Neural Plasticity And Functional Recovery

Question 1

What is neural plasticity?

Answer 1

Neural plasticity refers to the brain’s tendencies to change and adapt (functionally and structurally) as a result of experience and learning

Question 2

Explain why the brain is referred to as ‘plastic’?

Answer 2

• synaptic connections are formed and printed during infancy and the brain experiences a rapid growth in synaptic connections peaking at approximately 15,000 at 2-3 years (Gopnik et al, 1999)
• as we age, rarely used ‘connections’ are ‘deleted’ and frequently used ones are strengthened= synaptic pruning
• originally thought such changes restricted to childhood but more recent research suggests that neural connections can change or be formed at any time in life as a result of learning and experience

Question 3

Concept of plasticity supported by what 2 studies?

Answer 3

• Maguire et al’s study of London taxi drivers’ brains

- Draganski et al’s study of medical students’ brains

Question 4

Explain how Maguire at al’s study of London taxi drivers’ brains supports the idea of neural plasticity

Answer 4

• Maguire at al found significantly more volume of grey matter in the posterior hippocampus (part of the brain associated with the development of spatial and navigational skills) than a matched control group- as part of their training, London cabbies must take a complex test called ‘The knowledge’ which assesses their recall of the city streets and possible routes. It appears that thus learning experience alters the structure of the taxi drivers’ brains. Also found that the linger they’d been in the job the more pronounced the structural difference

Question 5

Explain how Draganski et al’s study of medical students’ brains supports neural plasticity

Answer 5

Draganski et al imaged brains of medical students three months before and after their final exams. Learning-induced changes were seen to have occurred in the posterior hippocampus and parietal cortex, presumably as a result of studying for the exam

Question 6

What is functional recovery?

Answer 6

A form of neural plasticity- following damage through trauma, the brain’s ability to redistribute or transfer functions usually performed by a damaged area (s) to other undamaged area (s). Neuroscientists suggest that process can occur quickly after trauma (spontaneous recovery) and then slows down- at which point the person may require rehabilitative therapy

Question 7

What is the main processes involved in functional recovery?

Answer 7

neuronal unmasking

Question 8

What is neuronal unmasking?

Answer 8

• across the brain are dormant synapses
• when an individual is in good health, these synapses are not being utilised (activated) so they remain dormant
• when trauma occurs the brain may need to locate other areas to compensate
• this leads to the brain activating the dormant synapses which can act as a substitute for those which have been damaged

Question 9

How does neuronal unmasking work?

Answer 9

The brain is able to ‘rewire’ and reorganise itself by for,ing new synaptic connections close to the area of damage. Secondary neural pathways, that would normally not be used to carry out certain functions are ‘unmasked’ to ensure particular function isn’t compromised ; this process is supported by a number of structural changes

Question 10

What are 2 further features of neuronal unmasking?

Answer 10

• axon sprouting

- recruitment of homologous areas in the opposite hemisphere

Question 11

What is axon sprouting?

Answer 11

The growth of new nerve cell endings (axon) which connect with other undamaged nerve cells to form the new neuronal pathway

Question 12

What is recruitment of homologous areas in the opposite hemisphere?

Answer 12

Two hemispheres of the brain are largely symmetrical, but as we saw in lateralisation, each side may have its own strengths. However, recruitment of homologous areas involves the functions being recovered by the dormant areas of the opposing hemisphere

Question 13

What are the evaluation points for neural plasticity and functional recovery?

Answer 13

✅ practical applications (neurorehabilitation)
❌ potential consequences of neural plasticity (drug use)
❌ relationship between age and plasticity is complex
✅ support from animal studies of neural plasticity (kittens)
❌ cognitive reserve affects neural plasticity

Question 14

Explain how neurorehabilitation supports neural plasticity

Answer 14

Understanding the processes involved in plasticity has contributed to the field of neurorehabilitation- techniques may include movement therapy and electrical stimulation of the brain to counter the deficits and/or cognitive functions that may be experienced following a stroke, for example. This shows that although the brain may have the capacity to ‘fix’ itself to a point, this process requires further intervention if it is to be successful

Question 15

Explain how negative consequences is a limitation of neural plasticity?

Answer 15

The brain’s ability to ‘rewire’ itself can sometimes have maladaptive behaviour consequences e.g. prolonged drug use has been shown to result in poorer cognitive functioning as well as increasing the risk of dementia (Medina et al). Also, 60-80% of amputees experience phantom limb syndrome (the continued experience of sensations in the missing limb as if it were still there. These sensations are usually unpleasant, painful and are thought to be due to reorganisation in the somatosensory cortex. Such evidence suggests that the structural and physical processes involved in functional recovery may not always be beneficial

Question 16

Explain how the fact that the relationship between age and plasticity is complex is a limitation of neural plasticity

Answer 16

Functional plasticity tends to reduce with age. The brain has a greater prosperity for reorganisation in childhood as it is constantly adapting to new experiences and learning. However, Bezzola et al demonstrated how 40 years of golf training produced changes in the neural representation of movement in participants aged 40-60 showing that neural plasticity does continue through the lifespan. Ultimately though, the relationship is very complex and so cannot always support the idea of neural plasticity

Question 17

Explain how animal studies support neural plasticity

Answer 17

Early evidence of neural plasticity and functional recovery was derived from animal studies. Hubel and Wiesel sewed one eye of a kitten shut and analysed the brain’s cortical responses. It was found that the area of the visual cortex associated with the shut eye was not idle (as had been predicted) but continued to process information from the open eye. This pioneering study demonstrates how a loss of function leads to compensatory activity in the brain = evidence of neural plasticity

Question 18

Explain how cognitive reserve is a limitation of neural plasticity?

Answer 18

Evidence suggests that a person’s education attainment may influence how well the rain functionally adapts after injury. Schneider et al discovered the more time the brain injury patients had spent in education (which was taken as an indication of their cognitive reserve) the greater their chances of a disability-free recovery (DFR)- 2/5ths of patients studied who achieved DFR had more than 16 years education compared to about 10% of patients who had less than 10 years of education. This suggests that cognitive reserve is a crucial factor determining how well the brain adapts after trauma