A lie-to-children is a simplified, and often technically incorrect, explanation of technical or complex subjects employed as a teaching method. It is usually not done with an intent to deceive, but instead seek to 'meet the child/pupil/student where they are', in order to facilitate initial comprehension, which they build upon over time as the learner's intellectual capacity expands. The technique has been incorporated by academics within the fields of biology, evolution, bioinformatics and the social sciences.
They further elaborated upon their views in Figments of Reality: The Evolution of the Curious Mind, stating that the lie-to-children concept reflected the difficulty inherent in reducing complex concepts during the education process. Stewart and Cohen noted that "[a]ny description suitable for human minds to grasp must be some type of lie-to-children", and that the truth is "much too complicated for our limited minds".
The concept gained greater exposure when Cohen and Stewart co-authored The Science of Discworld with author Terry Pratchett. In this book, the authors acknowledge that some people might dispute the applicability of the term lie, while defending it on the grounds that "it is for the best possible reasons, but it is still a lie". In an interview promoting the book, Pratchett cautioned: "Most of us need just 'enough' knowledge of the sciences, and it's delivered to us in metaphors and analogies that bite us in the bum if we think they're the same as the truth."
Examples in education
A typical example of a lie-to-children is found in physics and chemistry, where the Bohr model (one type of planetary model) of atomic electron shells is still often used to introduce atomic structure before moving on to more complex models based on modern quantum mechanics. In a sense, these Bohr model diagrams can be better understood as a schematic illustrating how many electrons are in which shell and/or the redistribution of electrons in an ionic bond or covalent bond.
Similarly in chemistry, students are often introduced to the Arrhenius definitions of acids and bases before being taught the more technically correct but more complex Brønsted–Lowry model, followed by the Lewis model. This order of teaching chemistry concepts also reflects the historical progression in the development of these models.
High school teachers and university instructors often explain at the outset that the model they are about to present is incomplete. An example of this was given by Gerald Sussman during the 1986 video recording of the Abelson–Sussman Lectures:
If we're going to understand processes and how we control them, then we have to have a mapping from the mechanisms of this procedure into the way in which these processes behave. What we're going to have is a formal, or semi-formal, mechanical model whereby you understand how a machine could, in fact, in principle, do this. Whether or not the actual machine really does what I'm about to tell you is completely irrelevant at this moment.
In fact, this is an engineering model, in the same way that, [for an] electrical resistor, we write down a model V = IR—it's approximately true, but it's not really true; if I put enough current through the resistor, it goes boom, so the voltage is not always proportional to the current, but for some purposes the model is appropriate.
In particular, the model we're going to describe right now, which I call the substitution model, is the simplest model that we have for understanding how procedures work and how processes work—how procedures yield processes.
And that substitution model will be accurate for most of the things we'll be dealing with in the next few days. But eventually, it will become impossible to sustain the illusion that that's the way the machine works, and we'll go to other, more specific and particular models that will show more detail.
Analysis
Comparison to other concepts
Andrew Sawyer compared the concept to that of science fiction in the article "Narrativium and Lies-to-children: 'Palatable Instruction' in The Science of Discworld", in which he wrote: "The 'lies-to-children' we tell ourselves about science are a different form of science fiction: one, perhaps where 'fiction' qualifies the word 'science'. They are 'fictions about science' rather than 'science fictions'."
Anthony Judge has noted that the concept itself is a lie-to-children for more complex concepts in the philosophy of science.
Writing for Forbes in 2015, physics professor and science journalist Chad Orzel explored how the University of California Museum of Paleontology initiative Understanding Science goes beyond a simple explanation of the scientific method in a lie-to-children format, and instead goes into more depth and specifics to directly inform others on how science impacts their daily quality of living.
Application across fields
Writing for Forbes, Tim Worstall commented on the lie-to-children's application in physics and music, where lessons on scales precede those on atonality, common time and half time precede syncopation. He noted that Newton's physics is a lie-to-children compared to Einstein's additions.
In Nonlinear Dynamics in the Life and Social Sciences, Jack Cohen discussed the application of lies-to-children to teaching evolution, including the notion of DNA's purpose as a "blueprint", stating that "[o]nly the search for universal features, while treasuring all the exceptional specifics, offers some hope of sketching out the general shape of the evolutionary process so that we can explain it honestly as a Lie-to-Children". Similarly, in Bioinformatics, Biocomputing and Perl, authors Michael Moorhouse and Paul Barry explained how the lie-to-children model may be utilized as a teaching technique for the concepts of protein, RNA, and DNA.
In a computer science paper on linear algebra instruction, D.J. Jeffrey and Robert M. Corless from the University of Western Ontario identified an example from early childhood mathematics instruction: "We happily teach children that 'you cannot take 3 from 2' because we are confident that someone will later introduce them to negative numbers." Corless followed up on this view in a subsequent paper, stating that "mathematics before computers was a lie to children".
Drawbacks
In Evolving the Alien: The Science of Extraterrestrial Life, Cohen and Stewart themselves warned of a potential side effect of lies-to-children in reducing complex science concepts to overly simplified explanations. In a paper published in Digital Difference, Jen Ross and Hamish Macleod wrote that lies-to-children can have a negative impact on learners by setting an unreasonable expectation for "simple and unambiguous questions and equally simple answers".
In the journal Metaphilosophy, Kirsten Walsh and Adrian Currie drew a distinction between "caricature" and "mythmaking" in the framework of lies-to-children, and concluded that mythmaking is unjustified. North Eastern Hill University economics professor Sudhanshu K. Mishra explored the use of mythology in parenting, such as the case of parents telling children that they were brought by a stork to the house, instead of providing a more adequate explanation of childbirth. In The Children's Bill of Emotional Rights, Eileen Johnson discussed the problems that childhood mythology could cause in the future during the parenting process. Johnson cautioned that the lie must eventually be revealed, and that parents "are not sure how much of this deceit is right, how far to go with it, and how and when to explain it was all a lie".
In a column for the Carleton College blog Earth and Mind, geophysicist Kim Kastens and her daughter Dana Chayes listed potential pitfalls, such as how a lie-to-children that must later be unlearned may provide a potential obstacle to subsequent teachers, or how a student may discern the lie. They also listed criteria to avoid the pitfalls, such as ensuring that the teacher understands the truth beyond the lie-to-children, and having a "master plan" of a learning progression that the lies-to-children work toward. In a contribution to Teaching Bilingual/Bicultural Children, Haroom Kharem and Genevieve Collura asserted that the revelation of lie-to-children makes educators seem disingenuous and undermines students' respect for them.
In sociology, a social organization is a pattern of relationships between and among individuals and groups. Characteristics of social organization can include qualities such as sexual composition, spatiotemporal cohesion, leadership, structure, division of labor, communication systems, and so on.
Because of these characteristics of social organization, people can monitor their everyday work and involvement in other activities that are controlled forms of human interaction. These interactions include: affiliation, collective resources, substitutability of individuals and recorded control. These interactions come together to constitute common features in basic social units such as family, enterprises, clubs, states, etc. These are social organizations.
Social organizations are present in everyday life. Many people belong to various social structures, both institutional and informal. These include clubs, professional organizations, and religious institutions. Physical proximity with other members can strengthen a sense of community and shared identity within a social organization. While organizations link people with shared interests or goals, membership can also produce boundaries between members and non-members. Social organizations typically have some hierarchical structure. The form that hierarchy takes influences how a group is structured and how stable it tends to be over time.
Four other interactions can also bear on whether a group stays together. A group must have a strong affiliation within itself. To be affiliated with an organization means having a recognized connection and acceptance within that group, along with an obligation to return to it. The organization draws power through the collective resources of its affiliates. Those affiliates often have something invested in those resources, which motivates continued participation. At the same time, the organization must account for the substitutability of individuals: it needs affiliates and their resources to survive, but it also needs to be able to replace departing members. Given all these dynamics, internal coordination can be difficult. Recorded control — writing things down — makes processes clearer and keeps the organization coherent.
Within society
Social organizations within society change over time. Smaller-scale social organizations include groups that form from common interests and conversations.
These small organizations — bands, clubs, sports teams — have the same structural characteristics as large-scale organizations, even if their membership is far smaller. They still interact and function in similar ways.
A school sports team is a clear example. Members share a common goal and work together toward it. Different roles or positions divide the labor. The structure, while informal, is real: there are coaches, captains, and players, each with distinct responsibilities.
Large-scale organizations typically involve some degree of bureaucracy: a set of rules, specializations, and a hierarchical system, which allows them to pursue efficiency at scale. These organizations tend to rely on impersonal authority, where the position of power is structurally defined and kept separate from personal relationships, so that operations run predictably regardless of who holds a given role.
A hospital is one example of a large social organization. Within the hospital's overarching social structure we sometimes find smaller social structures such as within the nursing staff, the surgery team, facilities and operations teams. These smaller social structures work closely together on specific-to-their-role tasks. As a large social organization, a hospital may daily demonstrate relationships among staff and with patients, as well as the division of labor, structure, cohesion, and communication systems. This example serves to demonstrate how these smaller networks and structures serve to facilitate the larger structure's operations and objective. A 2023 study on the collaborative and professional boundary challenges within a hospital ward found that, "To safely discharge patients, the professionals needed
to talk about each other’s professional responsibilities" (Bjork,M., 2024, p.389). In other words, the social structure necessary for patient health relies on multiple networks.
Whether bureaucracy and hierarchical management are effective also depends on the structure of work within the organization. Organizations where departments operate independently of one another — called parallel organizations — do not necessarily benefit from top-down hierarchical control, because the diversity of functions makes centralized coordination difficult. Interdependent organizations, where departments rely on each other to complete tasks, tend to be better suited to hierarchical management because the work requires coordination across the whole.
Societies can be organized through individualistic or collectivist means. Each orientation has documented associations with different patterns in economic behavior, legal and political institutions, and social relations. The organization of a society is shaped by its cultural, historical, social, political, and economic context, which in turn governs how members interact.
Collectivist or individualist orientations can exist within a single broader society. Studies have examined differences in collectivism between regions of the US and between regions of China.Researchers have also examined historical factors linked to these differences, such as histories of rice and wheat farming in different regions of China and patterns of frontier settlement in the western United States.
Collectivism
Some scholars argue that the core unit of collectivism is the group. Others argue that "group" is too broad and that the focus is specific, close relationships. Individuals are seen as fundamentally connected through relationships and group membership. In this context, groups are defined as networks of interpersonal relationships. The collectivist orientation places emphasis on collective identity and collective agency, and values tend to prioritize the group over the individual.
However, common misunderstandings of collectivism are that it entails trust, warmth, and a rejection of competition. Studies have found that people in collectivistic cultures endorse competition more than people in individualistic cultures. Other research has found that people in collectivistic cultures are more mistrusting of people in their social circles (sometimes called "frienemies"). This can happen because collectivism involves strong ties between people, often with less freedom to choose relationships and leave conflictual relationships.
Some researchers measure collectivism through behaviors such as living arrangements, rates of multi-generational households, and divorce rates. Psychologically, collectivism is associated with what researchers call "holistic thought," which attends to relationships between objects, context, and a broader range of information simultaneously. And studies have found that getting people to think about social relationships in laboratory experiments makes people think more holistically.
Collectivist social organization may be horizontal or vertical. Horizontal models stress relationships within communities rather than a social hierarchy between them.
This kind of system has been associated with cultures with strong religious, ethnic, or familial group ties.
Individualism
An individualist orientation places emphasis on the individual through self-identity, individual agency, and values that tend to prioritize the individual over the collective. Psychologically, individualist orientations are associated with a tendency to distinguish, separate, and contrast information rather than integrate or assimilate it. Individualist social organization has been linked to different institutional forms, including arrangements that prioritize personal autonomy, contract-based cooperation, and formal legal structures for coordinating behavior between people who do not share strong group ties. However, individualism has also been associated with rising loneliness & isolation.
Regional Associations
Most research on individualism has been conducted in the United States, Germany, and the Netherlands. Most research on collectivism has come from East Asia.
European data has drawn predominantly from Germany and the Netherlands. Scandinavian countries (which have a more egalitarian culture), southern Europe, and Eastern Europe are underrepresented in this data. Africa, West Asia, and Latin American countries are also absent from much of the research. The literature does not substantially cover countries with Islamic culture or countries experiencing within-group conflict.
Online
Social organizations can exist in digital spaces, and online communities show patterns of interaction similar to those in in-person social groups. The technology allows people to engage with social organizations without being in the same physical location.
Although the characteristics of online organizations differ in some ways from those of in-person groups, the structural parallels are clear. Various forms of online communication allow people to talk, share interests, and maintain membership in a group without physical presence. These online groups still function as social organizations because of the relationships within them and the shared interest in sustaining the community.
Neuroplasticity, also known as neural plasticity or simply plasticity, is the tendency of neural networks in the brain to change through growth and reorganization. Neuroplasticity refers to the brain's ability to reorganize and rewire its neural connections, enabling it to adapt and function in ways that differ from its prior state. This process can occur in response to learning new skills, experiencing environmental changes, recovering from injuries, or adapting to sensory or cognitive deficits. Such adaptability highlights the dynamic and ever-evolving nature of the brain, even into adulthood. These changes range from individual neuron pathways making new connections, to systematic adjustments like cortical remapping or neural oscillation. Other forms of neuroplasticity include homologous area adaptation, cross modal reassignment, map expansion, and compensatory masquerade. Examples of neuroplasticity include circuit and network changes that result from learning a new ability, information acquisition, socio-environmental influences, pregnancy, caloric intake, practice/training, and psychological stress.
Neuroplasticity was once thought by neuroscientists to manifest only during childhood, but research in the later half of the 20th century showed that many aspects of the brain exhibit plasticity through adulthood. The developing brain exhibits a higher degree of plasticity than the adult brain. Activity-dependent plasticity can have significant implications for healthy development, learning, memory, and recovery from brain damage.
History
Origin
The term plasticity was first applied to behavior in 1890 by William James in The Principles of Psychology where the term was used to describe "a structure weak enough to yield to an influence, but strong enough not to yield all at once". The first person to use the term neural plasticity appears to have been the Polish neuroscientist Jerzy Konorski.
One of the first experiments providing evidence for neuroplasticity was conducted in 1793, by Italian anatomist Michele Vincenzo Malacarne, who described experiments in which he paired animals, trained one of the pair extensively for years, and then dissected both. Malacarne discovered that the cerebellums of the trained animals were substantially larger than the cerebellum of the untrained animals. However, while these findings were significant, they were eventually forgotten. In 1890, the idea that the brain and its function are not fixed throughout adulthood was proposed by William James in The Principles of Psychology, though the idea was largely neglected. Up until the 1970s, neuroscientists believed that the brain's structure and function was essentially fixed throughout adulthood.
While the brain was commonly understood as a nonrenewable organ in the early 1900s, the pioneering neuroscientist Santiago Ramón y Cajal used the term neuronal plasticity to describe nonpathological changes in the structure of adult brains. Based on his renowned neuron doctrine, Cajal first described the neuron as the fundamental unit of the nervous system that later served as an essential foundation to develop the concept of neural plasticity. Many neuroscientists used the term plasticity to explain the regenerative capacity of the peripheral nervous system only. Cajal, however, used the term plasticity to reference his findings of degeneration and regeneration in the adult brain (a part of the central nervous system). This was controversial, with some like Walther Spielmeyer and Max Bielschowsky arguing that the CNS cannot produce new cells.
The term has since been broadly applied:
Given the central importance of neuroplasticity, an outsider would be forgiven for assuming that it was well defined and that a basic and universal framework served to direct current and future hypotheses and experimentation. Sadly, however, this is not the case. While many neuroscientists use the word neuroplasticity as an umbrella term it means different things to different researchers in different subfields ... In brief, a mutually agreed-upon framework does not appear to exist.
Research and discovery
In 1923, Karl Lashley conducted experiments on rhesus monkeys that demonstrated changes in neuronal pathways, which he concluded were evidence of plasticity. Despite this, and other research that suggested plasticity, neuroscientists did not widely accept the idea of neuroplasticity.
In 1945, Justo Gonzalo concluded from his research on brain dynamics, that, contrary to the activity of the projection areas, the "central" cortical mass (more or less equidistant from the visual, tactile and auditive projection areas), would be a "maneuvering mass", rather unspecific or multisensory, with capacity to increase neural excitability and re-organize the activity by means of plasticity properties. He gives as a first example of adaptation, to see upright with reversing glasses in the Stratton experiment, and specially, several first-hand brain injuries cases in which he observed dynamic and adaptive properties in their disorders, in particular in the inverted perception disorder. He stated that a sensory signal in a projection area would be only an inverted and constricted outline that would be magnified due to the increase in recruited cerebral mass, and re-inverted due to some effect of brain plasticity, in more central areas, following a spiral growth.
Marian Diamond of the University of California, Berkeley, produced the first scientific evidence of anatomical brain plasticity, publishing her research in 1964.
Other significant evidence was produced in the 1960s and after, notably from scientists including Paul Bach-y-Rita, Michael Merzenich along with Jon Kaas, as well as several others. An attempt to describe the mechanisms of neuroplasticity, an early version of the computational theory of mind derived from Hebb's work, was put forward by Peter Putnam and Robert W. Fuller in that time.
In the 1960s, Paul Bach-y-Rita invented a device that was tested on a small number of people, and involved a person sitting in a chair, embedded in which were nubs that were made to vibrate in ways that translated images received in a camera, allowing a form of vision via sensory substitution.
Studies in people recovering from stroke also provided support for neuroplasticity, as regions of the brain that remained healthy could sometimes take over, at least in part, functions that had been destroyed; Shepherd Ivory Franz did work in this area.
Eleanor Maguire documented changes in hippocampal structure associated with acquiring the knowledge of London's layout in local taxi drivers. A redistribution of grey matter was indicated in London Taxi Drivers compared to controls. This work on hippocampal plasticity not only interested scientists, but also engaged the public and media worldwide.
Michael Merzenich is a neuroscientist who has been one of the pioneers of neuroplasticity for over three decades. He has made some of "the most ambitious claims for the field – that brain exercises may be as useful as drugs to treat diseases as severe as schizophrenia – that plasticity exists from cradle to the grave, and that radical improvements in cognitive functioning – how we learn, think, perceive, and remember are possible even in the elderly." Merzenich's work was affected by a crucial discovery made by David Hubel and Torsten Wiesel in their work with kittens. The experiment involved sewing one eye shut and recording the cortical brain maps. Hubel and Wiesel saw that the portion of the kitten's brain associated with the shut eye was not idle, as expected. Instead, it processed visual information from the open eye. It was "…as though the brain didn't want to waste any 'cortical real estate' and had found a way to rewire itself."
This implied neuroplasticity during the critical period. However, Merzenich argued that neuroplasticity could occur beyond the critical period. His first encounter with adult plasticity came when he was engaged in a postdoctoral study with Clinton Woosley. The experiment was based on observation of what occurred in the brain when one peripheral nerve was cut and subsequently regenerated. The two scientists micromapped the hand maps of monkey brains before and after cutting a peripheral nerve and sewing the ends together. Afterwards, the hand map in the brain that they expected to be jumbled was nearly normal. This was a substantial breakthrough. Merzenich asserted that, "If the brain map could normalize its structure in response to abnormal input, the prevailing view that we are born with a hardwired system had to be wrong. The brain had to be plastic." Merzenich received the 2016 Kavli Prize in Neuroscience "for the discovery of mechanisms that allow experience and neural activity to remodel brain function."
Neurobiology
There are different ideas and theories on what biological processes allow for neuroplasticity to occur. The core of this phenomenon is based upon synapses and how connections between them change based on neuron functioning. It is widely agreed upon that neuroplasticity takes on many forms, as it is a result of a variety of pathways. These pathways, mainly signaling cascades, allow for gene expression alterations that lead to neuronal changes, and thus neuroplasticity.
There are a number of other factors that are thought to play a role in the biological processes underlying the changing of neural networks in the brain. Some of these factors include synapse regulation via phosphorylation, the role of inflammation and inflammatory cytokines, proteins such as Bcl-2 proteins and neutrophorins, energy production via mitochondria, and acetylcholine.
JT Wall and J Xu have traced the mechanisms underlying neuroplasticity. Re-organization is not cortically emergent, but occurs at every level in the processing hierarchy; this produces the map changes observed in the cerebral cortex.
Types
Christopher Shaw and Jill McEachern (eds) in "Toward a theory of Neuroplasticity", state that there is no all-inclusive theory that overarches different frameworks and systems in the study of neuroplasticity. However, researchers often describe neuroplasticity as "the ability to make adaptive changes related to the structure and function of the nervous system." Correspondingly, two types of neuroplasticity are often discussed: structural neuroplasticity and functional neuroplasticity.
Structural neuroplasticity
Structural Neuroplasticity (also referred to as Structural Plasticity) can be defined as the brain's ability to physically change its anatomical structure through alterations and/or new developments as a result of external stimuli or damage. This biological occurrence typically happens when changes are made to existing neural circuits (Ex. The creation of new dendritic spines), axonal sprouting, and neurogenesis (the creation of new neurons). The relevance behind structural neuroplasticity can be traced back to the importance of the generalities of neuroplasticity. Neuroplasticity is important because it's a biological occurrence that allows the brain to adapt to the influx of new information that is gained during human development; typically accomplished through the reorganization of its structure, functions, and/or connections. These changes allow humans to adapt to everyday life and play an important role in learning and memory. Structural neuroplasticity accomplishes this objective by focusing on altering and creating new anatomical brain structures through the process of neurogenesis.
The changes of grey matter proportion or the synaptic strength in the brain are considered as examples of structural neuroplasticity. This type of neuroplasticity often studies the effect of various internal or external stimuli on the brain's anatomical reorganization. New neurons are constantly produced and integrated into the central nervous system based on this type of neuroplasticity. Researchers nowadays use multiple cross-sectional imaging methods (i.e. magnetic resonance imaging (MRI), computerized tomography (CT)) to study the structural alterations of the human brains. Structural neuroplasticity is currently investigated more within the field of neuroscience in current academia. Adult neurogenesis "has not been convincingly demonstrated in humans". However, some new neurons can be formed in the subgranular zone of the hippocampal dentate gyrus & the subventricular zone of the lateral ventriclesand has been found to play an important role in emotional and cognitive functions such as spatial learning, memory, pattern separation, & mood regulation. It has also been shown that there are endogenous mechanisms (found in the adult brain) to aid in brain repair when damage to the brain has occurred, another reason why structural neuroplasticity is important.
Functional neuroplasticity
Functional plasticity refers to the brain's ability to alter and adapt the functional properties of network of neurons. It can occur in four known ways namely:
homologous area adaptation
map expansion
cross-model reassignment
compensatory masquerade.
Homologous area adaptation
Homologous area adaptation is the assumption of a particular cognitive process by a homologous region in the opposite hemisphere. For instance, through homologous area adaptation a cognitive task is shifted from a damaged part of the brain to its homologous area in opposite side of the brain. Homologous area adaptation is a type of functional neuroplasticity that occur usually in children rather than adults.
Map expansion
In map expansion, cortical maps related to particular cognitive tasks expand due to frequent exposure to stimuli. Map expansion has been proven through experiments performed in relation to the study: experiment on effect of frequent stimulus on functional connectivity of the brain was observed in individuals learning spatial routes.
Cross-model reassignment
Cross-model reassignment involves reception of novel input signals to a brain region which has been stripped of its default input.
Compensatory masquerade
Functional plasticity through compensatory masquerade occurs using different cognitive processes for an already established cognitive task when the initial process cannot be followed due to impairment.
Changes in the brain associated with functional neuroplasticity can occur in response to two different types of events:
in response to malfunction or damage of neurons (maladaptive plasticity) to compensate a pathological event
In the latter case the functions from one part of the brain transfer to another part of the brain based on the demand to produce recovery of behavioral or physiological processes. Regarding physiological forms of activity-dependent plasticity, those involving synapses are referred to as synaptic plasticity. The strengthening or weakening of synapses that results in an increase or decrease of firing rate of the neurons are called long-term potentiation (LTP) and long-term depression (LTD), respectively, and they are considered as examples of synaptic plasticity that are associated with memory. The cerebellum is a typical structure with combinations of LTP/LTD and redundancy within the circuitry, allowing plasticity at several sites. More recently it has become clearer that synaptic plasticity can be complemented by another form of activity-dependent plasticity involving the intrinsic excitability of neurons, which is referred to as intrinsic plasticity. This, as opposed to homeostatic plasticity does not necessarily maintain the overall activity of a neuron within a network but contributes to encoding memories. Also, many studies have indicated functional neuroplasticity in the level of brain networks, where training alters the strength of functional connections. Although a recent study discusses that these observed changes should not directly relate to neuroplasticity, since they may root in the systematic requirement of the brain network for reorganization.
Applications and examples
The adult brain is not entirely "hard-wired" with fixed neuronal circuits. There are many instances of cortical and subcortical rewiring of neuronal circuits in response to training as well as in response to injury.
There is ample evidence for the active, experience-dependent re-organization of the synaptic networks of the brain involving multiple inter-related structures including the cerebral cortex. The specific details of how this process occurs at the molecular and ultrastructural levels are topics of active neuroscience research. The way experience can influence the synaptic organization of the brain is also the basis for a number of theories of brain function including the general theory of mind and neural Darwinism. The concept of neuroplasticity is also central to theories of memory and learning that are associated with experience-driven alteration of synaptic structure and function in studies of classical conditioning in invertebrate animal models such as Aplysia.
There is evidence that neurogenesis (birth of brain cells) occurs in the adult, rodent brain—and such changes can persist well into old age. The evidence for neurogenesis is mainly restricted to the hippocampus and olfactory bulb, but research has revealed that other parts of the brain, including the cerebellum, may be involved as well. However, the degree of rewiring induced by the integration of new neurons in the established circuits is not known, and such rewiring may well be functionally redundant.
Neuroscientists believe that drug addicts’ behavior is a direct correlation to some physiological change in their brain, caused by using drugs. This view believes there is a bodily function in the brain causing the addiction. This is brought on by a change in the brain caused by brain damage or adaptation from chronic drug use.
The VTA is the portion of the mesolimbic system responsible for spreading dopamine to the whole system. The VTA is stimulated by ″rewarding experiences″. The release of dopamine by the VTA induces pleasure, thus reinforcing behaviors that lead to the reward. Drugs of abuse increase the VTA's ability to project dopamine to the rest of the reward circuit. These structural changes only last 7–10 days, however, indicating that the VTA cannot be the only part of the brain that is affected by drug use, and changed during the development of addiction.
The nucleus accumbens (NAc) plays an essential part in the formation of addiction. Almost every drug with addictive potential induces the release of dopamine into the NAc. In contrast to the VTA, the NAc shows long-term structural changes. Drugs of abuse weaken the connections within the NAc after habitual use, as well as after use then withdrawal.
Treatment of brain damage
A surprising consequence of neuroplasticity is that the brain activity associated with a given function can be transferred to a different location; this can result from normal experience and also occurs in the process of recovery from brain injury. Neuroplasticity is the fundamental issue that supports the scientific basis for treatment of acquired brain injury with goal-directed experiential therapeutic programs in the context of rehabilitation approaches to the functional consequences of the injury.
Neuroplasticity is gaining popularity as a theory that, at least in part, explains improvements in functional outcomes with physical therapy post-stroke. Rehabilitation techniques that are supported by evidence which suggest cortical reorganization as the mechanism of change include constraint-induced movement therapy, functional electrical stimulation, treadmill training with body-weight support, and virtual reality therapy. Robot assisted therapy is an emerging technique, which is also hypothesized to work by way of neuroplasticity, though there is currently insufficient evidence to determine the exact mechanisms of change when using this method.
One group has developed a treatment that includes increased levels of progesterone injections in brain-injured patients. "Administration of progesterone after traumatic brain injury (TBI) and stroke reduces edema, inflammation, and neuronal cell death, and enhances spatial reference memory and sensory-motor recovery." In a clinical trial, a group of severely injured patients had a 60% reduction in mortality after three days of progesterone injections. However, a study published in the New England Journal of Medicine in 2014 detailing the results of a multi-center NIH-funded phase III clinical trial of 882 patients found that treatment of acute traumatic brain injury with the hormone progesterone provides no significant benefit to patients when compared with placebo.
Binocular vision
For decades, researchers assumed that humans had to acquire binocular vision, in particular stereopsis, in early childhood or they would never gain it. In recent years, however, successful improvements in persons with amblyopia, convergence insufficiency or other stereo vision anomalies have become prime examples of neuroplasticity; binocular vision improvements and stereopsis recovery are now active areas of scientific and clinical research.
Phantom limbs
A diagrammatic explanation of the mirror box. The patient places the intact limb into one side of the box (in this case the right hand) and the amputated limb into the other side. Due to the mirror, the patient sees a reflection of the intact hand where the missing limb would be (indicated in lower contrast). The patient thus receives artificial visual feedback that the "resurrected" limb is now moving when they move the good hand.
In the phenomenon of phantom limb sensation, a person continues to feel pain or sensation within a part of their body that has been amputated. This is strangely common, occurring in 60–80% of amputees. An explanation for this is based on the concept of neuroplasticity, as the cortical maps of the removed limbs are believed to have become engaged with the area around them in the postcentral gyrus. This results in activity within the surrounding area of the cortex being misinterpreted by the area of the cortex formerly responsible for the amputated limb.
The relationship between phantom limb sensation and neuroplasticity is a complex one. In the early 1990s V.S. Ramachandran theorized that phantom limbs were the result of cortical remapping. However, in 1995 Herta Flor and her colleagues demonstrated that cortical remapping occurs only in patients who have phantom pain. Her research showed that phantom limb pain (rather than referred sensations) was the perceptual correlate of cortical reorganization. This phenomenon is sometimes referred to as maladaptive plasticity.
In 2009, Lorimer Moseley and Peter Brugger carried out an experiment in which they encouraged arm amputee subjects to use visual imagery to contort their phantom limbs into impossible configurations. Four of the seven subjects succeeded in performing impossible movements of the phantom limb. This experiment suggests that the subjects had modified the neural representation of their phantom limbs and generated the motor commands needed to execute impossible movements in the absence of feedback from the body.
Individuals who have chronic pain experience prolonged pain at sites that may have been previously injured, yet are otherwise currently healthy. This phenomenon is related to neuroplasticity due to a maladaptive reorganization of the nervous system, both peripherally and centrally. During the period of tissue damage, noxious stimuli and inflammation cause an elevation of nociceptive input from the periphery to the central nervous system. Prolonged nociception from the periphery then elicits a neuroplastic response at the cortical level to change its somatotopic organization for the painful site, inducing central sensitization. For instance, individuals experiencing complex regional pain syndrome demonstrate a diminished cortical somatotopic representation of the hand contralaterally as well as a decreased spacing between the hand and the mouth. Additionally, chronic pain has been reported to significantly reduce the volume of grey matter throughout the brain, particularly at the prefrontal cortex and right thalamus. However, following treatment, these abnormalities in cortical reorganization and grey matter volume are resolved, as well as their symptoms. Similar results have been reported for phantom limb pain, chronic low back pain and carpal tunnel syndrome.
Chronic pain and neuroplasticity can alter cognition and impair learning, attention, memory, and decision making. Clinical studies have shown that chronic pain remodels the brain both structurally (e.g. gray matter loss) and functionally. Pain is a complex, multidimensional condition that activates several biological processes when an injury or threat has occurred. Remodeling begins when there is an increase in neuroinflammation, an imbalance in neurotransmitters (GABA, glutamate, dopamine) and disruption in synaptic plasticity. When the brain undergoes reorganization, there is a transition that occurs. Pain switches from the sensory region of the brain to the emotional and the limbic regions where pain is amplified and becomes chronic. The areas of the brain that undergo structural and functional changes in the corticolimbic system are: The prefrontal cortex, the anterior cingulate cortex, the amygdala, and the hippocampus. When these structures are changed because of neuroplasticity, it causes cognitive dysfunction. Chronic pain and neuroplasticity impairs learning, attention, memory, and decision making and can cause adverse emotions, such as depression and anxiety.
A number of studies have linked meditation practice to differences in cortical thickness or density of gray matter. One of the most well-known studies to demonstrate this was led by Sara Lazar, from Harvard University, in 2000. Richard Davidson, a neuroscientist at the University of Wisconsin, has led experiments in collaboration with the Dalai Lama on effects of meditation on the brain. His results suggest that meditation may lead to change in the physical structure of brain regions associated with attention, anxiety, depression, fear, anger, and compassion as well as the ability of the body to heal itself.
Artistic engagement and art therapy
There is substantial evidence that artistic engagement in a therapeutic environment can create changes in neural network connections as well as increase cognitive flexibility. In one 2013 study, researchers found evidence that long-term, habitual artistic training (e.g. musical instrument practice, purposeful painting, etc.) can "macroscopically imprint a neural network system of spontaneous activity in which the related brain regions become functionally and topologically modularized in both domain-general and domain-specific manners". In simple terms, brains repeatedly exposed to artistic training over long periods develop adaptations to make such activity both easier and more likely to spontaneously occur.
Some researchers and academics have suggested that artistic engagement has substantially altered the human brain throughout our evolutionary history. D.W Zaidel, adjunct professor of behavioral neuroscience and contributor at VAGA, has written that "evolutionary theory links the symbolic nature of art to critical pivotal brain changes in Homo sapiens supporting increased development of language and hierarchical social grouping".
Music therapy
There is evidence that engaging in music-supported therapy can improve neuroplasticity in patients who are recovering from brain injuries. Music-supported therapy can be used for patients that are undergoing stroke rehabilitation where a one-month study of stroke patients participating in music-supported therapy showed a significant improvement in motor control in their affected hand. Another finding was the examination of grey matter volume of adults developing brain atrophy and cognitive decline where playing a musical instrument, such as the piano, or listening to music can increase grey matter volume in areas such as the caudate nucleus, Rolandic operculum, and cerebellum. Evidence also suggests that music-supported therapy can improve cognitive performance, well-being, and social behavior in patients who are recovering from damage to the orbitofrontal cortex (OFC) and recovering from mild traumatic brain injury. Neuroimaging post music-supported therapy revealed functional changes in OFC networks, with improvements observed in both task-based and resting-state fMRI analyses.
Beyond clinical rehabilitation, music has been shown to induce neuroplastic changes in healthy individuals through long-term training and repeated exposure. Studies comparing musicians and non-musicians have demonstrated structural and functional brain differences associated with musical practice, particularly when training begins early in life.[98] Musicians often exhibit increased gray and white matter volume in motor, auditory, and cerebellar regions, reflecting adaptations related to fine motor control, auditory processing, and timing. Evidence of cortical remapping has also been observed, such as enlarged cortical representations of the fingers most frequently used during instrument performance.
Music training strongly affects the auditory system, with musicians showing enhanced activation and structural differences in primary and secondary auditory cortices involved in processing pitch, rhythm, and melody. Functional changes have been observed not only at the cortical level but also in subcortical structures, including the brainstem, where musicians demonstrate faster and stronger neural responses to sound. Across the lifespan, sustained musical engagement has been associated with reduced age-related decline in certain brain regions and a lower risk of cognitive impairment, suggesting that music-related neuroplasticity may contribute to long-term brain health.
Due to hearing loss, the auditory cortex and other association areas of the brain in deaf and/or hard of hearing people undergo compensatory plasticity. The auditory cortex usually reserved for processing auditory information in hearing people now is redirected to serve other functions, especially for vision and somatosensation.
Deaf individuals have enhanced peripheral visual attention, better motion change but not color change detection ability in visual tasks, more effective visual search, and faster response time for visual targets compared to hearing individuals. Altered visual processing in deaf people is often found to be associated with the repurposing of other brain areas including primary auditory cortex, posterior parietal association cortex (PPAC), and anterior cingulate cortex (ACC). A review by Bavelier et al. (2006) summarizes many aspects on the topic of visual ability comparison between deaf and hearing individuals.
Brain areas that serve a function in auditory processing repurpose to process somatosensory information in congenitally deaf people. They have higher sensitivity in detecting frequency change in vibration above threshold and higher and more widespread activation in auditory cortex under somatosensory stimulation. However, speeded response for somatosensory stimuli is not found in deaf adults.
Cochlear implant
Neuroplasticity is involved in the development of sensory function. The brain is born immature and then adapts to sensory inputs after birth. In the auditory system, congenital hearing loss, a rather frequent inborn condition affecting 1 of 1000 newborns, has been shown to affect auditory development, and implantation of a sensory prostheses activating the auditory system has prevented the deficits and induced functional maturation of the auditory system. Due to a sensitive period for plasticity, there is also a sensitive period for such intervention within the first 2–4 years of life. Consequently, in prelingually deaf children, early cochlear implantation, as a rule, allows the children to learn the mother language and acquire acoustic communication.
Blindness
Due to vision loss, the visual cortex in blind people may undergo cross-modal plasticity, and therefore other senses may have enhanced abilities. Or the opposite could occur, with the lack of visual input weakening the development of other sensory systems. One study suggests that the right posterior middle temporal gyrus and superior occipital gyrus reveal more activation in the blind than in the sighted people during a sound-moving detection task. Several studies support the latter idea and found weakened ability in audio distance evaluation, proprioceptive reproduction, threshold for visual bisection, and judging minimum audible angle.
Human echolocation
Human echolocation is a learned ability for humans to sense their environment from echoes. This ability is used by some blind people to navigate their environment and sense their surroundings in detail. Studies in 2010 and 2011 using functional magnetic resonance imaging techniques have shown that parts of the brain associated with visual processing are adapted for the new skill of echolocation. Studies with blind patients, for example, suggest that the click-echoes heard by these patients were processed by brain regions devoted to vision rather than audition.
Reviews of MRI and electroencephalography (EEG) studies on individuals with ADHD suggest that the long-term treatment of ADHD with stimulants, such as amphetamine or methylphenidate, decreases abnormalities in brain structure and function found in subjects with ADHD, and improves function in several parts of the brain, such as the right caudate nucleus of the basal ganglia, left ventrolateral prefrontal cortex (VLPFC), and superior temporal gyrus.
In addition to pharmacological treatment, non-pharmacological interventions that leverage neuroplasticity have been proposed as potential approaches for managing ADHD symptoms. Cognitive training and other behavioral therapies aim to improve attention, self-regulation, and impulse control by promoting functional and structural changes in neural circuits associated with executive function. Computerized cognitive training programs have been shown to target underdeveloped neural networks in individuals with ADHD, leading to improvements in attention and working memory through repeated stimulation of specific brain regions. These interventions may produce longer-term neuroplastic changes that overlap with brain areas affected by stimulant medications, suggesting that neuroplasticity-based therapies could complement or, in some cases, reduce reliance on pharmacological treatment.
In early child development
Neuroplasticity is most active in childhood as a part of normal human development, and can also be seen as an especially important mechanism for children in terms of risk and resiliency. Trauma is considered a great risk as it negatively affects many areas of the brain and puts a strain on the sympathetic nervous system from constant activation. Trauma thus alters the brain's connections such that children who have experienced trauma may be hyper vigilant or overly aroused. However, a child's brain can cope with these adverse effects through the actions of neuroplasticity.
Neuroplasticity is shown in four different categories in children and covering a wide variety of neuronal functioning. These four types include impaired, excessive, adaptive, and plasticity.
There are many examples of neuroplasticity in human development. For example, Justine Ker and Stephen Nelson looked at the effects of musical training on neuroplasticity, and found that musical training can contribute to experience dependent structural plasticity. This is when changes in the brain occur based on experiences that are unique to an individual. Examples of this are learning multiple languages, playing a sport, doing theatre, etc. A study done by Hyde in 2009, showed that changes in the brain of children could be seen in as little as 15 months of musical training. Ker and Nelson suggest this degree of plasticity in the brains of children can "help provide a form of intervention for children... with developmental disorders and neurological diseases."
In a single lifespan, individuals of an animal species may encounter various changes in brain morphology. Many of these differences are caused by the release of hormones in the brain; others are the product of evolutionary factors or developmental stages. Some changes occur seasonally in species to enhance or generate response behaviors.
Seasonal brain changes
Changing brain behavior and morphology to suit other seasonal behaviors is relatively common in animals. These changes can improve the chances of mating during breeding season. Examples of seasonal brain morphology change can be found within many classes and species.
Within the class Aves, black-capped chickadees experience an increase in the volume of their hippocampus and strength of neural connections to the hippocampus during fall months. These morphological changes within the hippocampus which are related to spatial memory are not limited to birds, as they can also be observed in rodents and amphibians. In songbirds, many song control nuclei in the brain increase in size during mating season. Among birds, changes in brain morphology to influence song patterns, frequency, and volume are common. Gonadotropin-releasing hormone (GnRH) immunoreactivity, or the reception of the hormone, is lowered in European starlings exposed to longer periods of light during the day.
The California sea hare, a gastropod, has more successful inhibition of egg-laying hormones outside of mating season due to increased effectiveness of inhibitors in the brain. Changes to the inhibitory nature of regions of the brain can also be found in humans and other mammals. In the amphibian Bufo japonicus, part of the amygdala is larger before breeding and during hibernation than it is after breeding.
Seasonal brain variation occurs within many mammals. Part of the hypothalamus of the common ewe is more receptive to GnRH during breeding season than at other times of the year. Humans experience a change in the "size of the hypothalamic suprachiasmatic nucleus and vasopressin-immunoreactive neurons within it" during the fall, when these parts are larger. In the spring, both reduce in size.
Traumatic brain injury research
A group of scientists found that if a small stroke (an infarction) is induced by obstruction of blood flow to a portion of a monkey's motor cortex, the part of the body that responds by movement moves when areas adjacent to the damaged brain area are stimulated. In one study, intracortical microstimulation (ICMS) mapping techniques were used in nine normal monkeys. Some underwent ischemic-infarction procedures and the others, ICMS procedures. The monkeys with ischemic infarctions retained more finger flexion during food retrieval and after several months this deficit returned to preoperative levels. With respect to the distal forelimb representation, "postinfarction mapping procedures revealed that movement representations underwent reorganization throughout the adjacent, undamaged cortex." Understanding of interaction between the damaged and undamaged areas provides a basis for better treatment plans in stroke patients. Current research includes the tracking of changes that occur in the motor areas of the cerebral cortex as a result of a stroke. Thus, events that occur in the reorganization process of the brain can be ascertained. The treatment plans that may enhance recovery from strokes, such as physiotherapy, pharmacotherapy, and electrical-stimulation therapy, are also being studied.
Jon Kaas, a professor at Vanderbilt University, has been able to show "how somatosensory area 3b and ventroposterior (VP) nucleus of the thalamus are affected by longstanding unilateral dorsal-column lesions at cervical levels in macaque monkeys." Adult brains have the ability to change as a result of injury but the extent of the reorganization depends on the extent of the injury. His recent research focuses on the somatosensory system, which involves a sense of the body and its movements using many senses. Usually, damage of the somatosensory cortex results in impairment of the body perception. Kaas' research project is focused on how these systems (somatosensory, cognitive, motor systems) respond with plastic changes resulting from injury.
One recent study of neuroplasticity involves work done by a team of doctors and researchers at Emory University, specifically Donald Stein and David Wright. This is the first treatment in 40 years that has significant results in treating traumatic brain injuries while also incurring no known side effects and being cheap to administer. Stein noticed that female mice seemed to recover from brain injuries better than male mice, and that at certain points in the estrus cycle, females recovered even better. This difference may be attributed to different levels of progesterone, with higher levels of progesterone leading to the faster recovery from brain injury in mice. However, clinical trials showed progesterone offers no significant benefit for traumatic brain injury in human patients.
Aging
Transcriptional profiling of the frontal cortex of persons ranging from 26 to 106 years of age defined a set of genes with reduced expression after age 40, and especially after age 70. Genes that play central roles in synaptic plasticity were the most significantly affected by age, generally showing reduced expression over time. There was also a marked increase in cortical DNA damage, likely oxidative DNA damage, in gene promoters with aging.
Reactive oxygen species appear to have a significant role in the regulation of synaptic plasticity and cognitive function. However age-related increases in reactive oxygen species may also lead to impairments in these functions.
Multilingualism
There is a beneficial effect of multilingualism on people's behavior and cognition. Numerous studies have shown that people who study more than one language have better cognitive functions and flexibilities than people who only speak one language. Bilinguals are found to have longer attention spans, stronger organization and analyzation skills, and a better theory of mind than monolinguals. Researchers have found that the effect of multilingualism on better cognition is due to neuroplasticity.
In one prominent study, neurolinguists used a voxel-based morphometry (VBM) method to visualize the structural plasticity of brains in healthy monolinguals and bilinguals. They first investigated the differences in density of grey and white matter between two groups and found the relationship between brain structure and age of language acquisition. The results showed that grey-matter density in the inferior parietal cortex for multilinguals were significantly greater than monolinguals. The researchers also found that early bilinguals had a greater density of grey matter relative to late bilinguals in the same region. The inferior parietal cortex is a brain region highly associated with the language learning, which corresponds to the VBM result of the study.
Recent studies have also found that learning multiple languages not only re-structures the brain but also boosts brain's capacity for plasticity. A recent study found that multilingualism not only affects the grey matter but also white matter of the brain. White matter is made up of myelinated axons that is greatly associated with learning and communication. Neurolinguists used a diffusion tensor imaging (DTI) scanning method to determine the white matter intensity between monolinguals and bilinguals. Increased myelinations in white matter tracts were found in bilingual individuals who actively used both languages in everyday life. The demand of handling more than one language requires more efficient connectivity within the brain, which resulted in greater white matter density for multilinguals.
While it is still debated whether these changes in brain are result of genetic disposition or environmental demands, many evidences suggest that environmental, social experience in early multilinguals affect the structural and functional reorganization in the brain.
Novel treatments of depression
Historically, the monoamine imbalance hypothesis of depression played a dominant role in psychiatry and drug development. However, while traditional antidepressants cause a quick increase in noradrenaline, serotonin, or dopamine, there is a significant delay in their clinical effect and often an inadequate treatment response. As neuroscientists pursued this avenue of research, clinical and preclinical data across multiple modalities began to converge on pathways involved in neuroplasticity. They found a strong inverse relationship between the number of synapses and severity of depression symptoms and discovered that in addition to their neurotransmitter effect, traditional antidepressants improved neuroplasticity but over a significantly protracted time course of weeks or months. The search for faster acting antidepressants found success in the pursuit of ketamine, a well-known anesthetic agent, that was found to have potent anti-depressant effects after a single infusion due to its capacity to rapidly increase the number of dendritic spines and to restore aspects of functional connectivity. Additional neuroplasticity promoting compounds with therapeutic effects that were both rapid and enduring have been identified through classes of compounds including serotonergic psychedelics, cholinergicscopolamine, and other novel compounds. To differentiate between traditional antidepressants focused on monoamine modulation and this new category of fast acting antidepressants that achieve therapeutic effects through neuroplasticity, the term psychoplastogen was introduced. The development of non-hallucinogenic psychoplastogens such as zalsupindole, which are sometimes called neuroplastogens, has gained traction.
Nicotine
Nicotine affects the brain by binding to nicotinic acetylcholine receptors, the same receptors acetylcholine binds to, which has been linked with Neuroplasticity. Nicotine use may lower the rate of neuroplasticity in the brain by damaging the nicotinic-acetylcholine receptors needed to reuptake the acetylcholine necessary for neuroplasticity.
Theoretical Implications
Psychology and cognitive science
Evidence of neural plasticity has significantly influenced debates in psychology and cognitive science, particularly the longstanding dispute between empiricists and nativists regarding the nature of the human mind. Empiricists argue that the brain's capacity for reorganization demonstrates that cognitive capacities are largely a reflection of a learner's experience, challenging nativist claims that the mind has considerable innate structure. However, other researchers point to constrained plasticity — the finding that certain brain regions consistently take on the same functional roles even under dramatically different developmental conditions, and that some cognitive abilities may never fully recover following brain injury or disease — as evidence in favour of nativist accounts of innate core cognitive capacities, such as face recognition and the ability to understand people's mental states. According to this view, constrained plasticity reveals the operation of innate specialized mechanisms that guide neural development toward certain functional outcomes regardless of variation in experience.
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