plasticity

Neural Plasticity
- Definition: Neural plasticity refers to the brain's ability to change and adapt its structures and processes in response to experience and new learning. This concept links to functional recovery, which involves the reallocation or redistribution of certain abilities after brain damage or trauma.

Plasticity
- Description: The brain's tendency to change and adapt due to experience and new learning. This generally involves the growth of new connections.
Functional Recovery
- A specific form of plasticity where after trauma, the brain is able to redistribute or transfer functions usually performed by damaged areas to other undamaged areas.

Research Example: Comparison Between Brain Volumes
- Researchers studied the hippocampal volume of taxi drivers (who navigate varying routes) compared to bus drivers (who follow fixed routes).
- Statistical Analysis: An unrelated t-test showed significant difference at the p < 0.05 level between the two groups.

Why was the unrelated t-test appropriate for this research? (4 marks)
- Two independent groups (taxi and bus drivers) were being compared which requires an unrelated t-test.
- The data collected from both groups were not dependent on each other.
What does 'significant difference was found at the 0.05 level' mean? (2 marks)
- This indicates that there is a less than 5% probability that the observed differences are due to chance, supporting the idea that the differences in hippocampal volume are statistically significant.

Brain Plasticity
- The brain has metaphorically been said to be "plastic" due to its capacity for change throughout life.
- In infancy, the brain grows rapidly, creating approximately 15,000 synaptic connections per neuron by the age of 2-3 years.
- Synaptic Pruning: Rarely used connections are eliminated while frequently used ones are strengthened, allowing for more efficient neural pathways.

Modern research illustrates that the adult brain also retains the capability for plasticity, adapting and forming new connections in response to learning and external demands.

Eleanor Maguire et al. (2000)
- Finding: Increased grey matter in the posterior hippocampus of London taxi drivers compared to a matched control group.
- Significance: This area is associated with spatial navigation, and the study established that learning enhances brain structure.
- Correlation: Greater experience in the job correlates with more pronounced differences in brain structure.
Bogdan Draganski et al. (2006)
- Research showed brain imaging of medical students pre- and post-exams, indicating structural changes in the posterior hippocampus and parietal cortex.

Post-Injury Brain Adaptation
- After trauma (like a stroke), the brain can adapt, allowing intact areas to take over functions from damaged regions.
- Spontaneous Recovery: Initial rapid recovery process that eventually slows down, necessitating rehabilitative therapy.

Rewiring and Reorganisation:
- The brain forms new synaptic connections surrounding the area of damage, activating secondary pathways to sustain function.
Structural Changes Supporting Recovery:
- Axonal Sprouting: Growth of new nerve endings connects undamaged nerve cells, forming new pathways.
- Denervation Supersensitivity: Similar axons increase activity to compensate for lost connections, potentially leading to discomfort or pain.
- Recruitment of Homologous Areas: Similar areas on the opposite side of the brain can assume the functions of damaged regions, e.g., if Broca's area on the left is damaged, the right equivalent may adapt its functions.

Functional recovery showcases the brain's adaptability and can be discussed alongside plasticity in academic discussions.

Limitations:
- Adaptation can have negative consequences, such as reduced cognitive functioning resulting from prolonged drug use (Medina et al. 2007).
- Phantom Limb Syndrome: Occurs in 60-80% of amputees, where sensations persist in the missing limb due to cortical reorganisation (Ramachandran and Hirstein 1998). This indicates that not all adaptive changes are beneficial.

Generally, the ability to exhibit plasticity diminishes with age.
Ladina Bezzola et al. (2012): Study found older adults (ages 40-60) demonstrated increased efficiency in motor cortex activity following 40 hours of golf training, suggestive of continued plasticity.

Research indicates the possibility of seasonal plasticity responding to environmental changes, particularly in animals (e.g., changes in the suprachiasmatic nucleus affecting sleep/wake cycles).
- Most studies primarily conducted on animals, raising questions about relevance to human behavior.

Research on brain plasticity aids neurorehabilitation efforts, emphasizing therapies such as constraint-induced movement therapy for motor recovery post-stroke.
Knowledge of axonal growth encourages innovative therapy development, enhancing recovery outcomes.

The concept of cognitive reserve implies that educational attainment can influence recovery rates. Schneider et al. (2014) revealed that individuals with more education have higher rates of disability-free recovery (DFR) after brain injury.

While promising, new treatment studies (e.g., stem cell research) frequently use small sample sizes and may lack control groups, which can limit generalizability (e.g., Soma Banerjee et al. 2014).

Meditation may impact brain structure/function significantly:
- Sara Lazar et al. (2005): Found thicker cortices in experienced meditators.
- Holzel et al. (2011): Increased grey matter in the left hippocampus linked to mindfulness training.
- Yi-Yuan Tang et al. (2012): Reporting increased white matter in the anterior cingulate cortex after four weeks of meditation.

Questions posed regarding everyday behaviors that may also alter brain structure/function, expanding the understanding of how various practices influence neural plasticity.

Gabby Giffords, a former US politician, demonstrated remarkable recovery following a severe brain injury from an assassination attempt.
- Underwent a waking coma and progressed to walking and communication through rehabilitation.
This case exemplifies extraordinary brain plasticity and emphasizes the potential for recovery through consistent rehabilitation.

Strengths and limitations of using case studies are to be considered in light of findings on brain recovery, particularly in assessing what general conclusions can be drawn from individual cases.

Define 'plasticity' in the brain.
Outline research findings on functional recovery after brain trauma.
**Discuss the implications of research into plasticity and functional recovery of the brain post-trauma.