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Plasticity and Functional Recovery of the Brain After Trauma

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Plasticity and Functional Recovery of the Brain After Trauma

The brain is not a rigid organ. Adaptation to new experiences is one of its fundamental functions. Plasticity is the brain’s ability to change and adapt to the environment, both in function and structure. This can result from multiple experiences, such as needing to learn a new skill or language, or due to developmental changes, such as growing from infancy to adulthood. Therefore, plasticity and functional recovery of the brain after trauma are heavily connected.

Plasticity is crucial to the brain’s response to trauma.

Plasticity and Functional Recovery of the Brain After Trauma The Brain plasticity and function StudySmarterThe brain with labelled lobes, Cancer Research UK via Wikimedia Commons.

How plasticity in the brain works

The brain contains billions of neurones the likes of which are connected by synapses. Information travels between neurones, and each piece of new information creates new neuronal pathways.

Plasticicty and Functional Recovery of the Brain After Trauma Neurons brain StudySmarterNeurones in the brain, Tyler Smith - StudySmarter Originals.

By revising and repeating information through reading or practising a certain activity, the pathways become stronger. When we don’t repeat or practise a piece of information for a while, it becomes weaker, and in some cases, it is removed altogether. This is known as synaptic pruning.

Synaptic pruning increases the brain’s levels of efficiency, especially as a communication system. This means fewer connections overall, but the remaining connections are stronger. Demarin and Morović (2014) describe pruning as the process of ‘use it or lose it.

This process is more active in those who are younger. Newborns and children will constantly undergo this pruning process and will have more neurones and neuronal pathways than a young adult, and a young adult will have more than an adult. This doesn’t mean that adults are incapable of utilising the brain’s plasticity.

Elbert et al. (1995) found that the process of neural reorganisation is more efficient in children than that in adults, which suggests a few things about ageing and the brain. Namely, older brains seem to be less effective than younger brains when attempting functional recovery.

Elbert et al’s (1995) study is key, as is Kuhn and Gallinat’s (2014), so try to remember these ones in particular!

Kuhn and Gallinat (2014) scanned 62 adult male brains using an MRI (magnetic resonance imaging). They then compared the images to find a correlation between grey matter volume (GM) and the lifetime amount of video gaming.

There was a significant positive correlation between GM and the left occipital cortex, inferior parietal lobe, hippocampus, and entorhinal cortex.

The entorhinal cortex volume could be predicted by the genre of games a man played. So, if a person played logic or puzzle games it contributed positively to the correlation, and action-based role-playing games contributed negatively.

These video game years were also positively correlated with hippocampus volume!

This could potentially allude to the neural plasticity in navigation and visual attention areas of function.

The brain can also form new connections with neuronal cell bodies forming additional branches and axons. This process is known as axonal sprouting. This is a form of plasticity similar to neural regeneration: when an area of the brain is damaged, new neurones and connections are generated. Overall, this affects the structure of the brain and can appear in scans such as MRIs.

There’s evidence to say that taking certain addictive drugs for some time causes structural plasticity changes. This was demonstrated by Kolb and Robinson (2004). They found that addictive substances such as nicotine and morphine cause changes in the structure of dendrites and dendritic spines in brain regions such as the nucleus accumbens and the prefrontal cortex.

What is functional recovery after trauma in the brain?

Functional recovery is possible in the brain. Let’s see some examples.

Trauma to the brain can happen in one of two ways:

  1. Direct: damage occurs due to being hit in some form in the head (for instance, if someone were to fall over and bang their head).

  2. Indirect: damage occurs due to swelling, bleeding (for instance, if someone has a stroke), or oxygen deprivation to brain regions.

When there is a loss of axons in a pathway due to direct or indirect trauma, the remaining axons become more sensitive as a result. This means they are more likely to ‘fire’.

This is known as denervation supersensitivity.

  • Baranauskas and Nistri (1998) found that consistent, intense, or noxious (painful or harmful) stimuli to neurones will cause sensitisation. They described it as one of the fundamental forms of synaptic plasticity.

    • Nociceptors are types of neurones, usually found in the skin, that are responsible for detecting extremes in temperature and pressure and injury-related chemicals.

    • In the spinal cord, repeated stimulation of the dorsal roots, including nociceptive nerve fibres, can cause progressive increases in the number of action potentials (the nerve ‘firing’, in a sense) generated by motoneurones and interneurones found there.

    • This consistent firing increases the sensitivity of these neurones, and, ultimately, increases the spines sensitivity to pain.

  • Cannon and Rosenblueth (1949) demonstrated the ‘law of denervation,’ which states that surgical denervation causes supersensitivity in neurones. The closer the neurones are to the damaged areas/cut neurones, the greater the supersensitivity. This decreases the chain of neurones.

Plasticity and Functional Recovery of the Brain After Trauma Denervation Supersensitivity plasticity StudySmarterNeurones damaged resulting in sensitivity, Tyler Smith - StudySmarter Originals.

Functional recovery: healthy areas compensate for damaged areas

We define functional recovery of the brain as the brain’s ability to regain functions lost through trauma. After the brain is damaged, for instance, if a person slips and bangs their head in an accident, healthy areas of the brain compensate for the damaged areas. This is what functional recovery essentially means. This can occur through neuronal unmasking, or through stem cells (research is still being conducted on this.)

This process overall is known as functional reorganisation.

Certain areas of the brain have been damaged or lost due to the incident, so the function associated with that portion of the brain is affected or lost. Therefore, healthy portions of the brain undergo functional reorganisation to regain the ability to do the function that has been lost.

Neuronal unmasking may occur. Areas close to the damaged portions of the brain that have dormant synapses (synapses that haven’t received enough input to be active), open connections to compensate for the damaged areas.

See the study conducted by Wall et al. (1977), where they found a large number of nerve terminals weren’t doing much at all. This was the case when normal functions were occurring in a healthy brain. However, when afferent nerve fibres (basically, when nerves were conducting inwards or were nearby to other nerves in an interconnected way) were damaged or blocked, those dormant nerves activated. This is an alternative to sprouting, in a sense, and explains plasticity in adult brains.

Functional recovery is affected by:

  1. Age: children, particularly newborns, have the best ability to recover, more so than young adults and adults. There is a negative correlation.

  2. Gender: women can recover more from brain damage than men.

  3. Therapy: rehabilitative therapy increases the ability to recover a function. For example, if there is paralysis in a limb after a head injury, in therapy they would focus on the paralysed limb to help it recover.
  4. Education: those who had a higher level of education were more likely to have a speedier recovery from brain injuries.

Rehabilitative therapy

Rehabilitative therapy can be used in the form of constraint-induced therapy. This is where patients are prevented from using coping strategies and are effectively forced to use the affected area of lost function.

If a person has lost the ability to use speech, for instance, and rely on body language to communicate, they will be encouraged to speak in any form possible, to encourage the brain to functionally recover and other brain regions compensate to regain function. If they have lost dexterity in one hand, they will be constrained so they have to use the affected hand.

The function is transferred through neural reorganisation.

Evaluation of the plasticity and functional recovery of the brain after trauma

Let’s discuss the validity of the studies on plasticity and functional recovery of the brain.

  • Maquire et al. (2000) studied a group of 16 male taxi drivers, comparing them to a control group. Taxi drivers in London have to undergo a test called ‘The Knowledge’ to prove they can remember the vast amounts of streets and routes in London.

    • ‘The Knowledge’ is incredibly extensive and requires up to two years of studying.

    • The study required taxi drivers to have been working for at least 1.5 years.

    • Researchers found that the posterior hippocampus, responsible for spatial memory in the form of navigation, was significantly larger in the taxi drivers. It was also positively correlated with the time spent working as a taxi driver.

    • This suggests the physical structure of the brain can change depending on the environment and the experiences of the individual. The brain can reconfigure itself and essentially adapt to the psychological demands of improved memory formation.

  • Danelli et al. assessed a 14-year-old patient, known as EB. EB was born with a tumour in their brain, and at the age of two, they were given a hemispherectomy (removal) of the left side of their brain.

    • This removed important, well-known areas of the brain: Broca’s area, and Wernicke’s area, the language centres.

    • EB lost nearly all of their language capabilities after surgery, however, after two or so years, they regained nearly full use of their language abilities.

    • EB developed normally, with a few issues (dyslexia.)

    • Researchers found in the fMRI images of EB’s brain, that the right hemisphere had adapted and changed structurally, to the point of ‘matching’ a similar structure that language centres lost in the left hemisphere would have had.

    • This suggests the brain can recover after significant damage or injury. The right hemisphere adopts roles normally taken by the left, performing them almost optimally.

  • Overall, the results of this study help those in rehabilitative therapies. Physiotherapists can confidently use focused therapy styles to help people return to normal lifestyles.

  • This study gives us a deeper understanding of the nuances of the brain. Such a complex organ requires extensive research, and this research is constantly being assessed and updated.

Phineas P. Gage

A famous case study is that of Phineas P. Gage. In 1848, he was working on a railway, packing explosives into the ground with an iron bar.

Plasticity and Functional Recovery of the Brain After Trauma Phineas P. Gage StudySmarterA portrait of Phineas P. Gage after his injury, Wikimedia Commons.

The explosives went off, and the bar went through his skull and through his left frontal lobe. At first, Gage could walk and talk. Then, he collapsed and his health deteriorated over the next few days, where he was in and out of a coma.

After 24 days Gage was effectively back to normal. However, he had memory loss and anger issues after the injury (something his friends noted). He lived for 12 more years.

Phineas Gage is a great example of plasticity and functional recovery in action. He lost portions of his brain, received a significant injury to the remaining portions close by, and still was able to almost fully recover despite the loss.

Plasticity and Functional Recovery of the Brain After Trauma - Key takeaways

  • Plasticity is the brain’s ability to change and adapt to the environment, both in function and structure.
  • The brains neurones, connected by neuronal pathways, become stronger by revising and repeating information.
  • Synaptic pruning is when neuronal pathways are weakened or removed altogether due to lack of use/repetition. Axonal sprouting is where new connections form, with neuronal cell bodies forming additional branches and axons.
  • Trauma to the brain can occur directly or indirectly, and functional recovery allows for healthy, remaining areas of the brain to compensate. This can happen even in cases of extreme injury.
  • Therapies, age, and gender are factors in functional recovery. Constraint therapy is an example of the rehabilitative therapies available. Younger people have better chances of synaptic recovery than older people, and women have more chances of recovery than men.
  • Structural changes can be seen in many cases supported by research. Phineas P. Gage is one of the most influential examples.

Frequently Asked Questions about Plasticity and Functional Recovery of the Brain After Trauma

Functional recovery is when the functions of damaged areas of the brain are transferred to other, undamaged areas of the brain.

Depending on the severity of the damage, the brain will either completely transfer/rewire its functions to healthier areas or repair the area to the best of its ability.

Functional plasticity refers to the brain’s ability to transfer functions of one area of the brain to another, following trauma/damage.

Final Plasticity and Functional Recovery of the Brain After Trauma Quiz

Question

What is plasticity in the brain?

Show answer

Answer

Plasticity is the brain’s ability to change and adapt to the environment, both in function and structure.

Show question

Question

What is synaptic pruning? 


Show answer

Answer

Synaptic pruning is when neuronal pathways are weakened or removed altogether due to lack of use/repetition. 


Show question

Question

What does synaptic pruning achieve? 


Show answer

Answer

It improves the brains communication efficiency, as it removes unnecessary or weakened pathways, but the ones remaining are stronger. 


Show question

Question

What is axonal sprouting? 


Show answer

Answer

This is when new connections form, with neuronal cell bodies forming additional branches and axons. 


Show question

Question

What did Kolb and Robinson (2004) find in their study?

Show answer

Answer

They found that addictive substances such as nicotine and morphine cause changes in the structure of dendrites and dendritic spines in brain regions, such as the nucleus accumbens and the prefrontal cortex. 


Show question

Question

What is neural regeneration?

Show answer

Answer

This is when new neurones and connections generate after an area of the brain is damaged. 


Show question

Question

What are the two types of trauma that can occur to the brain? 

Show answer

Answer

Direct and indirect. 


Show question

Question

What is denervation supersensitivity?

Show answer

Answer

When there is a loss of axons in a pathway, possibly from a result of direct or indirect trauma, the remaining axons become more sensitive as a result.

Show question

Question

What did Cannon and Rosenblueth (1949) find in their study? What term did they create? 


Show answer

Answer

They created the term ‘law of denervation.’ In their study, they found that surgical denervation causes supersensitivity in neurones. The closer the neurones are to the damaged areas/cut neurones, the greater the supersensitivity. This decreases the chain of neurones.

Show question

Question

What is functional reorganisation?

Show answer

Answer

Where injury has occurred, healthy portions of the brain undergo functional reorganisation to regain the ability to do the function that has been lost. Functions lost are ‘picked up’ by unassociated areas of the brain, to regain function. 


Show question

Question

What is neuronal unmasking? 


Show answer

Answer

This is where areas close to the damaged portions of the brain that have dormant synapses (synapses that haven’t received enough input to be active), open connections to compensate for the damaged areas. 


Show question

Question

What are the three factors affecting functional recovery? 


Show answer

Answer

Age, gender, and rehabilitative therapy.

Show question

Question

What did Maquire et al. (2000) find in their study?

Show answer

Answer

When comparing taxi drivers who had undergone ‘The Knowledge’ test in London to a control group, taxi drivers had significantly larger posterior hippocampus’s, positively correlated with their time spent as taxi drivers. This suggests the physical structure of the brain can change depending on the environment and the experiences of the individual.

Show question

Question

What did Danelli et al. (2013) find in their study? 


Show answer

Answer

When EB (a 14-year-old) had a tumour removed as an infant, through a left hemispherectomy (removing Broca’s and Wernicke’s areas, language centres of the brain), the child developed normally despite this significant trauma to the brain, with only a few language issues (dyslexia). The right hemisphere adapted to compensate for the missing brain functions. 

Show question

Question

What is the case of Phineas P. Gage?

Show answer

Answer

A man working on a railway in 1848 received significant brain injury when an iron bar went through his left frontal lobe. He deteriorated before making an almost complete recovery 24 days later, with only a few issues with memory loss and temper control as a result. He lived for 12 more years.


Show question

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