Plasticity and Functional Recovery of the Brain

Question 1

Plasticity:

Answer 1

The brain’s tendency to change and adapt functionally and physically as a result of experience and new learning.

Question 2

Functional recovery:

Answer 2

A form of plasticity. Following damage through trauma, the brain’s ability to redistribute or transfer functions usually performed by a damaged areas to other undamaged areas.

Question 3

Synaptic Connections Infancy:

Answer 3

1. During infancy, the brain experiences a rapid growth in the number of synaptic connections.
2. Peaking at approximately 15,000 synapses per neuron at age 2-3 years. (Gopnik et al. 2003)
3. Twice as many as there are in an adult brain.

Question 4

Synaptic Pruning:

Answer 4

Rarely used connections are deleted and frequently used connections were strengthened.

Question 5

Are changes restricted to the developing brain?

Answer 5

1. Thought that the adult brain remained fixed and static in terms of functions and structure.
2. Neural connections can change or new neural connections can be formed at any time in life as a result of learning and experience (plasticity).

Question 6

Eleanor Maguire et al. (2000):

Answer 6

1. Studied the brains of London taxi drivers and found significantly more volume of grey matter in the posterior hippocampus than in a matched control group.
2. Part of the brain associated with the development of spatial and navigational skills in humans and other animals.
3. London cabbies must take a complex test called ‘The Knowledge’ which asses their recall of city streets and possible routes.
4. Learning experience altered the structure of the taxi driver’s brain.
5. The longer they had been on the job, the more pronounced was structural difference (positive correlation)

Question 7

Draganski et al. (2006):

Answer 7

1. Imaged the brains of medical students 3 months before and after their final exams.
2. Learning-induced changes were seen to have occurred in the posterior hippocampus and the parietal cortex presumably as a result of the exam.

Question 8

Mechelli et al. (2004):

Answer 8

Larger parietal cortex in the brains of people who were bilingual compared to matched monolingual controls.

Question 9

What is functional recovery of the brain after trauma?

Answer 9

1. Following physical injury or trauma, unaffected areas of the brain are often able to adapt and compensate for those areas that are damaged.
2. Healthy brains may take over the functions of those areas that are damaged, destroyed or even missing.
3. Neuroscientists show that this process can occur quickly after trauma (spontaneous recovery) and then slow down after several weeks.
4. They may require rehabilitative therapy to further their recovery.

Question 10

What happens in the brain during recovery?

Answer 10

1. The brain is able to rewire and reorganise itself by forming new synaptic connections close to the area of damage.
2. Secondary neural pathways that would not typically be used to carry out certain function are activated or ‘unmasked’ to enable functioning to continue often in the same way as before (Doidge 2007)

Question 11

Process of functional recovery:

Answer 11

1. Axonal sprouting: The growth of new nerve endings which connect with other undamaged nerve cells to form new neuronal pathways.
2. Reformation of blood vessels.
3. Recruitment of homologous areas on the opposite side of the brain to perform specific tasks. If Broca’s area was damaged on the left side, the right side equivalent would carry out its functions

Question 12

E: Practical Application

Answer 12

1. Understanding the processes involved in plasticity has contributed to the field neurorehabilitation.
2. Following injury of illness to the brain, spontaneous recovery tends to slow down, so after a number of weeks some forms of physical therapy may be required.
3. Techniques may include movement therapy and electrical stimulation of the brain to counter the defecits in motor or cognitive functioning that may be experienced after a stroke.
4. Though the brain has the ability to fix itself to a point, this process requires further intervention.

Question 13

E: Negative Plasticity

Answer 13

1. The brain’s ability to rewire itself can sometimes have maladaptive behavioural consequences.
2. Prolonged drug use for instance has been shown to result in poorer cognitive functioning as well as increased risk of dementia later in life (Medina et al. 2007).
3. 60-80% of amputees have been known to develop phantom limb syndrome- the continued experience of sensations in the missing limb.
4. These sensations are painful and are thought to be due to cortical reorganisation in the somatosensory cortex that occurs as a result of limb loss.
5. (Ramachandran and Hirstein 1998)

Question 14

E: Age and Plasticity

Answer 14

1. Functional plasticity tends to reduce with age, the brain has a greater propensity for reorganisation in childhood as it is constantly adapting.
2. Ladina Bezzola et al. (2012) demonstrated how 40 hours of golf training produced changes in the neural representation of movement in participants aged 40-60.
3. fMRI, showed that researchers observed reduced motor cortex activity in the novice golfers compared to the control group.
4. More efficient neural representations after training.
5. Neural plasticity does continue throughout the lifespan.

Question 15

E: Support from Animal Studies

Answer 15

1. Early evidence was found from animal studies.
2. Pioneering study by David Hubel and Torsten Wiesel (1963) sewed a kitten’s eye shut and analysed the brain’s cortical response.
3. The area of the visual cortex associated with the shut eye was not idle but continued to process information from the open eye.

Question 16

E: The Concept of Cognitive Reserve

Answer 16

1. Evidence shows that a person’s educational attainment may influence how well the brain functionally adapts after injury.
2. Eric Schneider et al. (2014) showed that the more time people with brain injuries spent in education, which was taken as an indication of their ‘cognitive reserve’, the greater their chances of a disability free recovery (DFR)
3. 2/5 of participants studied who achieved DFR had more than 16 years education compared to about 10% of participants who had less than 12 years of education.

Question 17

E: Kuhn et al and Davidson et al.

Answer 17

1. K found a significant increase in grey matter in various regions of the brain after participants played video games foe 30 minutes a day for 30 minutes.
2. D demonstrated the permanent change in the brain generated by prolonged meditation.
3. Buddhist monks who meditated frequently had a much greater activation of gamma waves than students with no experience with meditation.
4. The idea of plasticity and the brain’s ability to adapt.

Question 18

Taijiri et al. (2013):

Answer 18

1. Stem cells provided to rats after brain trauma showed a clear development of neuron-like stem cells in the area of injury.
2. Demonstrates the ability of the brain to create new connections using neurons manufactured by stem cells.

Question 19

E: Elbert et al.

Answer 19

1. Functional recovery can deteriorate with age.
2. The capacity for neural reorganisation is much greater in children than in adults, meaning neural regeneration is less effective in older brains.
3. This may explain why adults find change more demanding than young people.

Question 20

E: Danelli et al.

Answer 20

1. Studied the linguistic profile and neurolinguistic organisation of a 14 year (EB) old who underwent an left hemispherectomy at the age of 2.5 years old. His langauge centres were removed including Broca and Wernicke’s area
2. After the initial aphasia his language skills recovered within 2 years, with the exception of some word finding problems.
3. fMRI patterns suggested that his lone right hemisphere followed a left-like blueprint of the linguistic network.