Introduction
Brain plasticity, also referred to as neuroplasticity or neural plasticity, has been researched for many decades and various discoveries have led to the development of effective methods and strategies to treat numerous disorders. Interest in this phenomenon was sparked at the end of the 19th century and scientists promoted the idea that people’s brains were adaptable in a certain way (Denes 2015).
At the time, the idea was rather revolutionary, as it was supposed that the morphology of the brain was static. Modern researchers have explored the concept and come up with new strategies to treat numerous conditions that have adverse effects on the quality of patients’ lives. Although new evidence of neuroplasticity appears regularly, some sceptics still doubt it exists beyond certain stages of mammalian development. This paper examines some of the recent findings that demonstrate the healing power of the brain known as brain plasticity.
Defining Neuroplasticity
When defining the phenomenon, scientists address several aspects, including the concepts of change and people’s age, environment, learning, and behaviour, among others. Neural plasticity can be defined as “the capacity of neurons and of neural circuits in the brain to change, structurally and functionally, in response to experience” (Sale, Berardi & Maffei 2014, p. 190). In more specific terms, neuroplasticity is the ability of the nervous system to change the anatomy and organisation of structures and their functions due to experience, injury, or learning (Cai et al. 2014).
Merzenich, Van Vleet, and Nahum (2014) stress that researchers used to see neuroplasticity as a process that could take place in the prenatal and early childhood periods only. Many studies conducted in the 20th century and more recent findings suggest that the brain can remain plastic to any age. Cai et al. (2014, p. 2), for instance, define brain plasticity as “an inherent characteristic or ability for lifelong skills learning and relearning”. The researchers emphasise that the adaptability of the brain does not depend on people’s age, although its peak is still during the prenatal and early childhood periods.
Stem Cells and Neural Plasticity
As mentioned above, the first major steps toward an understanding of brain plasticity were made in the 19th century. William James is seen as one of the central figures in this process, although he was not the first researcher to explore this phenomenon. However, his input into the development of the theory based on the capacity of the nervous system can hardly be overestimated (Denes 2015). James emphasised that brain plasticity involved the emergence of new neural components and new brain paths. These assumptions and the theory built on them became the basis of ensuing research that enabled scientists to dig deeper into the nature of neuroplasticity.
The development of new neural components, and thus brain plasticity, is supported by recent findings involving the functioning of stem cells. It was believed that these cells evolve exclusively during embryonic development. One of the most remarkable properties of neural cells is their capacity to evolve into different types of cells (Denes 2015). These new neural components integrate into networks that already exist, making brain adaptability possible.
The idea of stem cells’ ability to be differentiated dates back to 1893, when August Weismann identified two types of cells in the process of embryogenesis, germ and somatic cells (Sánchez Alvarado & Yamanaka, 2014). These early theories were later crystallised into theories based on the notion of cells’ reprogramming. Researchers conducted numerous experiments involving various species and found that stem cells could be reprogrammed if the environment changed. Chemical, physical, or thermal stress could boost cells’ reprogramming process.
The exploration of stem cells in the human body led to the development of cell therapies that involve the introduction of stem cells into the injured tissue. The results are more than promising, since such treatment has proved to be effective with patients diagnosed with Parkinson’s and Alzheimer’s diseases or those who had spinal cord injuries, and many other serious health issues (Sánchez Alvarado & Yamanaka 2014; Copland & Angwin 2014; Hampstead & Sathian 2014). Stem cells integrate into existing neural networks and perform the functions of the cells that have been damaged.
Injury and Neuroplasticity
The brain’s capacity to adapt in response to different kinds of injuries can be regarded as solid evidence for the existence of such phenomena as neural plasticity. As mentioned above, it was accepted that each area of the brain had various functions, and that damage to any part of the central nervous system led to the loss of certain abilities (Denes 2015). However, this assumption was questioned, as many people could recover some functions, even though their brains had been severely damaged. For instance, post-stroke patients or those whose brains have been injured often learn how to see, walk, and speak again, although the corresponding areas of the brain do not function properly (Nadeau 2014).
Scientists explain that the central nervous system is able to produce new neural cells and synapses, which ensures continuous learning. Cases where patients had a part of their brain removed and still regained an ability to perform some tasks illustrate the way brain plasticity works.
Modern scientists have used these findings to develop pharmacological and nonpharmacological therapies to address various disorders and other health issues. For example, noradrenergic agonists are utilised to improve M1 excitability (Di Pino et al. 2014). Training and simulations are common nonpharmacological therapies that have proved to be effective in motor learning and treating cognitive impairments (Cai et al. 2014). It is noteworthy that the balance between training and sleep is instrumental in achieving significant progress when addressing the issues post-stroke patients have to face. People’s exposure to new environments also leads to a change in the morphology of the brain.
Phantom Limbs and Brain Plasticity
Additional evidence of brain plasticity is provided by researchers investigating phantom limbs. It is necessary to note that this phenomenon is associated with both positive and negative effects on people’s quality of life. As an example of an adverse influence of neuroplasticity on the lives of people with amputated limbs, up to 85% of these people report feeling phantom limb pain (Kuffler 2017). Substantial research in this area suggests that phantom sensations are an outcome of maladaptive brain plasticity. The origin of this phenomenon is linked to the functioning of the somatosensory neural network and brain’s misinterpretation of activity among the network’s components (Denes 2015).
Experimental evidence for this assumption has been provided since the 1990s. In one of the studies on the nature of phantom limb pain, participants reported the disappearance of phantom sensations following a cerebral lesion associated with the representation of the amputated limb (Denes 2015). The use of magnetoencephalography (MEG) also sheds light on the origin of the phenomenon, as recorded somatosensory maps show that certain brain areas could be activated when touching a limb above the amputation line.
Chronic pain can be regarded as a phenomenon similar to phantom limb pain. When tissue is damaged, stimuli sent from the periphery to the central nervous system lead to morphological changes in the brain and somatotopic reorganisation (Denes 2015). Chronic pain is found to lead to the reduction of grey matter volume, but this effect is reversible when the pain is eliminated (Ray 2014). Hence, chronic pain and its impact on people’s health can be regarded as evidence for brain plasticity.
Apart from phantom pain, neuroplasticity can be associated with positive influences on the lives of people whose limbs are missing. Tyler (2015) stresses that patients with prosthetic limbs report significant improvements with the use of their prostheses.
The stimulation of certain areas activates somatosensory perception of the missing limb. Patients start feeling their phantom limbs, which improves the quality of their lives as they manage to use prostheses more effectively. Some people found it just as important to feel when their loved ones touched their phantom hand (Tyler 2015). Importantly, therapy involving stimulation also led to the complete elimination of phantom limb pain. Therefore, a phenomenon that is often regarded as maladaptive plasticity can be properly managed.
Conclusion
To sum up, it is possible to state that the notion of neuroplasticity has been researched for decades and many discoveries in this area have led to the improvement of people’s health conditions. An understanding of the nature of this phenomenon has enabled scientists and practitioners to develop therapies that are effective in treating various disorders that used to be seen as incurable. Research related to stem cells, phantom limbs, chronic pain, and stroke recovery has provided many insights into this phenomenon.
Today it is widely accepted that the human brain can adapt effectively to new environments, and this capacity can and should be utilised properly. Brain plasticity is the key to people’s recoveries from injuries of various types. Neural plasticity is also instrumental in managing health issues associated with aging, which is specifically relevant for many countries whose populations are aging rapidly.
Reference List
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