Neuronal plasticity spans various neuronal remodeling processes that are essential conditions for learning experiences. Remodeling of synapses and synaptic connections occurs until the end of life and occurs in response to the use of individual structures. In neurodegenerative diseases, the brain loses its neuronal plasticity.
What is neuronal plasticity?
Neuronal plasticity spans various remodeling processes of neurons that are an essential condition for learning experiences. Nerve cell tissue exhibits a specific structure. This structure is also called neuronal structure and is subject to permanent remodeling processes. Although brain development is completed in early childhood, the neural tissue has by then by no means reached its final structure. In any case, a final structure of the brain never exists. The brain in particular is characterized by a high learning ability. This learning ability is largely due to the rebuilding ability and rebuilding readiness of the nerve tissue. The restructuring processes are also called neuronal plasticity and can affect a single nerve cell as well as entire brain areas. Restructuring in the sense of neuronal plasticity takes place depending on the specific use of certain nerve cells. Individual areas of neuronal plasticity are intrinsic and synaptic plasticity. Intrinsic plasticity allows neurons to tune their sensitivity to signals from neighboring neurons. Synaptic plasticity, on the other hand, refers to the connections between individual neurons. Neurons (nerve cells) form a network of individual connections among themselves. For example, one connection in memory corresponds to one memory content. Thanks to synaptic plasticity, useless connections can be broken again and new synaptic connections can be created.
Function and task
The central nervous system should be understood as one of the most complex regions of the entire body. Until a few decades ago, the prevailing assumption was that the neuronal structure of the brain was static from birth and had completed its development. This would mean that the brain does not change further until death. However, based on research, neuroanatomy and neurology have discovered the complex learning processes of the brain, which significantly change the structures of neurons and continue throughout life. Immediately after birth, infants already possess 100 billion individual nerve cells. A healthy adult does not possess many more individual cells. However, an infant’s neurons are still small and have few connections. After birth, differentiation and maturation of the individual cells begins. Only at this time do the first synaptic connections between neurons begin to form. Neuronal plasticity corresponds to the incessant processes of connection formation and connection dissolution. The intensity of these remodeling processes depends on age. Many regions of the brain, for example, slow down their remodeling capacity with the years of life. However, a basic remodeling capacity remains until death. Neuronal plasticity is the essential condition for learning processes of all kinds and also contributes to memory performance. The life course of the individual determines which areas of the brain are particularly heavily used. The synaptic connections are then most extensive in these areas. The brain of a musician thus has strong connections in other areas than the brain of a doctor. Memory performance and knowledge performance can also be understood as synaptic connections. Depending on how often these connections are used, the nervous system is rebuilt. For example, the synaptic connections of memory and knowledge contents are more likely to be retained if the respective thoughts or memory are frequently recalled to consciousness. The brain thus works more efficiently and retains only connections that are experientially needed. Less frequently used connections give way and make room for new connections with higher relevance.
Diseases and ailments
Neuronal plasticity has nothing to do with regenerative capacity. The nervous tissue of the central nervous system is highly specialized. The more specialized types of tissue are, the less regenerative they are.For this reason, the brain is much less able to recover from injuries than, for example, skin and tissue during wound healing. In childhood, brain injuries can be compensated for far better than after the developmental phase has been completed. When nerve tissue within the brain dies due to an undersupply of oxygen, traumatic injury, or inflammation, that nerve tissue cannot be replaced. However, the brain may be able to relearn and thus compensate for the injury-related deficits. In stroke patients, for example, it has been observed that the fully functional nerve cells in the immediate vicinity of the dead ones take over the tasks of the damaged brain areas.
This takeover of functions from other brain areas requires, above all, targeted training. Based on these correlations, walking ability has been documented again in people with walking disabilities after a stroke, for example. The fact that such successes have been observed has to do with the neuronal plasticity of the brain in the broadest sense. Dead nerve tissue no longer possesses neuronal plasticity and cannot regain it. Nevertheless, neuronal plasticity remains in the intact brain areas. The loss of neuronal plasticity can be particularly understood in patients with degenerative brain diseases. In these brain diseases, the neurons of the brain degrade bit by bit. Such a degradation is inevitably accompanied by the loss of neuronal plasticity and thus also by the loss of learning ability. In addition to Alzheimer’s disease, the best-known brain diseases with degenerative consequences include Huntigton’s disease and Parkinson’s disease. Unlike stroke patients, transfer of individual functions to adjacent brain areas is not readily possible in the context of neurodegenerative diseases.
