Neuroplasticity: An Overview

Ross D. Zafonte^*
*Correspondence: Ross D. Zafonte, Department of Human Health, Harvard Medical School, Boston, United States, Email:

Perspective

Neuroplasticity, also known as neural plasticity or brain plasticity, is the ability of neuronal networks in the brain to change through development and reorganisation. Individual neuron pathways developing new connections, as well as systemic changes such as cortical remapping, are examples of these modifications [1]. Neuroplasticity includes changes to circuits and networks as a result of acquiring a new skill, environmental influences, practise, and psychological stress. The ability of the nervous system to change its activity in response to intrinsic or external stimuli by changing its structure, functions, or connections is known as neuroplasticity or brain plasticity. Synaptic plasticity, or the ability of neurons to change the intensity and efficacy of synaptic transmission through a variety of activity-dependent mechanisms, is a fundamental characteristic of neurons [2-4].

It was formerly assumed that the brain ceased developing after the first few years of life, and that connections between the brain's nerve cells formed only during this "critical period" as a young kid, and that these connections stayed fixed in place as we grew older [5]. As a result, only young brains were thought to be 'plastic' and hence capable of forming new connections. Scientists believed that if a specific portion of the adult brain was destroyed, nerve cells would be unable to make new connections or heal, and the activities regulated by that area of the brain would be permanently lost. Previously, neuroplasticity was thought to be limited to children, but studies in the second half of the twentieth century demonstrated that many aspects of the brain may be modified (or "plastic") in adults as well. On the other hand, the developing brain is more malleable than the adult brain. The importance of activity-dependent plasticity in healthy development, learning, memory, and brain damage repair cannot be overstated [6].

The Principles of Psychology, published in 1890, William James coined the term "plasticity" to characterise human behaviour. Michele Vicenzo Malacarne, an Italian anatomist, described how he paired animals, trained one for years, and then dissected the other. He noticed that the cerebellums of the trained animals were substantially larger. These discoveries, however, were quickly forgotten. In his book The Principles of Psychology, published in 1890, William James proposed the hypothesis that the brain and its function are not fixed throughout maturity, but it was widely dismissed. Neuroscientists believed that the structure and function of the brain remained essentially same throughout maturity until the 1970s [7].

While the brain was commonly believed to be a nonrenewable organ in the early 1900s, Santiago Ramón y Cajal, the pioneer of neuroscience, created the term neuronal plasticity to describe nonpathological changes in the structure of adult brains. Cajal defined the neuron as the fundamental unit of the nervous system, which later served as an important foundation for the creation of the concept of neural plasticity, which was based on his famous Neuron theory. He invented the term "plasticity" to describe his studies on the central nervous system's breakdown and repair once a person reaches adulthood. Several neuroscientists used the term "plasticity" to describe the regene [8].

In 1923, Karl Lashley used rhesus monkeys to conduct experiments that demonstrated changes in brain circuits, which he interpreted as proof of plasticity. Despite this and other evidence of plasticity, neuroscientists were sceptical of the concept of neuroplasticity. Based on his research on brain dynamics, Justo Gonzalo concluded in 1945 that the "central" cortical mass (roughly equidistant from the visual, tactile, and auditory projection areas) would be a "manoeuvring mass," rather unspecific or multisensory, with the ability to increase neural excitability and re-organize activity through plasticity, in contrast to the activity of the projection areas [9].

Michael Merzenich is a neurologist who has been a pioneer in the field of neuroplasticity for over three decades. He's said things like "brain workouts may be as beneficial as pharmaceuticals in treating severe conditions like schizophrenia," "plasticity persists from cradle to grave," and "dramatic gains in cognitive functioning - how we learn, think, perceive, and recall are conceivable even in the elderly." Merzenich's work was influenced by a crucial discovery made by David Hubel and Torsten Wiesel in their work with kittens. As part of the experiment, one eye was sewed shut and the cortical brain maps were recorded. The portion was missing, which Hubel and Wiesel observed [10].

Neuroplasticity's main manifestations include:

• A change could be either temporal (functional) or geographical (structural) (structural). Short-term and long-term changes are two types of temporal change.

• Furthermore, a spatial shift occurs at synapses, within neurons, or within glial cells. Additionally, functional alterations occur at the level of individual neurons.

• An individual neuron goes through sequences such as excitatory postsynaptic potential, synapse strengthening, long-term potentiation, and long-term depression. Furthermore, structural alterations affect the population of neurons.

• The dendritic arbour, spine density, synapse number, synapse size, axonal arboru, receptor density, unmasking, pruning, cortical representation, structural thickness, and grey matter density are all linked to these changes.

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