Neuroplasticity refers to the brain's ability to change and adapt in structure and function in response to learning and experience. It occurs throughout life as new neural pathways are strengthened through learning and experience, while unused pathways weaken and die. Theories of neuroplasticity were first proposed in the late 19th century, and it is now understood that the brain can rearrange its structure and functions through various mechanisms like functional and structural plasticity. Physiotherapy techniques can enhance neuroplasticity and aid recovery after brain damage.

1. Neuroplasticity

3. • Other names – Neural plasticity
- Brain plasticity
• Plasticity is the ability of any structure weak enough to change by an external
stimulus, however strong enough not to mould at a once.
• Neuroplasticity is the capacity of the brain to change and adapt in structure
and function in response to learning and experience. It is the biological,
chemical, and physical capacity for the brain to reorganize its structure and
function.
• This occurs in all healthy people, especially children, as well as after various
problems like brain injuries and stroke. It occurs as a result of learning,
experience and memory formation, or as a result of damage to the brain.
• Learning and new experiences cause new neural pathways to strengthen
whereas neural pathways which are used infrequently become weak and
eventually die. This process is called synaptic pruning.
• Fundamentally, the nervous system needs to rearrange itself in order to adapt
to the unfolding situation that it faces. The genes program the body to have
neuroplasticity so that animals can survive in unpredictable environments.

4. Theories
• The term plasticity was first used in 1890 by William James in The
Principles of Psychology.
• The first person to use the term neural plasticity appears to have been the
Polish neuroscientist Jerzy Konorski.
• Early experimental work on neuroplasticity was conducted by an
eighteenth-century Italian scientist, Michele Malacarne, who discovered
that animals made to learn tasks would develop larger brain structures.
• In the twentieth century, influential neuroscientist Santiago Ramón y Cajal
proposed that neurons in adults break down and rebuild.
• Scientists now think that neuroplasticity occurs throughout all life stages,
having extensive capacities from childhood development through healing
diseases. The brain can rearrange itself in terms of the functions it carries
out, as well as in terms of the basic underlying structure.

5. Dependency factors
The core of this phenomenon is based upon synapses and how connections
between them change based on neuron functioning.
• synapse regulation via phosphorylation
• the role of inflammation and inflammatory cytokines
• proteins such as Bcl-2 proteins and neutrophorins
• energy production via mitochondria

7. Functional Plasticity
• Functional plasticity is the brain's ability to move functions from a
damaged area of the brain after trauma, to other undamaged areas.
Existing neural pathways that are inactive or used for other purposes take
over and carry out functions lost because of the injury.
• After brain injury such as accidents or stroke, the unaffected brain areas
can adapt and take over the functions of the affected parts. This process
vary in speed but it can be fast in the first few weeks (phase of
spontaneous recovery) then it becomes slower.
• It can be helped by rehabilitation, and the nature of rehabilitation
programmes varies with the type of injury from retraining some types of
movement to speech therapy.

8. Axonal sprouting
• Functional plasticity can occur through a process termed axonal sprouting,
where undamaged axons grow new nerve endings to reconnect the
neurons, whose links were severed through damage.
• Undamaged axons can also sprout nerve endings and connect with other
undamaged nerve cells, thus making new links and new neural pathways
to accomplish what was a damaged function.

9. Homologous Area Adaptation
• Although each brain hemisphere has its own functions, if one brain
hemisphere is damaged, the intact hemisphere can sometimes take over
some of the functions of the damaged one.
• In 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.
• This functional neuroplasticity occurs more often in children than in
adults. Shifting over a module to the opposite side displaces some of the
functionality that was originally there.
• As a result, the two functions may become less effective, contaminating
each other.

10. Cross-Modal Reassignment
• Cross-modal reassignment occurs when the brain uses an area that would
normally process a certain type of sensory information (such as sight) for a
different type of sensory information instead (such as sound).
• When a brain region does not receive sensory data as expected, say
because a person has become blind, this brain region may become
repurposed for another sense, like touch.
• This can enable blind people to “see” Braille text with their fingers.
• Also, some blind people learn to reuse their visual centers for hearing
sounds, thus becoming capable of “echolocation” to navigate around
environments.

11. Map Expansion
• In map expansion, the brain notices that a certain area gets extensive use,
so it expands this area . This is comparable to how the body can notice
that certain muscles get more use (such as those involved in an often-
played sport), then grows those muscles larger.
• When a person often engages in 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 while it occurs .

12. Compensatory Masquerade
• Compensatory masquerade involves the brain reusing a component to
conduct a mental operation other than what it would typically do.
• For example, if a person suffers a brain injury, with some functionality lost,
then this person may be able to reuse a different method behind-the-
scenes, like finding one’s way by remembered directions instead of by
sense of location.

13. Neuronal Unmasking
• Wall (1977) noticed the brain contained ‘dormant synapses’ – neural
connections which have no function.
• However, when brain damage occurs these synapses can become
activated and open up connections to regions of the brain that are not
normally active and take over the neural function that has been lost as a
result of damage.

14. Structural Plasticity
• Structural neuroplasticity is the brain's ability to change its physical
structure as a result of learning, involving reshaping individual neurons
(nerve cells).
• During infancy, the brain experiences rapid growth in the number
of synaptic connections. As each neuron matures, it sends out multiple
branches, this increases the number of synaptic contacts from neuron to
neuron.
• As we mature the connections we do not use are deleted and the ones we
use frequently are strengthened, and this is called neural pruning. This
process continues throughout our life.

15. How does neuroplasticity work ?
• At the most basic level, it starts with the production of a new nerve cell
(neurogenesis).
• Then, individual neurons develop new connections to each other.
• A neuron works by sending or receiving electrochemical signals with other
neurons in the brain.
• As each neuron develops connections to others, this results in growing
clusters of cells.
• This ongoing process provides fine-tuning of the neural architecture.
Neuroplasticity uses cascades of electrochemical signals that unfold as a
result of the expression of genetic codes through cell signal molecules.

16. Cell assembly theory
• Nerve cells work by producing electrochemical activity in the “synapses,”
which are gaps connecting the cells together. As a synaptic connection
fires more often, it grows more efficient, in what is known as “cell
assembly theory.” A phrase describing this phenomenon is “cells that fire
together wire together” (Lowel, 1992).
• The nerve connections grow stronger when one cell fires before the other,
rather than when they both fire simultaneously. Sequential firing produces
a causal relationship, enabling the nervous system to learn.

17. Physiotherapy Implications
Neuroplasticity is also a phenomenon that aids brain recovery after the
damage produced by events like stroke or traumatic injury. Physical
neurorehabilitation can enhance brain and neuromuscular adaptation. PT
for neurological patients is a comprehensive process that intends to teach,
guide, and promote brain plasticity, thus reducing the threats for any
functional and cognitive variations
Neuroplastic specific techniques in physiotherapy include
• Motor Learning
• Biofeedback
• Task Analysis and Task-Specific Training
• Neurodevelopmental treatment (Bobath)
• Constraint-Induced Movement Therapy (CIMT)
• Proprioceptive Neuromuscular Facilitation (PNF)