Neuroplasticity challenges the idea that brain functions are fixed in certain locations.

Neuroplasticity (variously referred to as brain plasticity or cortical plasticity or cortical re-mapping) refers to the changes that occur in the organization of the brain as a result of experience. The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain A surprising consequence of neuroplasticity is that the brain activity associated with a given function can move to a different location as a consequence of normal experience or brain damage/recovery.

The concept of neuroplasticity pushes the boundaries of the brain areas that are still re-wiring in response to changes in environment. Several decades ago, the consensus was that lower brain and neocortical areas were immutable after development, whereas areas related to memory formation, such as the hippocampus and dentate gyrus, where new neurons continue to be produced into adulthood, were highly plastic. The hippocampus is a part of the Forebrain, located in the medial Temporal lobe. The dentate gyrus is part of the Hippocampal formation. It is thought to contribute to new memories as well as other functional roles ^[1] Hubel and Wiesel had demonstrated that ocular dominance columns in the lowest neocortical visual area, V1, were largely immutable after the critical period in development. David Hunter Hubel (born February 27, 1926) was co-recipient with Torsten Wiesel of the 1981 Nobel Prize in Physiology or Medicine, for their Torsten Nils Wiesel (b June 3, 1924) was a Swedish co-recipient with David H This article is about a critical period in an organism's development ^[2] Critical periods also were studied for language and suggested it was likely that the sensory pathways were fixed after their respective critical periods. Environmental changes could cause changes in behavior and cognition by modifying the connections of the new neurons in the hippocampus.

Decades of research have now shown that substantial changes occur in the lowest neocortical processing areas, and that these changes can profoundly alter the pattern of neuronal activation in response to experience. According to the theory of neuroplasticity, thinking, learning, and acting actually change both the brain's functional anatomy from top to bottom, and its physical anatomy. Anatomy (from the Greek anatomia, from ana separate apart from and temnein, to cut up cut open is a branch of Biology that is the consideration A proper reconciliation of critical period studies, which demonstrate some functional and anatomical aspects of the neocortex are largely immutable after development, with the new findings on neuroplasticity, which demonstrate some functional aspects are highly mutable, are an active area of current research.

Canadian psychiatrist Norman Doidge has called neuroplasticity "one of the most extraordinary discoveries of the twentieth century. "^[3]

Brain plasticity and cortical maps

Cortical organization, especially for the sensory systems, is often described in terms of maps. See also Sense A sensory system is a part of the Nervous system responsible for processing sensory information Cortical maps are collections (areas of minicolumns in the Brain cortex that have been identified as performing a specific information processing function ^[4] For example, sensory information from the foot projects to one cortical site and the projections from the hand target in another site. As the result of this somatotopic organization of sensory inputs to the cortex, cortical representation of the body resembles a map (or homunculus). The concept of a homunculus ( Latin for "little man" plural "homunculi" the diminutive of homo, "man" is often used to illustrate

In the late 1970s and early 1980s, several groups began exploring the impacts of removing portions of the sensory inputs. In Psychology, sensation is the first stage in the biochemical and neurologic events that begins with the impinging of a stimulus upon the receptor cells of a Michael Merzenich and Jon Kaas used the cortical map as their dependent variable. Michael M Merzenich is a professor emeritus Neuroscientist at the University of California San Francisco. Jon Kaas is a Professor in Vanderbilt University and a member of the United States National Academy of Sciences. They found—and this has been since corroborated by a wide range of labs—that if the cortical map is deprived of its input it will become activated at a later time in response to other, usually adjacent inputs. At least in the somatic sensory system, in which this phenomenon has been most thoroughly investigated, JT Wall and J Xu have traced the mechanisms underlying this plasticity. Re-organization occurs at every level in the processing hierarchy to result in the map changes observed in the cerebral cortex. ^[5] It is not cortically emergent. For other uses see Emergence (disambiguation, Emergent, and Emergency.

Merzenich and William Jenkins (1990) initiated studies relating sensory experience, without pathological perturbation, to cortically observed plasticity in the primate somatosensory system, with the finding that sensory sites activated in an attended operant behavior increase in their cortical representation. A primate is a member of the biological order Primates ( Latin: "prime first rank" the group that contains Lemurs the Aye-aye Operant Behavior is the network of factors and events involved in the behavior of human and non-human animals Shortly thereafter, Ford Ebner and colleagues (1994) made similar efforts in the rodent whisker barrel (also somatic sensory system). Rodentia is an order of Mammals also known as rodents, characterised by two continuously-growing incisors in the upper and lower jaws which must These two groups largely diverged over the years. The rodent whisker barrel efforts became a focus for Ebner, Matthew Diamond, Michael Armstrong-James, Robert Sachdev, Kevin Fox, and Dan Feldman, and great inroads were made in identifying the locus of change as being at cortical synapses expressing NMDA receptors, and in implicating cholinergic inputs as necessary for normal expression. Chemical synapses are specialized junctions through which Neurons signal to each other and to non-neuronal cells such as those in Muscles or Glands Gene expression is the process by which inheritable information from a Gene, such as the DNA sequence, is made into a functional Gene product, such The NMDA receptor ( NMDAR) is an Ionotropic receptor for Glutamate ( NMDA ( N -methyl D -aspartate is a name of its selective A receptor is cholinergic if it uses Acetylcholine as its Neurotransmitter. However, the rodent studies were poorly focused on the behavioral end, and Ron Frostig and Daniel Polley (1999, 2004) identified behavioral manipulations as causing a substantial impact on the cortical plasticity in that system. Behavior or behaviour (see spelling differences) refers to the actions or Reactions of an object or Organism, usually

Merzenich and DT Blake (2002, 2005, 2006) went on to use cortical implants to study the evolution of plasticity in both the somatosensory and auditory systems. Michael M Merzenich is a professor emeritus Neuroscientist at the University of California San Francisco. Both systems show similar changes with respect to behavior. Behavior or behaviour (see spelling differences) refers to the actions or Reactions of an object or Organism, usually When a stimulus is cognitively associated with reinforcement, its cortical representation is strengthened and enlarged. In Operant conditioning, reinforcement is an immediate increase in the strength of a response following a change in environment In some cases, cortical representations can increase two to three fold in 1-2 days at the time at which a new sensory motor behavior is first acquired, and changes are largely finished within at most a few weeks. Control studies show that these changes are not caused by sensory experience alone: they require learning about the sensory experience, and are strongest for the stimuli that are associated with reward, and occur with equal ease in operant and classical conditioning behaviors.

An interesting phenomenon involving cortical maps is the incidence of phantom limbs. A phantom limb is the sensation that an amputated or missing limb (even an organ like the appendix is still attached to the body and is moving appropriately This is most commonly described in people that have undergone amputations in hands, arms, and legs, but it is not limited to extremities. Amputation is the removal of a body extremity by trauma or Surgery. The phantom limb feeling, which is thought to result from disorganization in the homunculus and the inability to receive input from the targeted area, may be annoying or painful. IF YOU ARE EDITING THIS ARTICLE TO LET US KNOW THAT YOUR FRIEND WHAT'S-HIS-OR-HER-NAME IS THE MOST ANNOYING PERSON IN THE WORLD PLEASE KNOW THE YOU ARE ABOUT THE BILLIONTH CLEVER GUY TO Pain, in the sense of physical pain, is a typical sensory experience that may be described as the unpleasant awareness of a noxious stimulus or bodily harm Incidentally, it is more common after unexpected losses than planned amputations. There is a high correlation with the extent of physical remapping and the extent of phantom pain. In Probability theory and Statistics, correlation, (often measured as a correlation coefficient) indicates the strength and direction of a linear As it fades, it is a fascinating functional example of new neural connections in the human adult brain.

The concept of plasticity can be applied to molecular as well as to environmental events. The phenomenon itself is complex and can involve many levels of organization. To some extent the term itself has lost its explanatory value because almost any changes in brain activity can be attributed to some sort of "plasticity".

For example, the term is used prevalently in studies of axon guidance during development, short-term visual adaptation to motion or contours, maturation of cortical maps, recovery after amputation or stroke, and changes that occur in normal learning in the adult. Some authors separate forms into adaptations that have positive or negative consequences for the animal. For example, if an organism, after a stroke, can recover to normal levels of performance, that adaptiveness could be considered an example of "positive plasticity". An excessive level of neuronal growth leading to spasticity or tonic paralysis, or an excessive release of neurotransmitters in response to injury which could kill nerve cells, would have to be considered perhaps as a "negative or maladaptive" plasticity. Spasticity or muscular hypertonicity is a disorder of the body Motor system, and especially the central nervous system (CNS in which certain Muscles continually Paralysed redirects here For other uses see xx Paralysed (disambiguation Paralysis is the complete loss of Muscle function See Chemical synapse for an introduction to concepts and terminology used in this article

Treatment of brain damage

Neuroplasticity is a 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. A neurological condition Acquired Brain Injury ( ABI) is damage to the brain acquired after birth Rehabilitation of sensory and Cognitive function typically involves methods for retraining Neural pathways or training new neural pathways to regain or improve neurocognitive

The adult brain is not "hard-wired" with fixed and immutable neuronal circuits. To execute instructions a Computer 's Processor must generate the control signals used to perform the processor's actions in the proper sequence In Neuroscience, a neural network describes a population of physically interconnected Neurons or a group of disparate neurons whose inputs or signalling targets define 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 solid evidence that neurogenesis, the formation of new nerve cells, occurs in the adult, mammalian brain--and such changes can persist well into old age. Neurogenesis ( birth of Neurons ' is the process by which neurons are created ^[6] The evidence for neurogenesis is restricted to the hippocampus and olfactory bulb. The hippocampus is a part of the Forebrain, located in the medial Temporal lobe. The olfactory bulb is a structure of the Vertebrate Forebrain involved in Olfaction, the perception of Odors. In the rest of the brain, neurons can die, but they cannot be created. However, there is now 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 manner in which 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 epistemology referred to as Neural Darwinism and developed by immunologist Nobel laureate Gerald Edelman. Neural Darwinism, a large scale theory of brain function by Gerald Edelman, was initially published in 1978 in a book called The Mindful Brain (MIT Press Gerald Maurice Edelman (born July 1, 1929) is an American biologist who won the 1972 Nobel Prize in Physiology or Medicine for his 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. Classical Conditioning (also Pavlovian or Respondent Conditioning) is a form of Associative learning that was first demonstrated by Ivan Pavlov This latter program of neuroscience research has emanated from the ground-breaking work of another Nobel laureate, Eric Kandel, and his colleagues at Columbia University College of Physicians and Surgeons. Eric Richard Kandel (born November 7, 1929) is a Psychiatrist, a neuroscientist and Professor of Biochemistry Columbia University College of Physicians and Surgeons, abbreviated P&S, is a graduate school of Columbia University located on the health sciences campus in the

Brain plasticity during operation of brain-machine interfaces

Brain-machine interface (BMI) is a rapidly developing field of neuroscience. A brain-computer interface (BCI sometimes called a direct neural interface or a brain-machine interface, is a direct communication pathway between a human or animal A brain-computer interface (BCI sometimes called a direct neural interface or a brain-machine interface, is a direct communication pathway between a human or animal Neuroscience is a field devoted to the scientific study of the nervous system According to the results obtained by Mikhail Lebedev, Miguel Nicolelis and their colleagues (Lebedev et al. 2005), operation of BMIs results in incorporation of artificial actuators into brain representations. Miguel Angelo Laporta Nicolelis, MD PhD ( São Paulo, March 7, 1961) is a Brazilian Physician and Scientist, best known The scientists showed that modifications in neuronal representation of the monkey's hand and the actuator that was controlled by the monkey brain occurred in multiple cortical areas while the monkey operated a BMI. In these single day experiments, monkeys initially moved the actuator by pushing a joystick. After mapping out the motor neuron ensembles, control of the actuator was switched to the model of the ensembles so that the brain activity, and not the hand, directly controlled the actuator. The activity of individual neurons and neuronal populations became less representative of the animal's hand movements while representing the movements of the actuator. Presumably as a result of this adaptation, the animals could eventually stop moving their hands yet continue to operate the actuator. Thus, during BMI control, cortical ensembles plastically adapt, within tens of minutes, to represent behaviorally significant motor parameters, even if these are not associated with movements of the animal's own limb.

Active laboratory groups include those of John Donoghue at Brown, Richard Andersen at Caltech, Krishna Shenoy at Stanford, Nicholas Hatsopoulos of University of Chicago, Andy Schwartz at Pitt, Sandro Mussa-Ivaldi at Northwestern and Miguel Nicolelis at Duke. The University of Pittsburgh, commonly referred to as Pitt, is a non-sectarian coeducational independent state-related, "public" research University Miguel Angelo Laporta Nicolelis, MD PhD ( São Paulo, March 7, 1961) is a Brazilian Physician and Scientist, best known Donoghue and Nicolelis' groups have independently shown that animals can control external interfaces in tasks requiring feedback, with models based on activity of cortical neurons, and that animals can adaptively change their minds to make the models work better. Donoghue's group took the implants from Richard Normann's lab at Utah (the "Utah" array), and improved it by changing the insulation from polyimide to parylene-c, and commercialized it through the company Cyberkinetics. Cyberkinetics is an American company It was cofounded by John Donoghue Mijail Serruya and Gerhard Friehs of Brown University and Nicho Hatsopoulos of the University These efforts are the leading candidate for the first human trials on a broad scale for motor cortical implants to help quadriplegic or trapped patients communicate with the outside world.

Thought and neuroplasticity

The Dalai Lama invited Richard Davidson, a Harvard-trained neuroscientist at the University of Wisconsin-Madison's W. The Dalai Lama is the spiritual and political leader of the Tibetan people according to Tibetan Buddhism. Richard J Davidson is a scientist at the University of Wisconsin-Madison. M. Keck Laboratory for Functional Brain Imaging and Behavior to his home in Dharamsala, India, in 1992 after learning about Davidson's innovative research into the neuroscience of emotions. Could the simple act of thinking change the brain? Most scientists believed this idea to be false, but they agreed to test the theory. One such experiment involved a group of eight Buddhist monk adepts and ten volunteers who had been trained in meditation for one week in Davidson's lab. Buddhism is a family of beliefs and practices Meditation is a mental discipline by which one attempts to get beyond the conditioned "thinking" mind into a deeper state of relaxation or awareness All the people tested were told to meditate on compassion and love. Two of the controls, and all of the monks, experienced an increase in the number of gamma waves in their brain during meditation. A gamma wave is a pattern of brain waves associated with Perception and Consciousness. As soon as they stopped meditating, the volunteers' gamma wave production returned to normal, while the monks, who had meditated on compassion for more than 10,000 hours in order to attain the rank of adept, did not experience a decrease to normal in the gamma wave production after they stopped meditating. The synchronized gamma wave area of the monks' brains during meditation on love and compassion was found to be larger than that corresponding activation of the volunteers' brains. Davidson's results were published in the Proceedings of the National Academy of Sciences in November, 2004 and TIME recognized Davidson as one of the ten most influential people in 2006 on the basis of his research. ^[7][8]

See also

• Tetris effect
• Eric Kandel

Notes

Further reading

• Donoghue JP, "Connecting cortex to machines: recent advances in brain interfaces. " Nat Neurosci. , 2002 Nov;5 Suppl:1085-8.
• Flor, H. (2002). "Phantom limb pain: Characteristics, causes, and treatments. " Lancet Neurology, 1: 182-189.
• Lebedev, M. A. , Carmena, J. M. , O’Doherty, J. E. , Zacksenhouse, M. , Henriquez, C. S. , Principe, J. C. , Nicolelis, M. A. L. (2005), Cortical ensemble adaptation to represent actuators controlled by a brain-machine interface. J. Neurosci. 25: 4681-4693
• Ramachandran & Hirstein (1998). "The perception of phantom limbs", Brain, 121: 1603-1630. In Psychology and the Cognitive sciences perception is the process of attaining awareness or understanding of sensory Information.
• Meditation Alters Brain Structure, from a University of Wisconsin-Madison website
• The Brain: Malleable, Capable, Vulnerable, from a May 2007 article in The New York Times
• Monkeys Treat Robot Arm as Their Own from betterhumans. com
• Monkey See, Robotics Do from medicinenet. com
• Richard Davidson and Daniel Goleman Dialogue - Training the Brain: Cultivating Emotional Skills [1]