taxi drivers compared with 50 matched controls.
  
• Findings: Increased grey matter volume in the posterior hippocampus of taxi drivers, positively correlated with years of experience.
  
• Conclusion: Experience (navigation) causes structural plasticity; the hippocampus adapts to spatial demands.
  

2. Draganski et al. (2004)

• Aim: To investigate whether learning a new skill (juggling) induces structural changes in the brain.
  
• Method: MRI scans before, during, and after participants learned to juggle over three months.
  
• Findings: Increased grey matter in mid-temporal areas involved in visual motion; decreases after training stopped.
  
• Conclusion: Learning new skills leads to temporary structural brain changes—evidence of experience-dependent plasticity.
  

3. Rosenzweig, Bennett & Diamond (1972)

• Aim: To study the effects of environmental enrichment and deprivation on neuroplasticity in rats.
  
• Method: Rats placed in either enriched (toys, social interaction) or deprived environments.
  
• Findings: Enriched rats developed thicker cerebral cortices and higher acetylcholine activity.
• Conclusion: Enriched environments enhance brain growth and synaptic complexity—environment affects neural development.
  
  
  

4. Merzenich et al. (1984)

• Aim: To examine cortical remapping in the somatosensory cortex after sensory deprivation in monkeys.
  
• Method: Fingers of monkeys were amputated; cortical responses were measured using microelectrodes.
  
• Findings: Adjacent cortical areas took over the region previously responsible for the amputated finger.
  
• Conclusion: The brain reorganizes functional mapping following injury—demonstrating cortical plasticity.
  

🔍 Evaluation

Strengths

• Empirical evidence from MRI and animal studies supports both structural and functional plasticity.
  
• Cross-species consistency (rats, monkeys, humans) enhances theoretical reliability.
  
• Applications to rehabilitation and education are significant.
  

Limitations

• Causation cannot always be inferred (e.g., taxi drivers may have had larger hippocampi to begin with).
  
• MRI studies show correlation, not process.
  
• Animal research raises ethical concerns regarding deprivation and harm.
  

Ethical Considerations

• Use of animals (Rosenzweig, Merzenich) must adhere to minimization of harm and proper housing.
  
• Human studies like Maguire are non-invasive and low-risk, aligning with IB ethical guidelines.
  

💬 Theory of Knowledge (TOK) ConnectionNeuroplasticity challenges the deterministic view of the brain.Knowledge Question: To what extent can scientific evidence of brain plasticity support the idea of free will? If the brain changes with experience, are behavior and personality truly fixed? This raises TOK debates between biological determinism and personal agency—bridging neuroscience with philosophy.

❤️ CAS LinkStudents can engage in service projects promoting neurorehabilitation or mental agility in aging populations — such as organizing “Brain Fitness” workshops that involve memory games, puzzles, or mindfulness sessions to demonstrate neuroplastic change through experience.

🧪 IA LinkAn IA could explore memory recall improvement through practice, linking behavioral changes to potential neural adaptation. For example, replicating aspects of Maguire or Draganski by testing participants on spatial or skill-based tasks over time.

🌍 Real-World ConnectionStroke Recovery: Therapies like constraint-induced movement therapy rely on cortical remapping to restore motor control. Education: Learning techniques that encourage repeated practice and spaced recall stimulate long-term potentiation. Mental Health: Cognitive-behavioral therapy (CBT) physically alters neural pathways involved in emotion regulation. Technology: Neurofeedback and brain-computer interfaces harness plasticity to enhance rehabilitation.

🧠 Examiner TipIn Paper 1 SAQs, focus on:Define neuroplasticity. Explain how it occurs (LTP, dendritic branching). Support with one study (Draganski or Maguire). Discuss one strength or limitation. Avoid confusing neuroplasticity with localization — emphasize change over time rather than fixed structure-function mapping.