Human echolocation

From Wikipedia, the free encyclopedia

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 making clicking noises with their mouths. People trained to orient by echolocation can interpret the sound waves reflected by nearby objects, accurately identifying their location and size.

Background

The term "echolocation" was coined by zoologist Donald Griffin in 1944; however, reports of blind humans being able to locate silent objects date back to 1749. Human echolocation has been known and formally studied since at least the 1950s. In earlier times, human echolocation was sometimes described as "facial vision" or "obstacle sense," as it was believed that the proximity of nearby objects caused pressure changes on the skin. Only in the 1940s did a series of experiments performed in the Cornell Psychological Laboratory show that sound and hearing, rather than pressure changes on the skin, were the mechanisms driving this ability. The field of human and animal echolocation was surveyed in book form as early as 1959.

Many blind individuals passively use natural environmental echoes to sense details about their environment; however, others actively produce mouth clicks and are able to gauge information about their environment using the echoes from those clicks. Both passive and active echolocation help blind individuals learn about their environments. 

Because sighted individuals learn about their environments using vision, they often do not readily perceive echoes from nearby objects. This is due to an echo suppression phenomenon brought on by the precedence effect. However, with training, sighted individuals with normal hearing can learn to avoid obstacles using only sound, showing that echolocation is a general human ability.

Mechanics

Vision and hearing are closely related in that they can process reflected waves of energy. Vision processes light waves as they travel from their source, bounce off surfaces throughout the environment and enter the eyes. Similarly, the auditory system processes sound waves as they travel from their source, bounce off surfaces and enter the ears. Both systems can extract a great deal of information about the environment by interpreting the complex patterns of reflected energy that they receive. In the case of sound, these waves of reflected energy are called "echoes". 

Echoes and other sounds can convey spatial information that is comparable in many respects to that conveyed by light. With echoes, a blind traveler can perceive very complex, detailed, and specific information from distances far beyond the reach of the longest cane or arm. Echoes make information available about the nature and arrangement of objects and environmental features such as overhangs, walls, doorways and recesses, poles, ascending curbs and steps, planter boxes, pedestrians, fire hydrants, parked or moving vehicles, trees and other foliage, and much more. Echoes can give detailed information about location (where objects are), dimension (how big they are and their general shape), and density (how solid they are). Location is generally broken down into distance from the observer and direction (left/right, front/back, high/low). Dimension refers to the object's height (tall or short) and breadth (wide or narrow). 

By understanding the interrelationships of these qualities, much can be perceived about the nature of an object or multiple objects. For example, an object that is tall and narrow may be recognized quickly as a pole. An object that is tall and narrow near the bottom while broad near the top would be a tree. Something that is tall and very broad registers as a wall or building. Something that is broad and tall in the middle, while being shorter at either end may be identified as a parked car. An object that is low and broad may be a planter, retaining wall, or curb. And finally, something that starts out close and very low but recedes into the distance as it gets higher is a set of steps. Density refers to the solidity of the object (solid/sparse, hard/soft). Awareness of density adds richness and complexity to one's available information. For instance, an object that is low and solid may be recognized as a table, while something low and sparse sounds like a bush; but an object that is tall and broad and very sparse is probably a fence.

Neural substrates of echolocation in the blind

Echo-related activity in the brain of an early-blind echolocator is shown on the left. There is no activity evident in the brain of a sighted person (shown on the right) listening to the same echoes

 

Some blind people are skilled at echolocating silent objects simply by producing mouth clicks and listening to the returning echoes, for example Ben Underwood. Although few studies have been performed on the neural basis of human echolocation, those studies report activation of primary visual cortex during echolocation in blind expert echolocators. The driving mechanism of this brain region remapping phenomenon is known as neuroplasticity. 

In a 2014 study by Thaler and colleagues, the researchers first made recordings of the clicks and their very faint echoes using tiny microphones placed in the ears of the blind echolocators as they stood outside and tried to identify different objects such as a car, a flag pole, and a tree. The researchers then played the recorded sounds back to the echolocators while their brain activity was being measured using functional magnetic resonance imaging. Remarkably, when the echolocation recordings were played back to the blind experts, not only did they perceive the objects based on the echoes, but they also showed activity in those areas of their brain that normally process visual information in sighted people, primarily primary visual cortex or V1. This result is surprising, as visual areas, as their names suggest, are only active during visual tasks. The brain areas that process auditory information were no more activated by sound recordings of outdoor scenes containing echoes than they were by sound recordings of outdoor scenes with the echoes removed. Importantly, when the same experiment was carried out with sighted people who did not echolocate, these individuals could not perceive the objects and there was no echo-related activity anywhere in the brain. This suggests that the cortex of blind echolocators is plastic and reorganizes such that primary visual cortex, rather than any auditory area, becomes involved in the computation of echolocation tasks. 

Despite this evidence, the extent to which activation in the visual cortex in blind echolocators contributes to echolocation abilities is unclear. As previously mentioned, sighted individuals have the ability to echolocate; however, they do not show comparable activation in visual cortex. This would suggest that sighted individuals use areas beyond visual cortex for echolocation.

Notable individuals who employ echolocation

Daniel Kish

Echolocation has been further developed by Daniel Kish, who works with the blind through the non-profit organization World Access for the Blind. He leads blind teenagers hiking and mountain-biking through the wilderness, and teaches them how to navigate new locations safely, with a technique that he calls "FlashSonar". Kish had his eyes removed at the age of 13 months due to retinal cancer. He learned to make palatal clicks with his tongue when he was still a child—and now trains other blind people in the use of echolocation and in what he calls "Perceptual Mobility". Though at first resistant to using a cane for mobility, seeing it as a "handicapped" device, and considering himself "not handicapped at all", Kish developed a technique using his white cane combined with echolocation to further expand his mobility.

Kish reports that "The sense of imagery is very rich for an experienced user. One can get a sense of beauty or starkness or whatever—from sound as well as echo." He is able to distinguish a metal fence from a wooden one by the information returned by the echoes on the arrangement of the fence structures; in extremely quiet conditions, he can also hear the warmer and duller quality of the echoes from wood compared to metal.

Thomas Tajo

Thomas Tajo was born in the remote Himalayan village of Chayang Tajo in the state of Arunachal Pradesh in the north-east India and became blind around the age of 7 or 8 due to optic nerve atrophy. Tajo taught himself to echolocate. Today he lives in Belgium and works with Visioneers or World Access to impart independent navigational skills to blind individuals across the world. Tajo is also an independent researcher. He researches the cultural and biological evolutionary history of the senses and presents his findings to the scientific conferences around the world.

Ben Underwood

Ben Underwood

Nascimento: 26 de janeiro de 1992, Riverside, Califórnia, EUA

Diagnosed with retinal cancer at the age of two, American Ben Underwood had his eyes removed at the age of three.

He taught himself echolocation at the age of five. He was able to detect the location of objects by making frequent clicking noises with his tongue. This case was explained in 20/20: Medical Mysteries. He used it to accomplish such feats as running, playing basketball, riding a bicycle, rollerblading, playing football, and skateboarding. He attended school at Edward Harris Jr. Middle School. Underwood's childhood eye doctor claimed that Underwood was one of the most proficient human echolocators. 

Underwood died on January 19, 2009 at the age of 16, from the same cancer that took his vision.

Tom De Witte

Tom De Witte was born in 1979 in Belgium with bilateral congenital glaucoma. It had seemed that he would become a successful flautist until he had to give up playing music in 2005. De Witte has been completely blind since 2009 due to additional problems with his eyes. He was taught echolocation by Daniel Kish and was given the nickname "Batman from Belgium" by the press.

Dr. Lawrence Scadden

Scadden has written of his experiences with blindness. He was not born blind, but lost his sight due to illness. As a child, he learned to use echolocation well enough to ride a bicycle in traffic. (His parents thought that he still had some sight remaining.) He later participated in experiments in facial vision (White, et al. 1970). About 1998, he visited the Auditory Neuroethology Laboratory at the University of Maryland and was interviewed about his experience with facial vision. The researchers in the lab study bat echolocation and were aware of the Wiederorientierung phenomenon described by Griffin (1959), where bats, despite continuing to emit echolocation calls, use path integration in familiar acoustic space. Scadden indicated that he found echolocation required extra effort, and would not use it to navigate in familiar areas unless he was alert for obstacles, thus providing insight into the bat behavior. 

The Regional Alliance of Science, Engineering and Mathematics for Students with Disabilities (RASEM) and the Science Education for Students With Disabilities (SESD), a Special Interest Group of the National Science Teachers Association (NSTA) have created the Lawrence A. Scadden Outstanding Teacher Award of the Year for Students With Disabilities in his honor.

Lucas Murray

Lucas Murray, from Poole, Dorset, was born blind. He is believed to be one of the first British people to learn to visualise his surroundings using echolocation, and was taught by Daniel Kish.

Kevin Warwick

The scientist Kevin Warwick experimented with feeding ultrasonic pulses into the brain (via electrical stimulation from a neural implant) as an additional sensory input. In tests he was able to discern distance to objects accurately and to detect small movements of those objects.

Juan Ruiz

Blind from birth, Juan Ruiz lives in Los Angeles, California. He appeared in the first episode of Stan Lee's Superhumans, titled "Electro Man". The episode showed him capable of riding a bicycle, avoiding parked cars and other obstacles, and identifying nearby objects. He entered and exited a cave, where he determined its length and other features.

In popular media

Toph Beifong

Toph is a fictional blind girl from the animated series Avatar: Last Airbender who uses a highly advanced form of echolocation through a technique called "earthbending" (telekinetic manipulation of elemental earth). Being born blind, she has developed hyper-sensitive mechanoreceptors and is able to feel the minute vibrations in the Earth well enough to create an accurate mental picture of her surroundings. Along with her heightened sense of smell and hearing, she uses her abilities to succeed in combat, though she's left vulnerable when her opponents are airborne. Using her extremely refined abilities, she can also sense the vibrations of a person's heart-rate and breath-rate, effectively becoming a human polygraph.

Perception

The 2017 video game Perception places the player in the role of a blind woman who must use echolocation to navigate the environment.

The Last of Us

In Naughty Dog's 2013 PlayStation 3 game, The Last of Us, infected people called "clickers" use echolocation.

Imagine

In the 2012 movie Imagine, the main character teaches echolocation to students at clinic for the visually impaired. This unconventional method spurs a controversy but helps students explore the world.

Daredevil

Matthew Murdock is a defense attorney by day and a crime-fighting vigilante by night, going by the name Daredevil, from Marvel Comics. He was involved in an accident as a child where his eyes came in contact with radioactive chemicals, effectively blinding him though it did enhance his other senses (smell, hearing and touch) to superhuman levels. If he concentrates hard enough, he is able to hear a person's cry for help from blocks away. Like Toph Beifong, he can use his super-hearing to detect a person's heartbeat as well as minute changes of their breath rate and tone of voice, thus also becoming a human lie detector. Also like Toph, he uses his abilities to his advantage in combat.

Artificially stimulated echolocation for blind humans

Currently ongoing research

Project BATEYE fundamentally uses an ultrasonic sensor mounted onto a wearable pair of glasses that measures the distance to the nearest object and relays it to an Arduino board. The Arduino board then processes the measurements and then plays a tone (150–15000 Hz) for the respective distance (2 cm to 4 m) till the data from the next ultrasonic pulse (distance) comes in. This cycle is repeated almost every 5 milliseconds. The person hears sound that changes according to the distance to the nearest object. The head provides a 195-degree swivel angle and the ultrasonic sensor detects anything within a 15-degree angle. Using systematic, cognitive and computational approach of neuroscience, with the hypothesis that the usage of the occipital lobe of blind people goes into processing other sensory feedback, and using the brain as a computational unit, the machine relies on the brain processing the tone produced every 14 msec to its corresponding distance and producing a soundscape corresponding to the tones and the body navigating using the same. During experimentation, the test subject could detect obstacles as far away as 2–3 m, with horizontal or vertical movements of the head the blindfolded test subject could understand the basic shape of objects without touching them, and the basic nature of the obstacles. 

Similar research could potentially revolutionize navigation abilities of blind humans.

Tibetan independence movement

From Wikipedia, the free encyclopedia

The Tibetan independence movement is a movement for the independence of Tibet and the political separation of Tibet from China. It is principally led by the Tibetan diaspora in countries like India and the United States, and by celebrities and Tibetan Buddhists in the United States, India and Europe. The movement is not supported by the 14th Dalai Lama, who although having advocated it from 1961 to the late 1970s, proposed a sort of high-level autonomy in a speech in Strasbourg in 1988, and has since then restricted his position to either autonomy for the Tibetan people in the Tibet Autonomous Region within China, or extending the area of the autonomy to include parts of neighboring Chinese provinces inhabited by Tibetans.

 

Among other reasons for independence, campaigners assert that Tibet has been historically independent. However, some dispute this claim by using different definitions of "Tibet", "historical" and "independence". The campaigners also argue that Tibetans are currently mistreated and denied certain human rights, although the Chinese government disputes this and claims progress in human rights. Various organizations with overlapping campaigns for independence and human rights have sought to pressure various governments to support Tibetan independence or to take punitive action against China for opposing it.

Historical background

Map of East Asia in 1875, showing Qing China

 

Map of Asia in 1890, showing Tibet within Qing China. The map was published in the Meyers Konversations-Lexikon in Leipzig in 1892.

 

Map of Asia from the 1925 Finnish encyclopedia Pieni Tietosanakirja, depicting Tibet within Republican China.

 

After the Mongol Prince Köden took control of the Kokonor region in 1239, he sent his general Doorda Darqan on a reconnaissance mission into Tibet in 1240. During this expedition the Kadampa monasteries of Rwa-sgreng and Rgyal-lha-khang were burned, and 500 people killed. The death of the Mongol qaghan Ögödei in 1241 brought Mongol military activity around the world temporarily to a halt. Mongol interests in Tibet resumed in 1244, when Prince Köden sent an invitation to the leader of the Sakya sect, to come to his capital and formally surrender Tibet to the Mongols. The Sakya leader arrived in Kokonor with his two nephews Drogön Chögyal Phagpa ('Phags-pa; 1235–80) and Chana Dorje (Phyag-na Rdo-rje; 1239–67) in 1246. This event marked the incorporation of Tibet into the Mongol Empire. Tibet was under administrative rule of the Yuan dynasty until the 1350s. At that point, Tibet regained its independence.

In 1720, the Qing dynasty army entered Tibet in aid of the locals and defeated the invading forces of the Dzungar Khanate; thus began the period of Qing rule of Tibet. Later, the Chinese emperor assigned the Dalai Lama and Panchen Lama to be in charge of religious and political matters in Tibet. The Dalai Lama was leader of the area around Lhasa; the Panchen Lama was leader of the area of Shigatse Prefecture. 

By the early 18th century, the Qing dynasty had started to send resident commissioners (Ambans) to Lhasa. Tibetan factions rebelled in 1750 and killed the resident commissioners after the central government decided to reduce the number of soldiers to about 100. The Qing army entered and defeated the rebels and reinstalled the resident commissioner. The number of soldiers in Tibet was kept at about 2,000. The defensive duties were assisted by a local force which was reorganized by the resident commissioner, and the Tibetan government continued to manage day-to-day affairs as before.

At multiple places such as Lhasa, Batang, Dartsendo, Lhari, Chamdo, and Litang, Green Standard Army troops were garrisoned throughout the Dzungar war. Green Standard Army troops and Manchu Bannermen were both part of the Qing force which fought in Tibet in the war against the Dzungars. It was said that the Sichuan commander Yue Zhongqi (a descendant of Yue Fei) entered Lhasa first when the 2,000 Green Standard soldiers and 1,000 Manchu soldiers of the "Sichuan route" seized Lhasa. According to Mark C. Elliott, after 1728 the Qing used Green Standard Army troops to man the garrison in Lhasa rather than Bannermen. According to Evelyn S. Rawski, both Green Standard Army and Bannermen made up the Qing garrison in Tibet. According to Sabine Dabringhaus, Green Standard Chinese soldiers numbering more than 1,300 were stationed by the Qing in Tibet to support the 3,000-strong Tibetan army.

In the mid 19th century, arriving with an Amban, a community of Chinese troops from Sichuan who married Tibetan women settled down in the Lubu neighborhood of Lhasa, where their descendants established a community and assimilated into Tibetan culture. Hebalin was the location of where Chinese Muslim troops and their offspring lived, while Lubu was the place where Han Chinese troops and their offspring lived.

In 1904, a British mission, accompanied by a large military escort, invaded Tibet, forcing its way through to Lhasa. The 13th Dalai Lama escaped. Britain forced The Great Three Tibetan Temple signing of the Treaty of Lhasa. The head of the mission was Colonel Francis Younghusband. The principal motivation for the British mission was a fear, which proved to be unfounded, that Russia was extending its footprint into Tibet and possibly even giving military aid to the Tibetan government. But on his way to Lhasa, Younghusband killed 1,300 Tibetans in Gyangzê (as written in The Great Game by Peter Hopkirk) because the natives were in fear of what kind of unequal treaty the British would offer the Tibetans. Some documents claim that 5,000 Tibetans were killed by the British army. 

The Anglo-Chinese Convention of 1906 recognized Chinese suzerainty over the region  and the Anglo-Russian Convention of 1907, without Lhasa's or Beijing's acknowledgement, recognized the suzerainty of China over Tibet. The Qing central government claimed for sovereignty and direct rule over Tibet in 1910. The 13th Dalai Lama fled to British India in February 1910. In the same month, the Chinese government issued a proclamation 'deposing' the Dalai Lama and instigating the search for a new incarnation. When he returned from exile, the Dalai Lama declared Tibetan independence (1912). 

The subsequent outbreak of World War I and civil war in China meant that the Chinese factions only controlled part of Tibet. The government of the 13th Dalai Lama controlled Ü-Tsang (Dbus-gtsang) and western Kham, roughly coincident with the borders of the Tibet Autonomous Region today. Eastern Kham, separated from it by the Yangtze River, was under the control of Chinese warlord Liu Wenhui. The situation in Amdo (Qinghai) was more complicated, with the Xining area controlled by warlord Ma Bufang (of Hui ethnicity), who constantly strove to exert control over the rest of Amdo (Qinghai).

General Ma Fuxiang, the chairman of the Mongolian and Tibetan Affairs Commission (and also of Hui ethnicity), stated that Tibet was an integral part of the Republic of China.

"Our Party [the Kuomintang] takes the development of the weak and small and resistance to the strong and violent as our sole and most urgent task. This is even more true for those groups which are not of our kind [Ch. fei wo zulei zhe]. Now the peoples [minzu] of Mongolia and Tibet are closely related to us, and we have great affection for one another: our common existence and common honor already have a history of over a thousand years... Mongolia and Tibet's life and death are China's life and death. China absolutely cannot cause Mongolia and Tibet to break away from China's territory, and Mongolia and Tibet cannot reject China to become independent. At this time, there is not a single nation on earth except China that will sincerely develop Mongolia and Tibet."

In 1950, the People's Liberation Army of the People's Republic of China invaded Tibet, after taking over the rest of China from the Republic of China during the five years of civil war. In 1951, the Seventeen Point Agreement for the Peaceful Liberation of Tibet, a treaty signed by representatives of the Dalai Lama and the Panchen Lama, provided for rule by a joint administration under representatives of the central government and the Tibetan government. 

The Chinese have claimed that most of the population of Tibet at that time were serfs, bound to land owned by lamas. This claim has been challenged by other researchers. Any attempt at land reform or the redistribution of wealth would have proved unpopular with the established landowners. The Seventeen Point Agreement was put into effect only in Tibet proper; ergo, eastern Kham and Amdo, being outside the administration of the government of Tibet, were treated like territory belonging to any other Chinese province, with land reform implemented in full. As a result, a rebellion broke out in these regions in June 1956. The rebellion eventually spread to Lhasa, but was crushed by 1959. The 14th Dalai Lama and other government principals fled to exile in India.

Beginning in the 1950s the Central Intelligence Agency trained Tibetans as paramilitaries.

CIA and MI6 activities in Tibet (1950-1970)

According to the 14th Dalai Lama, the CIA supported the Tibetan independence movement "not because they (the CIA) cared about Tibetan independence, but as part of their worldwide efforts to destabilize all communist governments".

Agents of Western governments had infiltrated Tibet by the mid-1950s, a few years after Tibet was annexed by the People's Republic of China. British MI6 agent Sydney Wignall, in his autobiography, reveals that he and John Harrop travelled to Tibet together in 1955 posing as mountaineers. Captured by the Chinese authority, Wignell recalled that he was surprised to find two CIA agents were already under Chinese detention.

Clandestine military involvement by the U.S. began following the series of uprisings in the eastern Tibetan region of Kham in 1956. Several small groups of Khampa fighters were trained by the CIA camp and then airdropped back into Tibet with supplies. In 1958, with the rebellion in Kham ongoing, two of these fighters, Athar and Lhotse, attempted to meet with the Dalai Lama to determine whether he would cooperate with their activities. However, their request for an audience was refused by the Lord Chamberlain, Phala Thubten Wonden, who believed such a meeting would be impolitic. According to Tsering Shakya, "Phala never told the Dalai Lama or the Kashag of the arrival of Athar and Lhotse. Nor did he inform the Dalai Lama of American willingness to provide aid."

Following a mass uprising in Lhasa in 1959 during the celebration of the Tibetan New Year and the ensuing Chinese military response, the Dalai Lama went into exile in India. Some sources state that the Dalai Lama's escape was assisted by the CIA. After 1959, the CIA trained Tibetan guerrillas and provided funds and weapons for the fight against China. However, assistance was reduced during the course of the 1960s and finally ended when Richard Nixon decided to seek rapprochement with China in the early 1970s. Kenneth Conboy and James Morrison, in The CIA's Secret War in Tibet, reveal how the CIA encouraged Tibetan revolt against China — and eventually came to control its fledgling resistance movement. The New York Times reported on October 2, 1998 that the Tibetan exile movement received $1.7 million a year in the 1960s from the CIA. The Dalai Lama said in his autobiography that his brothers were responsible and that they didn't tell him about it, knowing what his reaction would be. Lodi Gyari, the Dalai Lama's personal representative in Washington, said he had no knowledge of the annual subsidy of $180,000 marked as for the Dalai Lama or how it was spent. The government in exile say they knew that the CIA trained and equipped Tibetan guerrillas who raided Tibet from a base camp in Nepal, and that the effect of those operations "only resulted in more suffering for the people of Tibet. Worse, these activities gave the Chinese government the opportunity to blame the efforts of those seeking to regain Tibetan independence on the activities of foreign powers--whereas, of course, it was an entirely Tibetan initiative." The budget figures for the CIA's Tibetan program were as follows:

• Subsidy to the Dalai Lama: US$180,000
• Support of 2,100 Tibetan guerrillas based in Nepal: US$500,000
• Other costs: US$1.06m
• Total: US$1.73m

Positions on the status of Tibet

The status of Tibet before 1950, especially in the period between 1912 and 1950, is largely in dispute between supporters and opponents of Tibetan independence. 

According to supporters of Tibetan independence, Tibet was a distinct nation and state independent between the fall of the Mongol Empire in 1368 and subjugation by the Qing Dynasty in 1720; and again between the fall of the Qing Dynasty in 1912 and its incorporation into the PRC in 1951. Moreover, even during the periods of nominal subjugation to the Yuan and Qing, Tibet was largely self-governing. As such, the Central Tibetan Administration (CTA) views current PRC rule in Tibet as illegitimate, motivated solely by the natural resources and strategic value of Tibet, and in violation of both Tibet's historical status as an independent country and the right of the Tibetan people to self-determination. It also points to PRC's autocratic and divide-and-rule policies, and assimilationist policies, regarding those as an example of imperialism bent on destroying Tibet's distinct ethnic makeup, culture, and identity, thereby cementing it as an indivisible part of China. After the fall of the Qing Dynasty, both Mongolia and Tibet declared independence and recognized each other as such. 

On the other hand, opponents assert that the PRC rules Tibet legitimately, by saying that Tibet has been part of Chinese history since the 7th century as the Tibetan Empire had close interactions with the Chinese dynasties through royal marriage. In addition to the de facto power that the Chinese has since then, Yuan Dynasty conquest in the 13th century and that all subsequent Chinese governments (Ming Dynasty, Qing Dynasty, Republic of China, and People's Republic of China) have been exercising de jure sovereignty power over Tibet.

In addition, as this position argues that no country gave Tibet diplomatic recognition between 1912 and 1950, they say that China, under the Republic of China government, continued to maintain sovereignty over the region, and the leaders of Tibet themselves acknowledged Chinese sovereignty by sending delegates to the following: the Drafting Committee for a new constitution of the Republic of China in 1925, the National Assembly of the Republic of China in 1931, the fourth National Congress of the Kuomintang in 1931, a National Assembly for drafting a new Chinese constitution in 1946, and finally to another National Assembly for drafting a new Chinese constitution in 1948. Finally, some within the PRC considers all movements aimed at ending Chinese sovereignty in Tibet, starting with British attempts in the late 19th and early 20th centuries, to the CTA today, as one long campaign abetted by malicious Western imperialism aimed at destroying Chinese integrity and sovereignty, thereby weakening China's position in the world. The PRC also points to what it calls the autocratic and theocratic policies of the government of Tibet before 1959, as well as its renunciation of South Tibet, claimed by China as a part of historical Tibet occupied by India, as well as the Dalai Lama's association with India, and as such claims the CTA has no moral legitimacy to govern Tibet.

Positions on Tibet after 1950

Tibetan exiles generally say that the number that have died in the Great Leap Forward, violence, or other unnatural causes since 1950 is approximately 1.2 million. However, this number is controversial. According to Patrick French, a supporter of the Tibetan cause who was able to view the data and calculations, the estimate is not reliable because the Tibetans were not able to process the data well enough to produce a credible total, with many persons double or triple counted. There were, however, many casualties, perhaps as many as 400,000. This figure is extrapolated from a calculation Warren W. Smith made from census reports of Tibet which show 200,000 "missing" from Tibet. Even anti-Communist resources such as the Black Book of Communism expresses doubt at the 1.2 million figure, but does note that according to the Chinese census, the total population of ethnic Tibetans in the PRC was 2.8 million in 1953, but only 2.5 million in 1964. It puts forward a figure of 800,000 deaths and alleges that as many as 10% of Tibetans were interned, with few survivors. Chinese demographers have estimated that 90,000 of the 300,000 "missing" Tibetans fled the region.

The Central Tibetan Administration also says that millions of Chinese immigrants to the TAR are diluting the Tibetans both culturally and through intermarriage. Exile groups say that despite recent attempts to restore the appearance of original Tibetan culture to attract tourism, the traditional Tibetan way of life is now irrevocably changed. It is also reported that when Hu Yaobang, the general secretary of the Communist Party of China visited Lhasa in 1980, he was unhappy when he found out the region was behind neighbouring provinces. Reforms were instituted, and since then the central government's policy in Tibet has granted most religious freedoms. But monks and nuns are still sometimes imprisoned, and many Tibetans (mostly monks and nuns) continue to flee Tibet yearly. At the same time, many Tibetans believe projects that the PRC implement to benefit Tibet, such as the China Western Development economic plan or the Qinghai-Tibet Railway, are politically motivated actions to consolidate central control over Tibet by facilitating militarization and Han Chinese migration while benefiting few Tibetans; they also believe the money funneled into cultural restoration projects as being aimed at attracting foreign tourists. They also say that there is still preferential treatment awarded to Han Chinese in the labor market as opposed to Tibetans.

The government of the PRC claims that the population of Tibet in 1737 was about 8 million. It claims that due to the 'backward' rule of the local theocracy, there was rapid decrease in the next two hundred years and the population in 1959 was only about one million. Today, the population of Greater Tibet is 7.3 million, of which 5 million is ethnic Tibetan, according to the 2000 census. According to the PRC the increase is viewed as the result of the abolishment of the theocracy and introduction of a modern, higher standard of living. Based on the census numbers, the PRC also rejects claims that the Tibetans are being swamped by Han Chinese; instead the PRC says that the border for Greater Tibet drawn by the government of Tibet in Exile is so large that it incorporates regions such as Xining that are not traditionally Tibetan in the first place, hence exaggerating the number of non-Tibetans.

The government of the PRC also rejects claims that the lives of Tibetans have deteriorated, pointing to rights enjoyed by the Tibetan language in education and in courts and says that the lives of Tibetans have been improved immensely compared to the Dalai Lama's rule before 1950. Benefits that are commonly quoted include: the GDP of Tibet Autonomous Region (TAR) today is 30 times that before 1950; it has 22,500 km of highways, all built since 1950; all secular education in the region was created after integration into the PRC; there are 25 scientific research institutes, all built by the PRC; infant mortality has dropped from 43% in 1950 to 0.661% in 2000; life expectancy has risen from 35.5 years in 1950 to 67 in 2000; the collection and publishing of the traditional Epic of King Gesar, which is the longest epic poem in the world and had only been handed down orally before; allocation of 300 million Renminbi since the 1980s to the maintenance and protection of Tibetan monasteries. The Cultural Revolution and the cultural damage it wrought upon the entire PRC is generally condemned as a nationwide catastrophe, whose main instigators (in the PRC's view, the Gang of Four) have been brought to justice and whose recurrence is unthinkable in an increasingly modernized China. The China Western Development plan is viewed by the PRC as a massive, benevolent, and patriotic undertaking by the eastern coast to help the western parts of China, including Tibet, catch up in prosperity and living standards.

Supporting organisations

"Free Tibet" LED Banner at Bird's Nest, Beijing, August 19, 2008.

 

Pro-Tibetan protesters come into contact with pro-Chinese protesters in San Francisco

 

Organisations which support the Tibetan independence movement include:

• Tibetan Youth Congress - Located at Dharamsala, the seat of the Government of Tibet in Exile in India, claims 30,000 members.
• International Tibet Independence Movement - Located in Indiana, United States. It was formed in March 1995 and is now a 501(c)(3) non-profit organization for informing about Tibetan independence.
• International Tibetan Aid Organization - Located in Amsterdam, Netherlands, this organization was formed in 2004.

However, Tenzin Gyatso, the current Dalai Lama, the spiritual leader of Tibetan Buddhists, is no longer calling for independence. He has spoken in many international venues, including the United States Congress, and the European Parliament. In 1987, he has also started campaigning for a peaceful resolution to the issue of the status of Tibet, and has since then advocated that Tibet should not become independent, but that it should be given meaningful autonomy within the People's Republic of China. This approach is known as the "Middle Way".

Some organisations either support the "Middle Way" or do not adopt a definitive stance on whether they support independence or greater autonomy. Such organisations include:

• Free Tibet Campaign - Located in London, United Kingdom, formed in 1987, stands for the right of Tibetans to determine their own future and for the future of their own country.
• International Tibet Support Network - Located in London, United Kingdom, established in 2000, umbrella organization for Tibet related organization worldwide.
• Shiv Ganga Vidya Mandir, Phaphamau, Allahabad organized a Tibet Freedom Solidarity Rally in Allahabad on 9 April 2016, drawing more than 3000 participants.

Celebrity support and Freedom Concerts

The official flag of Tibet since its introduction in the early 20th century by the 13th Dalai Lama and is now used by the Tibetan Government in Exile in India

The Tibetan independence movement receives considerable publicity from celebrities in the United States and Europe, although much of their support comes under a non-specific banner of "Free Tibet", without specifying whether they support independence for Tibet, or the kind of greater autonomy within China advocated by the Dalai Lama. 

The "Free Tibet" movement is supported by some celebrities, such as Richard Gere and Paris Hilton.

British comedian Russell Brand also occasionally mentions his support for the movement on his BBC Radio 2 show. Richard Gere is one of the most outspoken supporters of the movement and is chairman of the Board of Directors for the International Campaign for Tibet. Actress Sharon Stone caused significant controversy when she suggested that the 2008 Sichuan earthquake may have been the result of "bad karma," because the Chinese "are not being nice to the Dalai Lama, who is a good friend of mine." The Dalai Lama confirmed that he did not share Stone's views, although he confirmed that he had "met the lady".

U.S. actor and martial artist Steven Seagal has been an active supporter of Tibetan independence for several decades and makes regular donations to various Tibetan charities around the world. He has been recognized by Tibetan Lama Penor Rinpoche as the reincarnation of tulku Chungdrag Dorje, the treasure revealer of Palyul Monastery. He also claims to have the special ability of clairvoyance; in a November 2006 interview, he stated: "I was born very different, clairvoyant and a healer".

The Milarepa Fund is an organisation which organises concerts to give publicity to the Tibetan independence movement. The fund was named after Milarepa, the revered 11th-century Tibetan yogi, who used music to enlighten people. It was originally established to disburse royalties from the Beastie Boys album Ill Communication in 1994, to benefit Tibetan monks who were sampled on two songs. The Milarepa Fund organizers also jointed the Beastie Boys as they headlined the 1994 Lollapalooza Tour. Inspired by this tour, they began to organise a concert to promote Tibetan independence, in the style of Live Aid. 

Organized in June 1996, the first concert (in San Francisco) opened with Icelandic singer Björk and featured acts such as Radiohead, The Smashing Pumpkins, Cibo Matto, Rage Against the Machine, Red Hot Chili Peppers, and De La Soul. The concerts continued for three more years, which helped to generate publicity for the Tibetan independence movement. It also reportedly led to the growth of Tibetan independence organisations such as Students for a Free Tibet and Free Tibet Campaign worldwide.

Gorillaz, the virtual band have shown support through a TV spot showing animated frontman, 2D, meditating with fellow supporters outside of the Chinese embassy, followed by a brief message encouraging people to join the Free Tibet Campaign. In addition, during the holographic performances of "Clint Eastwood", 2D is wearing a shirt saying "FREE TIBET."

During the 2008 Liège–Bastogne–Liège cycling race Australian rider Cadel Evans wore an undershirt with 'Free Tibet' printed on it, bringing attention to the movement months before the 2008 Summer Olympics, held in Beijing.

Visual prosthesis

From Wikipedia, the free encyclopedia

A visual prosthesis, often referred to as a bionic eye, is an experimental visual device intended to restore functional vision in those suffering from partial or total blindness. Many devices have been developed, usually modeled on the cochlear implant or bionic ear devices, a type of neural prosthesis in use since the mid-1980s. The idea of using electrical current (e.g., electrically stimulating the retina or the visual cortex) to provide sight dates back to the 18th century, discussed by Benjamin Franklin, Tiberius Cavallo, and Charles LeRoy.

Biological considerations

The ability to give sight to a blind person via a bionic eye depends on the circumstances surrounding the loss of sight. For retinal prostheses, which are the most prevalent visual prosthetic under development (due to ease of access to the retina among other considerations), patients with vision loss due to degeneration of photoreceptors (retinitis pigmentosa, choroideremia, geographic atrophy macular degeneration) are the best candidate for treatment. Candidates for visual prosthetic implants find the procedure most successful if the optic nerve was developed prior to the onset of blindness. Persons born with blindness may lack a fully developed optical nerve, which typically develops prior to birth, though neuroplasticity makes it possible for the nerve, and sight, to develop after implantation.

Technological considerations

Visual prosthetics are being developed as a potentially valuable aid for individuals with visual degradation. Argus II, co-developed at the University of Southern California (USC) Eye Institute and manufactured by Second Sight Medical Products Inc., is now the only such device to have received marketing approval (CE Mark in Europe in 2011). Most other efforts remain investigational; the Retina Implant AG's Alpha IMS won a CE Mark July 2013 and is a significant improvement in resolution. It is not, however, FDA-approved in the US.

Ongoing projects

Argus retinal prosthesis

Mark Humayun, who joined the faculty of the Keck School of Medicine of USC Department of Ophthalmology in 2001; Eugene Dejuan, now at the University of California San Francisco; engineer Howard D. Phillips; bio-electronics engineer Wentai Liu, now at University of California Los Angeles; and Robert Greenberg, now of Second Sight, were the original inventors of the active epi-retinal prosthesis and demonstrated proof of principle in acute patient investigations at Johns Hopkins University in the early 1990s. In the late 1990s the company Second Sight was formed by Greenberg along with medical device entrepreneur, Alfred E. Mann, Their first-generation implant had 16 electrodes and was implanted in six subjects by Humayun at University of Southern California between 2002 and 2004. In 2007, the company began a trial of its second-generation, 60-electrode implant, dubbed the Argus II, in the US and in Europe. In total 30 subjects participated in the studies spanning 10 sites in four countries. In the spring of 2011, based on the results of the clinical study which were published in 2012, Argus II was approved for commercial use in Europe, and Second Sight launched the product later that same year. The Argus II was approved by the United States FDA on 14 February 2013. Three US government funding agencies (National Eye Institute, Department of Energy, and National Science Foundation) have supported the work at Second Sight, USC, UCSC, Caltech, and other research labs.

Microsystem-based visual prosthesis (MIVP)

Designed by Claude Veraart at the University of Louvain, this is a spiral cuff electrode around the optic nerve at the back of the eye. It is connected to a stimulator implanted in a small depression in the skull. The stimulator receives signals from an externally worn camera, which are translated into electrical signals that stimulate the optic nerve directly.

Implantable miniature telescope

Although not truly an active prosthesis, an Implantable Miniature Telescope is one type of visual implant that has met with some success in the treatment of end-stage age-related macular degeneration. This type of device is implanted in the eye's posterior chamber and works by increasing (by about three times) the size of the image projected onto the retina in order to overcome a centrally located scotoma or blind spot.

Created by VisionCare Ophthalmic Technologies in conjunction with the CentraSight Treatment Program, the telescope is about the size of a pea and is implanted behind the iris of one eye. Images are projected onto healthy areas of the central retina, outside the degenerated macula, and is enlarged to reduce the effect the blind spot has on central vision. 2.2x or 2.7x magnification strengths make it possible to see or discern the central vision object of interest while the other eye is used for peripheral vision because the eye that has the implant will have limited peripheral vision as a side effect. Unlike a telescope which would be hand-held, the implant moves with the eye which is the main advantage. Patients using the device may however still need glasses for optimal vision and for close work. Before surgery, patients should first try out a hand-held telescope to see if they would benefit from image enlargement. One of the main drawbacks is that it cannot be used for patients who have had cataract surgery as the intraocular lens would obstruct insertion of the telescope. It also requires a large incision in the cornea to insert.

A Cochrane systematic review seeking to evaluate the effectiveness and safety of the implantable miniature telescope for patients with late or advanced age-related macular degeneration found only one ongoing study evaluating the OriLens intraocular telescope, with results expected in 2020.

Tübingen MPDA Project Alpha IMS

A Southern German team led by the University Eye Hospital in Tübingen, was formed in 1995 by Eberhart Zrenner to develop a subretinal prosthesis. The chip is located behind the retina and utilizes microphotodiode arrays (MPDA) which collect incident light and transform it into electrical current stimulating the retinal ganglion cells. As natural photoreceptors are far more efficient than photodiodes, visible light is not powerful enough to stimulate the MPDA. Therefore, an external power supply is used to enhance the stimulation current. The German team commenced in vivo experiments in 2000, when evoked cortical potentials were measured from Yucatán micropigs and rabbits. At 14 months post implantation, the implant and retina surrounding it were examined and there were no noticeable changes to anatomical integrity. The implants were successful in producing evoked cortical potentials in half of the animals tested. The thresholds identified in this study were similar to those required in epiretinal stimulation. Later reports from this group concern the results of a clinical pilot study on 11 participants suffering from RP. Some blind patients were able to read letters, recognize unknown objects, localize a plate, a cup and cutlery. Two of the patients were found to make microsaccades similar to those of healthy control participants, and the properties of the eye movements depended on the stimuli that the patients were viewing—suggesting that eye movements might be useful measures for evaluating vision restored by implants. In 2010 a new multicenter Study has been started using a fully implantable device with 1500 Electrodes Alpha IMS (produced by Retina Implant AG, Reutlingen, Germany), 10 patients included so far; first results have been presented at ARVO 2011. The first UK implantations took place in March 2012 and were led by Robert MacLaren at the University of Oxford and Tim Jackson at King's College Hospital in London. David Wong also implanted the Tübingen device in a patient in Hong Kong. In all cases previously blind patients had some degree of sight restored.

Harvard/MIT Retinal Implant

Joseph Rizzo and John Wyatt at the Massachusetts Eye and Ear Infirmary and MIT began researching the feasibility of a retinal prosthesis in 1989, and performed a number of proof-of-concept epiretinal stimulation trials on blind volunteers between 1998 and 2000. They have since developed a subretinal stimulator, an array of electrodes, that is placed beneath the retina in the subretinal space and receives image signals beamed from a camera mounted on a pair of glasses. The stimulator chip decodes the picture information beamed from the camera and stimulates retinal ganglion cells accordingly. Their second generation prosthesis collects data and sends it to the implant through RF fields from transmitter coils that are mounted on the glasses. A secondary receiver coil is sutured around the iris.

Artificial silicon retina (ASR)

The brothers Alan Chow and Vincent Chow have developed a microchip containing 3500 photodiodes, which detect light and convert it into electrical impulses, which stimulate healthy retinal ganglion cells. The ASR requires no externally worn devices.

The original Optobionics Corp. stopped operations, but Chow acquired the Optobionics name, the ASR implants and plans to reorganize a new company under the same name. The ASR microchip is a 2mm in diameter silicon chip (same concept as computer chips) containing ~5,000 microscopic solar cells called "microphotodiodes" that each have their own stimulating electrode.

Photovoltaic retinal prosthesis (PRIMA)

Daniel Palanker and his group at Stanford University have developed a photovoltaic retinal prosthesis that includes a subretinal photodiode array and an infrared image projection system mounted on video goggles. Images captured by video camera are processed in a pocket PC and displayed on video goggles using pulsed near-infrared (IR, 880–915 nm) light. These images are projected onto the retina via natural eye optics, and photodiodes in the subretinal implant convert light into pulsed bi-phasic electric current in each pixel. Electric current flowing through the tissue between the active and return electrode in each pixel stimulates the nearby inner retinal neurons, primarily the bipolar cells, which transmit excitatory responses to the retinal ganglion cells. This technology is being commercialized by Pixium Vision (PRIMA), and is being evaluated in a clinical trial (2018). Following this proof of concept, Palanker group is focusing now on developing pixels smaller than 50μm using 3-D electrodes and utilizing the effect of retinal migration into voids in the subretinal implant.

Bionic Vision Australia

An Australian team led by Professor Anthony Burkitt is developing two retinal prostheses. The Wide-View device combines novel technologies with materials that have been successfully used in other clinical implants. This approach incorporates a microchip with 98 stimulating electrodes and aims to provide increased mobility for patients to help them move safely in their environment. This implant will be placed in the suprachoroidal space. Researchers expect the first patient tests to begin with this device in 2013. 

The Bionic Vision Australia consortium is concurrently developing the High-Acuity device, which incorporates a number of new technologies to bring together a microchip and an implant with 1024 electrodes. The device aims to provide functional central vision to assist with tasks such as face recognition and reading large print. This high-acuity implant will be inserted epiretinally. Patient tests are planned for this device in 2014 once preclinical testing has been completed. 

Patients with retinitis pigmentosa will be the first to participate in the studies, followed by age-related macular degeneration. Each prototype consists of a camera, attached to a pair of glasses which sends the signal to the implanted microchip, where it is converted into electrical impulses to stimulate the remaining healthy neurons in the retina. This information is then passed on to the optic nerve and the vision processing centres of the brain. 

The Australian Research Council awarded Bionic Vision Australia a $42 million grant in December 2009 and the consortium was officially launched in March 2010. Bionic Vision Australia brings together a multidisciplinary team, many of whom have extensive experience developing medical devices such as the cochlear implant (or 'bionic ear').

Dobelle Eye

Similar in function to the Harvard/MIT device, except the stimulator chip sits in the primary visual cortex, rather than on the retina. Many subjects have been implanted with a high success rate and limited negative effects. Still in the developmental phase, upon the death of Dobelle, selling the eye for profit was ruled against in favor of donating it to a publicly funded research team.

Intracortical visual prosthesis

The Laboratory of Neural Prosthetics at Illinois Institute Of Technology (IIT), Chicago, is developing a visual prosthetic using intracortical electrode arrays. While similar in principle to the Dobelle system, the use of intracortical electrodes allow for greatly increased spatial resolution in the stimulation signals (more electrodes per unit area). In addition, a wireless telemetry system is being developed to eliminate the need for transcranial wires. Arrays of activated iridium oxide film (AIROF)-coated electrodes will be implanted in the visual cortex, located on the occipital lobe of the brain. External hardware will capture images, process them, and generate instructions which will then be transmitted to implanted circuitry via a telemetry link. The circuitry will decode the instructions and stimulate the electrodes, in turn stimulating the visual cortex. The group is developing a wearable external image capture and processing system to accompany the implanted circuitry. Studies on animals and psyphophysical studies on humans are being conducted to test the feasibility of a human volunteer implant.