Basics of neuroplasticity
– “Neuroplasticity is defined as the ability of the nervous system to change its activity in response to intrinsic or extrinsic stimuli by reorganizing its structures, functions or connections.” There is a complete mechanism behind the gradual learning process in an average human. The fact that a newborn has almost nil learning compared to a fully grown-up person is because of the process between the neurons in the brain. Neurons possess the ability to make and change connections or rewire themselves to learn new things. While a computer is considered to be a super machine that is capable of multitasking, on the other hand, a human brain even overpowers these incredible machines with their ability to change themselves by the external stimulus.
This external stimulus comes through the five sensory organs Touch, sight, smell, hearing, and taste. Like an engineer knows the techniques required to repair a damaged computer, a neuroscientist knows the process of rewiring the human brain to ensure that it repairs itself. This entire rewiring process, changing, learning, and improving itself, is termed Neuroplasticity or Brain plasticity.
While talking about the process involving plastic or the induced changes to the brain, knowing about developmental plasticity is essential to eradicate any chances of unwanted confusion. During the growth process of an individual, the brain’s neurons from branches tend to unite with the others to form synapses. The life of these synapses depends on the kind of stimulus that the individual gets from outside. Such stimulus also includes the emotions felt by the individual. The ones that receive the required stimulus stay intact and strengthen with time while the others weaken and finally getaway.
There are various types of neuroplasticity, which we’ll learn in the next topic. Let’s proceed to the next segment of neuroplasticity.
Five Types of Neuroplasticity
- Cortical neuroplasticity:
At birth, each neuron located in the cerebral cortex has around 2500 synapses. As the infant grows, the number of synapses increases up to 15000 per neuron, which is almost twice that of the adult brain. The connections which have been reinforced by sensory stimulation become stronger. Thus, efficient pathways of neural connections are developed. During early childhood, it is crucial for the nervous system to receive sensory inputs for healthy development. The entire process of the drop in the number of connections that are maintained, and the ones that remain because they have been strengthened by sensory experiences, takes place during adolescence.
- Homologous area adaptation:
The life of a human is full of unexpected events, including injuries. The human brain can make sure it compensates for every damage under its control. Homologous area adaption is one such mechanism. Let’s say that the part of the brain that controls the movements of the right arm gets damaged in the early years of life, and the brain makes sure that the other part of it manages to make room for the damaged part, which is referred to as the homologous area adaption.
- Compensatory masquerade:
The easiest way to understand this type of neuroplasticity is that the brain always has a plan B for itself after the initial plan fails. An example to understand the process of compensatory masquerade is an average individual’s capability to remember the navigation while traveling towards a certain destination. Most humans move with the intuitive power they possess for navigation. Still, those who have suffered some injury or have faced mental health issues tend to work with plan B. The consciousness in such people plays a vital role. They tend to adapt to other means, including memorizing the landmarks or other options.
- Cross-modal reassignment:
This is the adaptive reorganization of neurons to integrate the function of two or more sensory systems. This type of neuroplasticity introduces new inputs into a brain area that has been deprived of its main inputs. It usually occurs after sensory deprivation due to disease or brain damage. The reorganization of the neural network is greatest following chronic sensory deprivation, like congenital blindness or prelingual blindness. In these cases, cross-modal plasticity strengthens other sensory systems to compensate for the lack of vision or hearing. This strengthening occurs because of the new connections that are formed to brain cortices.
- Map expansion
The last type of neuroplasticity ensures the flexibility of local brain regions which have been designated to perform one particular function or store specific information. The arrangement of these local regions in the cerebral cortex is depicted as a ‘map’. When a particular function is carried off frequently by repeated behavior, the region of the cortical map involved in that function grows and shrinks while the individual performs the function. This phenomenon is most likely to occur during learning a particular skill.
“Map expansion neuroplasticity has also been observed in association with pain in the phenomenon of phantom limb syndrome. The relationship between cortical reorganization and phantom limb pain was discovered in the 1990s in arm amputees. Later studies indicated that in amputees who experience phantom limb pain, the mouth brain map shifts to take over the adjacent area of the arm and hindbrain maps.”
Now as we are familiar with the various types of neuroplasticity, we are prepared to learn about the mechanisms possessed by it. Following are the mechanisms of neuroplasticity:
Mechanisms of neuroplasticity
- Neuronal Regeneration/Collateral Sprouting
Neuro regeneration involves the synthesis of new neurons and connections, providing extra resources in the long run to replace those damaged by the injury and achieving lasting functional recovery. Plasticity ensures quick recovery of lost abilities in the short or medium term. By understanding the factors that lay in neuro regeneration and plasticity, their advantages can be combined to develop rehabilitation training methods, which contribute to a treatment plan to achieve functional recovery from nervous system injuries. Abilities lost due to brain injury like speech can also be recovered via this method.
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- Functional reorganization
Loss of somatosensory drive results in functional reorganization of the primary somatosensory cortex. The phenomenon of functional reorganization has been well established, yet it is unknown to science whether, in humans, functional reorganization takes place due to the changes occurring in brain anatomy or does it simply reflect an unmasking of existing dormant synapses. Functional magnetic resonance imaging allows a study of the human brain and suggests the relevant functional changes in cerebral networks, after a stroke.
Conclusion:
When a human brain suffers accidental damage, neuroplasticity is the process that takes place to let it regain the maximum working capability it can. A baby while growing up learns through visual and tactile stimuli. Similarly, the brain of the person who suffered from a stroke regains strength by using various tactile stimulations, which include music therapy, virtual environments, and stimulus that tends to bring happiness and compassion in the individual. According to Paraskevopoulos et al., 2012; Kuchenbuch et al., 2014, music is a form of multisensory input that not only requires integration of audiovisual integration but also an appreciation of abstract rules. None of this can occur without neuroplasticity.