"The ability of neurons and neural networks in  the brain  to change their connections and behavior in response to new information, damage, sensory stimulation, development, and dysfunction" (Rugnetta, 2022)

Some brain areas demonstrate modularity through carrying out specific functions while retaining the ability to deviate from these functions and reorganize. Neuroplasticity is multifaceted and allows neurons in the brain to compensate for injuries and disease. The brain may "readjust" activities in response to new situations and changes in their environment. Through developmental plasticity, the brain processes sensory information and may be strengthened or weakened. When unused neural synapses that are permanently removed, we call it pruning, which may unfortunately leave behind sufficient networks. Evidently, neuroplasticity works successfully  through reinforcement of sensory information with experiences in learning and memory. The reinforcement of these experiences stimulate physical reorganization and shifting of the brain. Reinforcement of these neural networks may result pejoratively in physical damage to the brain, sometimes caused by stroke, where the brain must compensate for lost activity. Neurogenesis, the process where new neurons form in the brain, has encouraged further stem cell research in the stroke recovery realm. Enhancement of neurogenesis in those who suffer from Alzheimer's, Parkinson's, strokes, or depression is vital for effective treatment. 

Types of Cortical Neuroplasticity

1. Developmental plasticity

• Occurs primarily within the first few years of life where neurons grow rapidly and create connections. 

"In the first few years of life, more than 1 million new neural connections form every second" 

• Neural connections are "fine-tuned" through interactions with the environment 

• Massive pruning back of excess synapses occurs during adolescence

2. Functional plasticity   

• Brain's ability to move functions from a damaged area after trauma to other undamaged areas

• After a stroke or brain accident, the unaffected brain regions adapt and take over functions of the affected parts 

• Plasticity can enable those with brain damage to regain some past capabilities through rehabilitation 

Ways in which brain plasticity can enable brain-damaged people to regain some of their past capacities

A. Axonal Sprouting 

• Where undamaged axons grow new nerve endings to reconnect the neurons, whose links were severed through damage

• Undamaged axons also sprout nerve endings and connect with other undamaged nerve cells, thus making new links and new neural pathways to accomplish what was once a damaged function

B. Homologous Area Adaptation 

•  Brain behavior becomes active in the equivalent part on the opposite side of the brain from where it usually occurs. If it normally occurs on the right side, then it would instead move to the left side, and vice versa

• If one brain hemisphere is damaged, the intact hemisphere can sometimes take over some of the functions of the damaged one

• Occurs more often in children than in adults

• Moving a module to the opposite side displaces some of the functionality that was originally there and as a result, the two functions may become less effective, contaminating each other

C. Cross-Modal Reassignment 

• When the brain uses an area that would normally process one type of sensory information like sight for a different type of sensory information, like sound

• When a brain region does not receive sensory data as expected, for example when a person has become blind, this brain region may become re used for another sense, like touch

• This can enable blind people to “see” Braille text with their fingers

  • Blind people can learn to reuse their visual centers for hearing, becoming capable of “echolocation” to navigate around environments

D. Map Expansion 

• When the brain notices that a certain area gets extensive use, so it expands this area

• When a person completes an activity or experience, this produces enlargement of the associated brain region. The brain growth occurs right away, so that neuroscientists can detect it through brain imaging technologies in-real time

E. Compensatory Masquerade

• When the brain reuses a component to conduct a mental operation other than what it normally does

• For example, if a person suffers a brain injury, with some functionality lost, then this person may be able to reuse a different method, like finding one’s way by remembered directions instead of by sense of location

3. Structural plasticity

• Brain's ability to change its physical structure as a result of learning

• Changes from memories or experiences

•  Studies the effect of internal or external stimuli on the brain's anatomical reorganization

• For example, changes of grey matter proportion or the synaptic strength in the brain