Neuroplasticity, also known as neural plasticity, or brain plasticity, is the ability of
neural networks in the
brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...
to change through growth and reorganization. It is when the brain is rewired to function in some way that differs from how it previously functioned. These changes range from individual
neuron pathways making new connections, to systematic adjustments like
cortical remapping. Examples of neuroplasticity include circuit and network changes that result from
learning a new ability, environmental influences, practice, and
psychological stress.
Neuroplasticity was once thought by
neuroscientist
A neuroscientist (or neurobiologist) is a scientist who has specialised knowledge in neuroscience, a branch of biology that deals with the physiology, biochemistry, psychology, anatomy and molecular biology of neurons, neural circuits, and glial ...
s to manifest only during childhood, but research in the latter half of the 20th century showed that many aspects of the brain can be altered (or are "plastic") even through adulthood.
However, the developing brain exhibits a higher degree of plasticity than the adult brain.
Activity-dependent plasticity Activity-dependent plasticity is a form of functional and structural neuroplasticity that arises from the use of cognitive functions and personal experience; hence, it is the biological basis for learning and the formation of new memories. Activity- ...
can have significant implications for healthy development, learning,
memory
Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered ...
, and recovery from
brain damage.
History
Origin
The term ''plasticity'' was first applied to behavior in 1890 by
William James
William James (January 11, 1842 – August 26, 1910) was an American philosopher, historian, and psychologist, and the first educator to offer a psychology course in the United States.
James is considered to be a leading thinker of the lat ...
in ''
The Principles of Psychology
''The Principles of Psychology'' is an 1890 book about psychology by William James, an American philosopher and psychologist who trained to be a physician before going into psychology. There are four methods from James' book: stream of consciousne ...
''.
The first person to use the term ''neural plasticity'' appears to have been the Polish neuroscientist
Jerzy Konorski
Jerzy Konorski (1 December 1903 in Łódź, Congress Poland – 14 November 1973 in Warsaw, Polish People's Republic, Poland) was a Polish neurophysiologist who further developed the work of Ivan Pavlov by discovering secondary conditioned reflexes ...
.
One of the first experiments providing evidence for the neuroplasticity phenomenon was conducted in 1793 by Italian anatomist Michele Vicenzo 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
William James (January 11, 1842 – August 26, 1910) was an American philosopher, historian, and psychologist, and the first educator to offer a psychology course in the United States.
James is considered to be a leading thinker of the lat ...
in ''
The Principles of Psychology
''The Principles of Psychology'' is an 1890 book about psychology by William James, an American philosopher and psychologist who trained to be a physician before going into psychology. There are four methods from James' book: stream of consciousne ...
'', 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,
Santiago Ramón y Cajal
Santiago Ramón y Cajal (; 1 May 1852 – 17 October 1934) was a Spanish neuroscientist, pathologist, and histologist specializing in neuroanatomy and the central nervous system. He and Camillo Golgi received the Nobel Prize in Physiology or Me ...
, ''father of neuroscience'', used the term neuronal plasticity to describe nonpathological changes in the structure of adult brains. Based on his renowned
neuron doctrine
The neuron doctrine is the concept that the nervous system is made up of discrete individual cells, a discovery due to decisive neuro-anatomical work of Santiago Ramón y Cajal and later presented by, among others, H. Waldeyer-Hartz. The term '' ...
, 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.
He used the term plasticity in reference to his work on findings of degeneration and regeneration in the central nervous system after a person had reached adulthood, specifically. Many neuroscientists used the term plasticity only to explain the regenerative capacity of the peripheral nervous system, which Cajal's conceptual transfer of the term gave rise to a controversial discussion.
The term has since been broadly applied:
Research and discovery
In 1923,
Karl Lashley
Karl Spencer Lashley (June 7, 1890 – August 7, 1958) was a psychologist and behaviorist remembered for his contributions to the study of learning and memory. A ''Review of General Psychology'' survey, published in 2002, ranked Lashley as the 61 ...
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 took place, neuroscientists did not widely accept the idea of neuroplasticity.
In 1945,
Justo Gonzalo
Justo Gonzalo Rodríguez-Leal (Barcelona, Spain, March 2, 1910 – Madrid, Spain, September 28, 1986),
Spanish neuroscientist, after obtaining his bachelor's degree in medicine, he specialized in Austria and Germany (1933–35) with a grant from ...
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
.g., see pp 260–62 Vol. I (1945), p 696 Vol. II (1950) 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
Marian Cleeves Diamond (November 11, 1926 – July 25, 2017) was an American scientist and educator who is considered one of the founders of modern neuroscience. She and her team were the first to publish evidence that the brain can change with ...
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
Paul Bach-y-Rita (April 4, 1934 – November 20, 2006) was an American neuroscientist whose most notable work was in the field of neuroplasticity. Bach-y-Rita was one of the first to seriously study the idea of neuroplasticity (although it was fi ...
,
Michael Merzenich
Michael Matthias Merzenich ( ; born 1942 in Lebanon, Oregon) is an American neuroscientist and professor emeritus at the University of California, San Francisco. He took the sensory cortex maps developed by his predecessors (Archie Tunturi, Clint ...
along with
Jon Kaas
Jon Kaas is a professor at Vanderbilt University and a member of the United States National Academy of Sciences. He has made discoveries about the organization of the mammalian brain, including the description of many areas of the cerebral cortex ...
, as well as several others.
In the 1960s,
Paul Bach-y-Rita
Paul Bach-y-Rita (April 4, 1934 – November 20, 2006) was an American neuroscientist whose most notable work was in the field of neuroplasticity. Bach-y-Rita was one of the first to seriously study the idea of neuroplasticity (although it was fi ...
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 Sensory substitution is a change of the characteristics of one sensory modality into stimuli of another sensory modality.
A sensory substitution system consists of three parts: a sensor, a coupling system, and a stimulator. The sensor records stimu ...
.
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
Shepherd Ivory Franz (May 27, 1874 – October 14, 1933) was an American psychologist. He was the first chairman of the psychology department at the University of California, Los Angeles and served as president of the American Psychological Associa ...
did work in this area.
Eleanor Maguire
Eleanor Anne Maguire (born 27 March 1970) is an Irish neuroscientist. Since 2007, she has been Professor of Cognitive Neuroscience at University College London where she is also a Wellcome Trust Principal Research Fellow.
Early life and educat ...
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
Michael Matthias Merzenich ( ; born 1942 in Lebanon, Oregon) is an American neuroscientist and professor emeritus at the University of California, San Francisco. He took the sensory cortex maps developed by his predecessors (Archie Tunturi, Clint ...
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
David Hunter Hubel (February 27, 1926 – September 22, 2013) was a Canadian American neurophysiologist noted for his studies of the structure and function of the visual cortex. He was co-recipient with Torsten Wiesel of the 1981 Nobel Priz ...
and
Torsten Wiesel
Torsten Nils Wiesel (born 3 June 1924) is a Swedish neurophysiologist. With David H. Hubel, he received the 1981 Nobel Prize in Physiology or Medicine, for their discoveries concerning information processing in the visual system; the prize was ...
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
In developmental psychology and developmental biology, a critical period is a maturational stage in the lifespan of an organism during which the nervous system is especially sensitive to certain environmental stimuli. If, for some reason, the org ...
. 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
The Kavli Prize was established in 2005 as a joint venture of the Norwegian Academy of Science and Letters, the Norwegian Ministry of Education and Research, and the Kavli Foundation. It honors, supports, and recognizes scientists for outstan ...
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 process 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, and energy production via
mitochondria.
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 plasticity is often understood as the brain's ability to change its neuronal connections. New neurons are constantly produced and integrated into the central nervous system throughout the life span 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. This type of neuroplasticity often studies the effect of various internal or external stimuli on the brain's anatomical reorganization. The changes of
grey matter
Grey matter is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries. Grey matter is distingu ...
proportion or the synaptic strength in the brain are considered as examples of structural neuroplasticity. Structural neuroplasticity is currently investigated more within the field of neuroscience in current academia.
Functional neuroplasticity
Functional plasticity refers to brain's ability to alter and adapt the functional properties of neurons. The changes can occur in response to previous activity (
activity-dependent plasticity Activity-dependent plasticity is a form of functional and structural neuroplasticity that arises from the use of cognitive functions and personal experience; hence, it is the biological basis for learning and the formation of new memories. Activity- ...
) to acquire memory or 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
In neuroscience, synaptic plasticity is the ability of synapses to strengthen or weaken over time, in response to increases or decreases in their activity. Since memories are postulated to be represented by vastly interconnected neural circuits ...
. The strengthening or weakening of synapses that results in an increase or decrease of firing rate of the neurons are called
long-term potentiation
In neuroscience, long-term potentiation (LTP) is a persistent strengthening of synapses based on recent patterns of activity. These are patterns of synaptic activity that produce a long-lasting increase in signal transmission between two neurons ...
(LTP) and
long-term depression
In neurophysiology, long-term depression (LTD) is an activity-dependent reduction in the efficacy of neuronal synapses lasting hours or longer following a long patterned stimulus. LTD occurs in many areas of the CNS with varying mechanisms depen ...
(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 been 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
Ultrastructure (or ultra-structure) is the architecture of cells and biomaterials that is visible at higher magnifications than found on a standard optical light microscope. This traditionally meant the resolution and magnification range of a co ...
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
Neural Darwinism is a biological, and more specifically Darwinian and selectionist, approach to understanding global brain function, originally proposed by American biologist, researcher and Nobel-Prize recipient Gerald Maurice Edelman (July 1, ...
. 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
Classical conditioning (also known as Pavlovian or respondent conditioning) is a behavioral procedure in which a biologically potent stimulus (e.g. food) is paired with a previously neutral stimulus (e.g. a triangle). It also refers to the learni ...
in invertebrate animal models such as ''
Aplysia
''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are one clade of large sea slugs, marine gastropod mollusks.
These benthic herbivorous creatures can become rather large compared with most ...
''.
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
The hippocampus (via Latin from Greek , ' seahorse') is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, ...
and
olfactory bulb
The olfactory bulb (Latin: ''bulbus olfactorius'') is a neural structure of the vertebrate forebrain involved in olfaction, the sense of smell. It sends olfactory information to be further processed in the amygdala, the orbitofrontal cortex ( ...
, 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.
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
Acquired brain injury (ABI) is brain damage caused by events after birth, rather than as part of a genetic or congenital disorder such as fetal alcohol syndrome, perinatal illness or perinatal hypoxia. ABI can result in cognitive, physical, e ...
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
Constraint-induced movement therapy (CI, CIT, or CIMT) is a form of rehabilitation therapy that improves upper extremity function in stroke and other central nervous system damage patients by increasing the use of their affected upper limb. ,
functional electrical stimulation
Functional electrical stimulation (FES) is a technique that uses low-energy electrical pulses to artificially generate body movements in individuals who have been paralyzed due to injury to the central nervous system. More specifically, FES can ...
, treadmill training with body-weight support, and
virtual reality therapy
Virtual reality therapy (VRT), also known as virtual reality immersion therapy (VRIT), simulation for therapy (SFT), virtual reality exposure therapy (VRET), and computerized CBT (CCBT), is the use of virtual reality technology for psychological o ...
.
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
''The New England Journal of Medicine'' (''NEJM'') is a weekly medical journal published by the Massachusetts Medical Society. It is among the most prestigious peer-reviewed medical journals as well as the oldest continuously published one.
His ...
'' 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 biology, binocular vision is a type of vision in which an animal has two eyes capable of facing the same direction to perceive a single three-dimensional image of its surroundings. Binocular vision does not typically refer to vision where an ...
, in particular
stereopsis
Stereopsis () is the component of depth perception retrieved through binocular vision.
Stereopsis is not the only contributor to depth perception, but it is a major one. Binocular vision happens because each eye receives a different image becaus ...
, in early childhood or they would never gain it. In recent years, however, successful improvements in persons with
amblyopia,
convergence insufficiency
Convergence insufficiency is a sensory and neuromuscular anomaly of the binocular vision system, characterized by a reduced ability of the eyes to turn towards each other, or sustain convergence.
Symptoms
The symptoms and signs associated with con ...
or other stereo vision anomalies have become prime examples of neuroplasticity; binocular vision improvements and
stereopsis recovery
Stereopsis recovery, also recovery from stereoblindness, is the phenomenon of a stereoblind person gaining partial or full ability of stereo vision (stereopsis).
Recovering stereo vision as far as possible has long been established as an approach ...
are now active areas of scientific and clinical research.
Phantom limbs
![Mirror-box-comic](https://upload.wikimedia.org/wikipedia/commons/4/4a/Mirror-box-comic.jpg)
In the phenomenon of
phantom limb
A phantom limb is the sensation that an amputated or missing limb is still attached. Approximately 80 to 100% of individuals with an amputation experience sensations in their amputated limb. However, only a small percentage will experience pain ...
sensation, a person continues to feel pain or sensation within a part of their body that has been
amputated
Amputation is the removal of a limb by trauma, medical illness, or surgery. As a surgical measure, it is used to control pain or a disease process in the affected limb, such as malignancy or gangrene. In some cases, it is carried out on indiv ...
. This is strangely common, occurring in 60–80% of amputees. An
explanation
An explanation is a set of statements usually constructed to describe a set of facts which clarifies the causes, context, and consequences of those facts. It may establish rules or laws, and may clarify the existing rules or laws in relatio ...
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
In neuroanatomy, the postcentral gyrus is a prominent gyrus in the lateral parietal lobe of the human brain. It is the location of the primary somatosensory cortex, the main sensory receptive area for the sense of touch. Like other sensory areas, ...
. 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
Vilayanur Subramanian Ramachandran (born 10 August 1951) is an Indian-American neuroscientist. He is known for his wide-ranging experiments and theories in behavioral neurology, including the invention of the mirror box. Ramachandran is a disti ...
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. The authors stated that: "In fact, this finding extends our understanding of the brain's plasticity because it is evidence that profound changes in the mental representation of the body can be induced purely by internal brain mechanisms—the brain truly does change itself."
Chronic pain
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 A noxious stimulus is a stimulus strong enough to threaten the body’s integrity (i.e. cause damage to tissue). Noxious stimulation induces peripheral afferents responsible for transducing pain (including A-delta and C- nerve fibers, as well as f ...
and
inflammation
Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molec ...
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
Nociplastic pain or central sensitisation is a type of pain which is mechanically different from the normal nociceptive pain caused by inflammation and tissue damage or the neuropathic pain which results from nerve damage. It may occur in com ...
. 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
Grey matter is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries. Grey matter is distingu ...
in the brain globally, and more specifically at the
prefrontal cortex
In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46 ...
and right
thalamus
The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...
. 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
Carpal tunnel syndrome (CTS) is the collection of symptoms and signs associated with median neuropathy at the carpal tunnel. Most CTS is related to idiopathic
An idiopathic disease is any disease with an unknown cause or mechanism of apparen ...
.
Meditation
A number of studies have linked meditation practice to differences in cortical thickness or density of
gray matter
Grey matter is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries. Grey matter is distingui ...
. One of the most well-known studies to demonstrate this was led by
Sara Lazar, from Harvard University, in 2000.
Richard Davidson
Richard J. Davidson (born December 12, 1951) is professor of psychology and psychiatry at the University of Wisconsin–Madison as well as founder and chair of the Center for Healthy Minds and the affiliated non-profit Healthy Minds Innovations. ...
, a neuroscientist at the
University of Wisconsin
A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, ...
, has led experiments in collaboration with the
Dalai Lama
Dalai Lama (, ; ) is a title given by the Tibetan people to the foremost spiritual leader of the Gelug or "Yellow Hat" school of Tibetan Buddhism, the newest and most dominant of the four major schools of Tibetan Buddhism. The 14th and current D ...
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
Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil and includes feelings of dread over anticipated events. Anxiety is different than fear in that the former is defined as the anticipation of a future threat wh ...
,
depression,
fear
Fear is an intensely unpleasant emotion in response to perceiving or recognizing a danger or threat. Fear causes physiological changes that may produce behavioral reactions such as mounting an aggressive response or fleeing the threat. Fear ...
,
anger
Anger, also known as wrath or rage, is an intense emotional state involving a strong uncomfortable and non-cooperative response to a perceived provocation, hurt or threat.
A person experiencing anger will often experience physical effects, su ...
, and compassion as well as the ability of the body to heal itself.
Artistic Engagement & 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
VAGA is an artists collective dedicated to improving mental health and fighting cognitive decline through art therapy. The organisation brings together artists, clinicians and academic psychologists to foster research collaboration and the develop ...
, 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".
Fitness and exercise
Aerobic exercise increases the production of
neurotrophic factors
Neurotrophic factors (NTFs) are a family of biomolecules – nearly all of which are peptides or small proteins – that support the growth, survival, and differentiation of both developing and mature neurons. Most NTFs exert their trop ...
(compounds that promote growth or survival of neurons), such as
brain-derived neurotrophic factor
Brain-derived neurotrophic factor (BDNF), or abrineurin, is a protein found in the and the periphery. that, in humans, is encoded by the ''BDNF'' gene. BDNF is a member of the neurotrophin family of growth factors, which are related to the canon ...
(BDNF),
insulin-like growth factor 1
Insulin-like growth factor 1 (IGF-1), also called somatomedin C, is a hormone similar in molecular structure to insulin which plays an important role in childhood growth, and has anabolic effects in adults.
IGF-1 is a protein that in humans ...
(IGF-1), and
vascular endothelial growth factor
Vascular endothelial growth factor (VEGF, ), originally known as vascular permeability factor (VPF), is a signal protein produced by many cells that stimulates the formation of blood vessels. To be specific, VEGF is a sub-family of growth factors, ...
(VEGF).
Exercise-induced effects on the hippocampus are associated with measurable improvements in
spatial memory.
Consistent aerobic exercise over a period of several months induces marked
clinically significant improvements in
executive function
In cognitive science and neuropsychology, executive functions (collectively referred to as executive function and cognitive control) are a set of cognitive processes that are necessary for the cognitive control of behavior: selecting and succ ...
(i.e., the "
cognitive control
In cognitive science and neuropsychology, executive functions (collectively referred to as executive function and cognitive control) are a set of cognitive processes that are necessary for the cognitive control of behavior: selecting and suc ...
" of behavior) and increased
gray matter
Grey matter is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries. Grey matter is distingui ...
volume in multiple brain regions, particularly those that give rise to cognitive control.
The brain structures that show the greatest improvements in gray matter volume in response to aerobic exercise are the
prefrontal cortex
In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46 ...
and
hippocampus
The hippocampus (via Latin from Greek , ' seahorse') is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, ...
;
moderate improvements are seen in the
anterior cingulate cortex
In the human brain
The human brain is the central organ (anatomy), organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It c ...
,
parietal cortex
The parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus.
The parietal lobe integrates sensory inform ...
,
cerebellum,
caudate nucleus
The caudate nucleus is one of the structures that make up the corpus striatum, which is a component of the basal ganglia in the human brain. While the caudate nucleus has long been associated with motor processes due to its role in Parkinson's d ...
, and
nucleus accumbens
The nucleus accumbens (NAc or NAcc; also known as the accumbens nucleus, or formerly as the ''nucleus accumbens septi'', Latin for " nucleus adjacent to the septum") is a region in the basal forebrain rostral to the preoptic area of the hypot ...
.
Higher
physical fitness scores (measured by
VO2 max) are associated with better executive function, faster processing speed, and greater volume of the hippocampus, caudate nucleus, and nucleus accumbens.
Deafness and loss of hearing
Due to hearing loss, the
auditory cortex
The auditory cortex is the part of the temporal lobe that processes auditory information in humans and many other vertebrates. It is a part of the auditory system, performing basic and higher functions in hearing, such as possible relations to ...
and other association areas of the brain in deaf and/or hard of hearing people undergo compensatory plasticity.
The auditory cortex is usually reserved for processing auditory information in hearing people now is redirected to serve other functions, especially for
vision
Vision, Visions, or The Vision may refer to:
Perception Optical perception
* Visual perception, the sense of sight
* Visual system, the physical mechanism of eyesight
* Computer vision, a field dealing with how computers can be made to gain und ...
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
The auditory cortex is the part of the temporal lobe that processes auditory information in humans and many other vertebrates. It is a part of the auditory system, performing basic and higher functions in hearing, such as possible relations to ...
,
posterior parietal association cortex (PPAC), and
anterior cingulate cortex
In the human brain
The human brain is the central organ (anatomy), organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It c ...
(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 implant
A cochlear implant (CI) is a surgically implanted neuroprosthesis that provides a person who has moderate-to-profound sensorineural hearing loss with sound perception. With the help of therapy, cochlear implants may allow for improved speech unde ...
ation, as a rule, allows the children to learn the mother language and acquire acoustic communication.
Blindness
Due to vision loss, the
visual cortex
The visual cortex of the brain is the area of the cerebral cortex that processes visual information. It is located in the occipital lobe. Sensory input originating from the eyes travels through the lateral geniculate nucleus in the thalamus and ...
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
Human echolocation is the ability of humans to detect objects in their environment by sensing echoes from those objects, by actively creating sounds: for example, by tapping their canes, lightly stomping their foot, snapping their fingers, or maki ...
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.
Attention deficit hyperactivity disorder
MRI
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...
studies of 1713 participants shows that both children and adults with
attention deficit hyperactivity disorder
Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by excessive amounts of inattention, hyperactivity, and impulsivity that are pervasive, impairing in multiple contexts, and otherwise age-inap ...
(ADHD) have smaller volumes of the
nucleus accumbens
The nucleus accumbens (NAc or NAcc; also known as the accumbens nucleus, or formerly as the ''nucleus accumbens septi'', Latin for " nucleus adjacent to the septum") is a region in the basal forebrain rostral to the preoptic area of the hypot ...
,
amygdala
The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex verte ...
,
caudate,
hippocampus
The hippocampus (via Latin from Greek , ' seahorse') is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, ...
,
putamen
The putamen (; from Latin, meaning "nutshell") is a round structure located at the base of the forebrain (telencephalon). The putamen and caudate nucleus together form the dorsal striatum. It is also one of the structures that compose the basal ...
, and overall cortical and intracranial volume; and have less surface area and cortical thickness, compared to people without ADHD. Brain volume does not correlate to intelligence, or intelligence quotient (IQ). People with ADHD exhibit atypical neuroconnectivity. In particular, it has been hypothesized that ADHD symptomatology may arise from a deviation from neurotypical synchronization and interaction within and between these large-scale networks during brain development. Investigating functional connectivity using the sub-second temporal resolution of electroencephalography (EEG) instead allows for the measurement of a wider range of brain oscillatory phenomena, including transient changes in connectivity during cognition and behavior.
Reviews of
MRI
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...
and electroencephalography (EEG) studies on individuals with
ADHD suggest that the long-term treatment of ADHD with stimulants, such as
amphetamine or
methylphenidate
Methylphenidate, sold under the brand names Ritalin and Concerta among others, is the most widely prescribed central nervous system (CNS) stimulant medication used to treat attention deficit hyperactivity disorder (ADHD) and, to a lesser exten ...
, 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
The caudate nucleus is one of the structures that make up the corpus striatum, which is a component of the basal ganglia in the human brain. While the caudate nucleus has long been associated with motor processes due to its role in Parkinson's d ...
of the
basal ganglia
The basal ganglia (BG), or basal nuclei, are a group of subcortical nuclei, of varied origin, in the brains of vertebrates. In humans, and some primates, there are some differences, mainly in the division of the globus pallidus into an exter ...
, left
ventrolateral prefrontal cortex (VLPFC), and
superior temporal gyrus.
In early child development
Neuroplasticity is most active in childhood as a part of normal
human development Human development may refer to:
* Development of the human body
* Developmental psychology
* Human development (economics)
* Human Development Index, an index used to rank countries by level of human development
* Human evolution
Human evoluti ...
, 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 animals
In a single
lifespan, individuals of an animal
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
may encounter various changes in brain
morphology
Morphology, from the Greek and meaning "study of shape", may refer to:
Disciplines
* Morphology (archaeology), study of the shapes or forms of artifacts
* Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...
. Many of these differences are caused by the release of
hormones in the brain; others are the product of
evolutionary factors or
developmental stages Stages of development may refer to:
Biology
*Developmental biology, the study of the process by which animals and plants grow and develop
*Prenatal development, also called fetal development, or embryology
*Human development (biology), the proc ...
.
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
Volume is a measure of occupied three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch). Th ...
of their
hippocampus
The hippocampus (via Latin from Greek , ' seahorse') is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, ...
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
A songbird is a bird belonging to the suborder Passeri of the perching birds (Passeriformes). Another name that is sometimes seen as the scientific or vernacular name is Oscines, from Latin ''oscen'', "songbird". The Passeriformes contains 5 ...
, 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
Gonadotropin-releasing hormone (GnRH) is a releasing hormone responsible for the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. GnRH is a tropic peptide hormone synthesized and release ...
(GnRH)
immunoreactivity
An immunoassay (IA) is a biochemical test that measures the presence or concentration of a macromolecule or a small molecule in a solution through the use of an antibody (usually) or an antigen (sometimes). The molecule detected by the immunoassay ...
, 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
Inhibitor or inhibition may refer to:
In biology
* Enzyme inhibitor, a substance that binds to an enzyme and decreases the enzyme's activity
* Reuptake inhibitor, a substance that increases neurotransmission by blocking the reuptake of a neurotra ...
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
The Japanese common toad, Japanese warty toad or Japanese toad (''Bufo japonicus'') is a species of toad in the family Bufonidae. It is endemic to Japan. Its natural habitats are subarctic forests, temperate forests, temperate shrubland, swamps, f ...
, part of the
amygdala
The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex verte ...
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
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
experience a change in the "size of the hypothalamic
suprachiasmatic nucleus and
vasopressin
Human vasopressin, also called antidiuretic hormone (ADH), arginine vasopressin (AVP) or argipressin, is a hormone synthesized from the AVP gene as a peptide prohormone in neurons in the hypothalamus, and is converted to AVP. It then trave ...
-immunoreactive neurons within it"
during the fall, when these parts are larger. In the spring, both reduce in size.
Traumatic brain injury research
Randy Nudo's group 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. Nudo is also involved in studying the treatment plans that may enhance recovery from strokes, such as physiotherapy,
pharmacotherapy
Pharmacotherapy is therapy using pharmaceutical drugs, as distinguished from therapy using surgery (surgical therapy), radiation (radiation therapy), movement (physical therapy), or other modes. Among physicians, sometimes the term ''medical ther ...
, and electrical-stimulation therapy.
Jon Kaas
Jon Kaas is a professor at Vanderbilt University and a member of the United States National Academy of Sciences. He has made discoveries about the organization of the mammalian brain, including the description of many areas of the cerebral cortex ...
, a professor at
Vanderbilt University
Vanderbilt University (informally Vandy or VU) is a private research university in Nashville, Tennessee. Founded in 1873, it was named in honor of shipping and rail magnate Cornelius Vanderbilt, who provided the school its initial $1-million ...
, 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
Emory University is a private research university in Atlanta, Georgia. Founded in 1836 as "Emory College" by the Methodist Episcopal Church and named in honor of Methodist bishop John Emory, Emory is the second-oldest private institution of ...
, specifically Dr.
Donald Stein
Donald is a masculine given name derived from the Gaelic name ''Dòmhnall''.. This comes from the Proto-Celtic *''Dumno-ualos'' ("world-ruler" or "world-wielder"). The final -''d'' in ''Donald'' is partly derived from a misinterpretation of the ...
and Dr. 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.
Dr. Stein noticed that female mice seemed to recover from brain injuries better than male mice, and that at certain points in the
estrus cycle
The estrous cycle (, originally ) is the set of recurring physiological changes that are induced by reproductive hormones in most mammalian therian females. Estrous cycles start after sexual maturity in females and are interrupted by anestrous p ...
, 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
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
s with reduced expression after age 40, and especially after age 70.
Genes that play central roles in
synaptic plasticity
In neuroscience, synaptic plasticity is the ability of synapses to strengthen or weaken over time, in response to increases or decreases in their activity. Since memories are postulated to be represented by vastly interconnected neural circuits ...
were the most significantly affected by age, generally showing reduced expression over time. There was also a marked increase in cortical
DNA damage
DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as radiation can cause DNA d ...
, likely
oxidative DNA damage, in
gene promoters with aging.
Reactive oxygen species
In chemistry, reactive oxygen species (ROS) are highly reactive chemicals formed from diatomic oxygen (). Examples of ROS include peroxides, superoxide, hydroxyl radical, singlet oxygen, and alpha-oxygen.
The reduction of molecular oxygen () p ...
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
The beneficial effect of multilingualism on people's behavior and cognition is well-known nowadays. 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
Voxel-based morphometry is a computational approach to neuroanatomy that measures differences in local concentrations of brain tissue, through a voxel-wise comparison of multiple brain images.
In traditional morphometry, volume of the whole br ...
(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
White matter refers to areas of the central nervous system (CNS) that are mainly made up of myelinated axons, also called tracts. Long thought to be passive tissue, white matter affects learning and brain functions, modulating the distributi ...
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 the elevated NE, 5HT, or DA elicited by traditional antidepressants is quick, there is a significant delay in clinical efficacy and often 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 with 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
Ketamine is a dissociative anesthetic used medically for induction and maintenance of anesthesia. It is also used as a recreational drug. It is one of the safest anesthetics, as, in contrast with opiates, ether, and propofol, it suppresses ...
, 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,
cholinergic
Cholinergic agents are compounds which mimic the action of acetylcholine and/or butyrylcholine. In general, the word " choline" describes the various quaternary ammonium salts containing the ''N'',''N'',''N''-trimethylethanolammonium cati ...
scopolamine, 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.
See also
*
Activity-dependent plasticity Activity-dependent plasticity is a form of functional and structural neuroplasticity that arises from the use of cognitive functions and personal experience; hence, it is the biological basis for learning and the formation of new memories. Activity- ...
*
Brain training
Brain training (also called cognitive training) is a program of regular activities purported to maintain or improve one's cognitive abilities. The phrase “cognitive ability” usually refers to components of fluid intelligence such as executiv ...
*
Environmental enrichment (neural)
Environmental enrichment is the stimulation of the brain by its physical and social surroundings. Brains in richer, more stimulating environments have higher rates of synaptogenesis and more complex dendrite arbors, leading to increased brain ac ...
*
Neural backpropagation
Neural backpropagation is the phenomenon in which, after the action potential of a neuron creates a voltage spike down the axon (normal propagation), another impulse is generated from the Soma (biology), soma and propagates towards the Apical den ...
*
Neuroplastic effects of pollution
*
Psychoplastogen
*
Psychedelic drug
*
Kinesiology
Kinesiology () is the scientific study of human body movement. Kinesiology addresses physiological, anatomical, biomechanical, pathological, neuropsychological principles and mechanisms of movement. Applications of kinesiology to human healt ...
References
Further reading
*
*Edelman, Gerald. Bright Air, Brilliant Fire: On the Matter of the Mind (Basic Books, 1992, Reprint edition 1993).
*Edelman and Jean-Pierre Changeux, editors, The Brain (Transaction Publishers, 2000).
*
*
*
*
*
*
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*
*
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*
;Videos
* about consciousness, mirror neurons, and phantom limb syndrome
;Other readings
*
External links
*
Neuro Myths: Separating Fact and Fiction in Brain-Based Learningby Sara Bernard
{{Authority control
Memory
Neurophysiology
Neurotrauma
Neural circuits
Brain