The peripheral nervous system extends throughout our bodies like a network. It acts as a “scout” and reports external information to the spinal cord and on to the brain. Simultaneously, it forwards instructions from the brain through the spinal cord to the arms, legs, and other parts of the body. The nervous system and the body are in constant communication, using electrical signals.

The following are examples of how the central and the peripheral nervous systems work together:

• Our skin contains cells that are part of the peripheral nervous system. They send information via the spinal cord to the brain, such as the ambient temperature. When the brain receives the information “it’s hot,” it activates the sweat glands to cool the body down. When it gets the information “it’s cold”, it triggers muscle contractions to heat the body through shivering.
• Our nose is also part of the peripheral nervous system, detecting smells. The brain identifies the smell and reacts accordingly. Based on previous experiences, the smell of fresh cake stimulates our appetite.

Imagine our brain and spinal cord like a network of roads – some are used all the time, and some are hardly used at all. Motorways form the busiest roads. Routes seldom used fall into disrepair and become narrow paths with a cracked surface.

After a neurological injury, we need to start using the narrow paths more often to turn these into motorways. Slowly but steadily, the human brain and spinal cord start to improve these paths and create new motorways.

In neuroscience, the term “plasticity” refers to the brain’s and spinal cord’s ability to modify its cells’ architecture, structure, and function. The brain and spinal cord are adaptable like plastic. Hence the term “neuroplasticity”.

Do you remember what it was like to drive a car for the very first time? Placing the clutch, selecting a gear, looking over your shoulder to keep an eye on traffic – all of that can be very overwhelming. After gaining experience over time, driving happens virtually automatically. This is neuroplasticity at work!

Neurogenesis – continuous formation of new nerve cells (no matter the age!)

New synapses – new experiences create new nerve cell connections

Enhanced synapses – frequent repetition and practice strengthen nerve cell connections

Weakened synapses – unused connections become weaker or even inactive

A stroke, a traumatic brain injury (TBI), or a spinal cord injury (SCI) cause damage to some brain regions or to the spinal cord. To return to the metaphor: the neurological damage causes road closures. Depending on which brain or spinal cord areas are affected, either the roads from the brain to the body (efferent nerve fibres) or from the body to the brain (afferent nerve fibres) become hard to navigate. The results are paralysis, spasticity, and/or perceptual disorders.

Learning and training change the brain and spinal cord. The nervous system looks automatically for new routes if one road is closed. The more frequently we use these new roads, the broader they get, and the more navigable they become.

After a stroke, movement of the fingers may be limited. Targeted training during rehabilitation may stimulate new and/or improved connections to form. Improved neuropathways may make it possible to move the fingers once more.

This phenomenon is well known by musicians. Research has shown that in players of bowed instruments, the areas in the cerebral cortex controlling finger movements are larger than in individuals who have never learned to play an instrument. Practice makes perfect! This training principle applies to rehabilitation as well.

Neurological damage can feel final. But they may not be. Depending on the severity of the injury or disease, the nervous system can change and adapt.

Talk with your physician about the possibility of improved function via neuroplasticity after neurological damage or disease.

Author: Michaela Partel

Sources:

Annunciato, N. (2021). Training: Plastizität des Nervensystems. Vienna: Physiozentrum für Weiterbildung

De Gruyter, W. (2017). Pschyrembel. Klinisches Wörterbuch. 267th edition Berlin / Boston

Nowak, D. (2011). Handfunktionsstörungen in der Neurologie. Würzburg: Springer Verlag

Principles of Experience-Dependent Neural Plasticity: Implications for Rehabilitation After Brain Damage, 2008

De Marées, H. (2003). Sportphysiologie. Köln: Sportverlag Strauss                

Increased Cortical Representation of the Fingers of the Left Hand in String Players, 1995