There is a tendency to think that a human’s growth is linear. A baby is born, it grows up, then becomes an adult. But, the human is body is actually more complex than this. The brain, for example, does not follow a simple formula. It is actually a myth that the brain fully develops during childhood. The prevailing belief is that the brain continues to undergo changes well into adulthood. Neuroplasticity means the brain is malleable and is able to adapt based on various factors.
Neuroplasticity means what exactly?
Neuroplasticity is a combination of two words. “Plasticity” means the ability to be molded, while “neuro” refers to neurons. Neurons are the nerve cells that make up the brain and the nervous system. Also known as brain plasticity, neuroplasticity means the nervous system can change its activities by reorganizing its structure, functions, and connections. There are different factors that can cause this to happen. Some examples are stress, hormones, drugs, environmental stimulation, and age1
Surprisingly, the concept of the brain as an ever-changing thing goes way back. Ernesto Lugaro, an Italian psychiatrist, first introduced the term plasticity in the neurosciences in 1906. He believed that neurons can adapt to learn and recover from damage throughout a person’s life.2
The idea became more widespread when Santiago Ramón y Cajal, nicknamed the “father of neuroscience” coined the term neural plasticity when he described nonpathological changes in adult brains. Although this was not a new idea, it was controversial. Many experts at that time believed that the brain has a certain number of neurons that simply die off and cannot be replaced.3
Today, neuroplasticity is widely accepted and does not just refer solely to the brain, but rather to the entire nervous system.4 It is the basis of some of the most common psychological treatments such as cognitive behavioral therapy.
The types of neuroplasticity
There are two main types of neuroplasticity, and they are categorized based on how they work.
No brain is exactly like another’s. Experiences, genetics, and even somatoform disorders make each one unique. However, there are certain constants in the way the brain works. One of the most glaring is that it is quite active. After a child is born, there are about 2,500 synapses per neuron. By age 3, this grows to 15,000 synapses per neuron.5 An adult, however, has less because of synaptic pruning, which strengthens or eliminates synapses, based on experience. Basically, if neurons are used frequently, they become stronger. If not, they eventually die. These changes are the basis of the concept of neuroplasticity.
Structural Plasticity
The first is structural plasticity, which refers to changes in the brain’s structure due to learning. For example, the effects of adult neurogenesis, or the generation of new neurons, on the hippocampus has been studied. The hippocampus is an area of the brain that is associated with learning, memory, and emotions. Although the extent of adult neurogenesis is still unclear, it is generally accepted that the hippocampus benefits from the production of new neurons throughout a person’s life.6
Functional Plasticity
The other type of neuroplasticity is functional plasticity. It refers to the brain’s ability to use other parts when an area is damaged. I would describe this as the brain’s ability to adapt. Take for example someone who damages their parietal lobe because of a stroke. This can cause numbness in certain parts of the body. With intervention, other parts of the brain can take over the injured areas to restore function.
In his book Neuronal Plasticity: Building a Bridge from the Laboratory to the Clinic, neuropsychologist Jordan Grafman identified four types of functional neuroplasticity. These are homologous area adaptation, cross-modal reassignment, map expansion, and compensatory masquerade.7
Homologous area adaptation happens during the early stages of development. If an area of the brain is damaged in early life, its usual operations can shift to a matching area of the opposite hemisphere of the brain. An example of this is the parietal lobe. The left parietal lobe is associated with the ability to do math, while the right parietal lobe has visuospatial functions. If the right side is damaged, the left can take over and do the job.
Cross-modal assignment happens when the structures that are for a certain kind of input learn to accept new types of sensory inputs. One of the most common examples of this is when blind people have their touch inputs stimulate the visual cortex in the occipital lobe.8
The third kind of functional neuroplasticity is map expansion. Simply put, particular regions of the brain expand or shrink depending on their use. If a person plays an instrument and practices a lot, the “map” or region of the brain that is stimulated expands from repeated use.9
Finally, compensatory masquerade is when the brain uses an alternative way to carry out tasks when the usual ways are impossible because of impairment or injury. In this case, the brain reorganizes preexisting neuronal networks to adapt. An example of this is in memorizing landmarks if an intuitive sense of direction is no longer present.10
Neuroplasticity means there are limits
As promising and useful neuroplasticity is, it is not an all-encompassing phenomenon. It has its limits and only works within the constraints of biology. This means that while the brain is malleable, it is not infinitely so. There are certain parts of the brain that direct particular behaviors. For example, movement, language, and speech all have assigned areas of the brain.
If the key areas of the brain are damaged, some recovery is possible. However, other areas of the brain cannot fully take over the functions that work with the damaged area.11 A good example is that the color-detection brain cells of blind people cannot be used for touch because they are hard-wired for visual input. 12
Another limitation of neuroplasticity is age. There is evidence that neuroplasticity, while still possible, declines as a person gets older because the brain becomes less flexible.13
Conclusion: Neuroplasticity means adaptability towards surroundings
The expression, “you can’t teach an old dog new tricks” turns out to be untrue after all. There is growing evidence that the brain and nervous system’s ability to adapt are lifelong characteristics. Neurons can create new connections to respond to changes in behavior, surroundings, and even injury. When these changes occur, unaffected areas can compensate to recover lost functions. Neuroplasticity happens to everyone, but how effectively depends on factors like age and health.
Neuroplasticity has benefits for interventions after injury or age-related cognitive decline. It can also have benefits to improve mental conditions. The University of Utah has suggested strategies to improve the well-being of a person. The author suggests learning new skills and lists five components to take advantage of neuroplastic change. These are challenge and novelty, intention, specific attention, repetition and intensity, and time. By investing in the learning process, you can take advantage of the brain’s active nature.
Cited Sources
- Fuchs E, Flügge G. Adult neuroplasticity: more than 40 years of research. Neural Plast. 2014;2014:541870. doi: 10.1155/2014/541870. Epub 2014 May 4. PMID: 24883212; PMCID: PMC4026979. ↩︎
- Berlucchi, G. (2002). The Origin of the Term Plasticity in the Neurosciences: Ernesto Lugaro and Chemical Synaptic Transmission. Journal of the History of the Neurosciences, 11(3), 305–309. https://doi.org/10.1076/jhin.11.3.305.10396 ↩︎
- Stahnisch FW, Nitsch R. Santiago Ramón y Cajal’s concept of neuronal plasticity: the ambiguity lives on. Trends Neurosci. 2002 Nov;25(11):589-91. doi: 10.1016/s0166-2236(02)02251-8. PMID: 12392934. ↩︎
- Zilles K. Neuronal plasticity as an adaptive property of the central nervous system. Annals of Anatomy. 1992;174(5):383–391. doi: 10.1016/s0940-9602(11)80255-4. ↩︎
- The University of Maine. Bulletin #4356, Children and brain development: What we know about how children learn. ↩︎
- Leuner B, Gould E. Structural plasticity and hippocampal function. Annu Rev Psychol. 2010;61:111-40, C1-3. doi: 10.1146/annurev.psych.093008.100359. PMID: 19575621; PMCID: PMC3012424. ↩︎
- Grafman, J., Litvan, I. (1999). Evidence for Four Forms of Neuroplasticity. In: Grafman, J., Christen, Y. (eds) Neuronal Plasticity: Building a Bridge from the Laboratory to the Clinic. Research and Perspectives in Neurosciences. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-59897-5_9 ↩︎
- Rugnetta, Michael. “neuroplasticity”. Encyclopedia Britannica, 9 Oct. 2024, https://www.britannica.com/science/neuroplasticity. Accessed 5 November 2024. ↩︎
- Olszewska A., Gaca M., Herman A., Jednoróg K., Marchewka A., How Musical Training Shapes the Adult Brain: Predispositions and Neuroplasticity. (2002) Frontiers in Neuroscience, (15), https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2021.630829 DOI=10.3389/fnins.2021.630829 ↩︎
- Grafman, J. (2000). Conceptualizing functional neuroplasticity. Journal of Communication Disorders, 33 (4), 345–356. https://doi.org/10.1016/s0021-9924(00)00030-7 ↩︎
- Kiran S, Thompson C. Neuroplasticity of language networks in aphasia: Advances, updates, and future challenges. Front Neurol. 2019;10:295. doi:10.3389/fneur.2019.00295 ↩︎
- Grafman, J. (2000). Conceptualizing functional neuroplasticity. Journal of Communication Disorders, 33 (4), 345–356. https://doi.org/10.1016/s0021-9924(00)00030-7 ↩︎
- Lu, T., Pan, Y., Kao, S.-Y., Li, C., Kohane, I., Chan, J., & Yankner, B. A. (2004). Gene regulation and DNA damage in the ageing human brain. Nature, 429 (6994), 883–891. https://doi.org/10.1038/nature02661 ↩︎