User:Jhbuk/Sandbox

Neuroplasticity is one of the most important and developing topics in Neuroscience today. Dr. Donald Stein, who wrote one of the first books on brain plasticity, Brain Injury and Recovery, defined “Brain plasticity as the ability for the organism to adapt to the changes in its environment in a positive and adaptive way because it’s not just enough to change…”[14] Norman Doidge’s book, The Brain that Changes Itself has ample examples of plasticity. There have been several pioneers through this idea of neuroplasticity. Between 30 to 40 years ago there was a notion that each point on the body directly correlates with a specific point on the ‘brain map,’ essentially, “anatomically hard-wired at birth.”[5] There was no hope for people suffering from a brain injury according to the doctors that believed the hardwired system. A few key scientists did not believe in this doctrine and proceeded to seek another answer.

Paul Bach-y-Rita

Paul Bach-y-Rita, deceased in 2006, was the “father of sensory substitution and brain plasticity.”[12] In working with a patient whose vestibular system had been damaged he developed BrainPort, a machine that “replaces her vestibular apparatus and [will] send balance signals to her brain from her tongue.”[5] After she had used this machine for some time it was no longer necessary, as she regained the ability to function normally. Her balancing act days were over. Plasticity is the major explanation for the phenomena. Because her vestibular system was “disorganized” and sending random rather than coherent signals, the apparatus found new pathways around the damaged or blocked neural pathways, helping to reinforce the signals that were sent by remaining healthy tissues. Bach-y-Rita explained plasticity by saying, “If you are driving from here to Milwaukee and the main bridge goes out, first you are paralyzed. Then you take old secondary roads through the farmland. Then you use these roads more; you find shorter paths to use to get where you want to go, and you start to get there faster. These “secondary” neural pathways are “unmasked” or exposed and strengthened as they are used. The “unmasking” process is generally thought to be one of the principal ways in which the plastic brain reorganizes itself.”[5]

In addition to helping patients with their balance problems, Bach y Rita invented a device that allowed blind people to read, perceive shadows, and distinguish between close and distant objects. This “machine was one of the first and boldest applications of neuroplasticity.”[5] The patient sat in an electrically stimulated chair that had a large camera behind it which scanned the area, sending electrical signals of the image to four hundred vibrating stimulators on the chair against the patient’s skin. The six subjects of the experiment were eventually able to recognize a picture of the supermodel Twiggy.[5] It must be emphasized that these people were congenitally blind and had previously not been able to see. Bach-y-Rita believed in sensory substitution; if one sense is damaged, your other senses can sometimes take over. He thought skin and its touch receptors could act as a retina (using one sense for another). In order for the brain to interpret tactile information and convert it into visual information, it has to learn something new and adapt to the new signals. The brain's capacity to adapt implied that it possessed plasticity. He thought, “We see with our brains, not with our eyes.”[5]

A tragic stroke that left his father paralyzed inspired Bach-y-Rita to study brain rehabilitation. His brother, a physician, worked tirelessly to develop therapeutic measures which were so successful that the father recovered complete functionality by age 68 and was able to live a normal, active life which even included mountain climbing. “His father’s story was firsthand evidence that a ‘late recovery’ could occur even with a massive lesion in an elderly person.”[5] He found more evidence of this possible brain reorganization with Shepherd Ivory Franz’s work. One study involved stroke patients who were able to recover through the use of brain stimulating exercises after having been paralyzed for years. “Franz understood the importance of interesting, motivating rehabilitation: ‘Under conditions of interest, such as that of competition, the resulting movement may be much more efficiently carried out than in the dull, routine training in the laboratory’(Franz, 1921, pg.93).”^[1] This notion has led to motivational rehabilitation programs that are used today.

Michael Merzenich

Michael Merzenich is a neuroscientist who has been one of the pioneers of brain plasticity 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.”[5] 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.”[5] This implied brain plasticity during the critical period. However, Merzenich argued that brain plasticity 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 was 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.”[5]

Early in his career Merzenich collaborated with a group of people to develop the cochlear implant, which allows congenitally deaf people to hear. He also developed a series of “plasticity-based computer programs known as Fast ForWord .” FastForWord offers seven brain exercises to help with the language and learning deficits of dyslexia. In a recent study, experimental training was done in adults to see if it would help to counteract the negative plasticity that results from age-related cognitive decline (ARCD). The ET design included six exercises designed to reverse the dysfunctions caused by ARCD in cognition, memory, motor control, and so on [9]. After use of the ET program for 8–10 weeks, there was a “significant increase in task-specific performance.”[9] The data collected from the study indicated that a brain plasticity-based program could notably improve cognitive function and memory in adults with ARCD.

Vilanyanur S. Ramachandran

Among his many other accomplishments in neuroscience, Vilayanur S. Ramachandran is famous for his work regarding phantom limbs, or “…the vivid impression that the limb is not only still present but also painful,”^[2] which is called Phantom limb syndrome [1]. This phenomenon arises from tragic limb loss through accident, amputation or other means. Those who suffer from this syndrome experience painful sensations in their stumps described as feeling like spasmodic clenching of the hands caused by “nails digging into my palm.”^[2] A possible explanation for this is that the brain is sending signals to the missing hand, and in the absence of feedback from the missing arm the signals are continuously sent without the availability of a shutoff mechanism. To counteract this, Ramachandran reasoned, the brain needs to receive visual feedback that the arm is moving in the correct manner. Ramachandran and William Hirstein “constructed a ‘virtual reality box,’” (mirror box) to allow “patients to perceive movement in a non-existent arm.”^[2] The box has a mirror and a place to put the existing and phantom arms. The patient sees his real arm in the mirror, which creates the illusion of two arms. When the patient sends motor commands to both arms, they receive visual feedback that his phantom hand is moving properly. For many patients, this technique has been effective in relieving phantom limb pain.

Randy Nudo

Randy Nudo, a professor at The University of Kansas, is another important scientist in the field of brain plasticity research. He found that if a small stroke (an infarction) is induced by impedance of blood flow to a portion of a monkey’s motor cortex, the part of the body that responds by movement will move 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. [6] With respect to the distal forelimb representation, “postinfarction mapping procedures revealed that movement representations underwent reorganization throughout the adjacent, undamaged cortex.” [6] 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 and electrical stimulation therapy.

Jon Kaas

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 long standing unilateral dorsal column lesions at cervical levels in macaque monkeys.” [8] 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 when people damage the somatosensory cortex, impairment of the body perceptions are experienced. He is trying to see how these systems (somatosensory, cognitive, motor systems) are plastic as a result of injury. [8]

Donald Stein

One of the most recent applications of neuroplasticity involves work done by a team of doctors and researchers at Emory University, specifically Dr. Donald Stein (who has been in the field for over three decades) 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. [14] Dr. Stein noticed that female mice seemed to recover from brain injuries better than male mice. Also in females, he noticed that at certain points in the estrus cycle females recovered even more. After lots of research, they attributed this difference due to the levels of progesterone. The highest level of progesterone present led to the fastest recovery of brain injury in these mice.

They developed a treatment that includes increased levels of progesterone injections to give to brain injured patients. “Administration of progesterone after traumatic brain injury^^ (TBI) and stroke reduces edema, inflammation, and neuronal cell death, and enhance spatial reference memory and sensory motor recovery.”[4] In their clinical trials, they had a group of severely injured patients that after the three days of progesterone injections there was a 60% reduction in mortality. [14] Sam* was in a horrific car accident that left him with marginal brain activity; according to the doctors, he was one point away from being brain dead. His parents decided to have him participate in Dr. Stein’s clinical trial and he was given the three-day progesterone treatment. Three years after the accident, he had achieved an inspiring recovery with no brain complications and the ability to live a healthy, normal life. [14]

Stein has done some studies in which beneficial effects have been seen to be similar in aged rats to those seen in youthful rats. As there are physiological differences in the two age groups, the model was tweaked for the elderly animals by reducing their stress levels with increased physical contact. During surgery, anesthesia was kept at a higher oxygen level with lower overall isoflurane percentage and “the aged animals were give subcutaneous lactated ringers solution post-surgery to replace fluids lost through increased bleeding.”^[3] The promising results of progesterone treatments “could have a significant impact on the clinical management of TBI.” [1] These treatments have been shown to work on human patients who receive treatment soon after the TBI. However, Dr. Stein now focuses his research on those persons who have longstanding traumatic brain injury in order to determine if progesterone treatments will assist them in the recovery of lost functions as well.

Major advancements in the field of neuroplasticity have enabled the development of novel techniques that do not require expensive or invasive medicines or surgery. “The only goal of rehabilitation in this context would be to teach the patient new strategies to overcome those lost by the injury, and plasticity would be defined by the extent to which such substitution is possible.”[13] Most of society has finally relinquished the archaic belief that the brain is fixed and immutable; this has facilitated recognition of empirical scientific evidence corroborating the existence of brain plasticity [14&15]. “An increased understanding of plasticity of the brain and spinal cord, and of behavior of innate modular mechanism in intact and [in] injured systems, will likely assist in future developments.”[7]

Richard Davidson

Richard Davidson is a Harvard-trained neuroscientist at the University of Wisconsin–Madison's W.M. Keck Laboratory for Functional Brain Imaging and Behavior. He has led experiments in cooperation with the Dalai Lama on effects of meditation on the brain. His results suggest "alterations in patterns of brain function assessed with functional magnetic resonance imaging (fMRI), changes in the cortical evoked response to visual stimuli that reflect the impact of meditation on attention, and alterations in amplitude and synchrony of high-frequency oscillations that probably play an important role in connectivity among widespread circuitry in the brain."^[4][5][6]

aortitis

Valvotomy