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76-610: The Institute did early experiments in sensory substitution , especially the substitution of tactile information for visual information to help blind people navigate and other methods to obtain accessible technology. This research is often performed by scientists who are blind, such as Josh Miele . The institute's use of botulinum toxin in humans as a therapy to treat strabismus . This initial therapeutic use led to later cosmetic use in Botox . Other impactful work involved Anthony Norcia's study of vision in infants and Erich Sutter's invention of

152-452: A functioning sensory modality. The idea of sensory substitution was introduced in the 1980s by Paul Bach-y-Rita as a means of using one sensory modality, mainly tactition , to gain environmental information to be used by another sensory modality, mainly vision . Thereafter, the entire field was discussed by Chaim-Meyer Scheff in "Experimental model for the study of changes in the organization of human sensory information processing through

228-446: A lot of factors affect the sensation triggered: stimulating voltage, current, waveform, electrode size, material, contact force, skin location, thickness and hydration. Electrotactile stimulation may involve the direct stimulation of the nerves ( percutaneous ), or through the skin ( transcutaneous ). Percutaneous application causes additional distress to the patient, and is a major disadvantage of this approach. Furthermore, stimulation of

304-532: A new device for sound-to-touch hearing at TED in 2015; his laboratory research then expanded into a company based in Palo Alto, California, called Neosensory. Neosensory devices capture sound and turn them into high-dimensional patterns of touch on the skin. Experiments by Schurmann et al. show that tactile senses can activate the human auditory cortex. Currently vibrotactile stimuli can be used to facilitate hearing in normal and hearing-impaired people. To test for

380-527: A pair of glasses worn by the user who is blind. The Haptic Belt provides vibrations that convey the direction and distance at which a person is standing in front of a user, while the VibroGlove uses spatio-temporal mapping of vibration patterns to convey facial expressions of the interaction partner. Alternatively, it has been shown that even very simple cues indicating the presence or absence of obstacles (through small vibration modules located at strategic places in

456-463: A penetrating injury to the orbit, but the nerve can also be injured by indirect trauma in which severe head impact or movement stretches or even tears the nerve. Ophthalmologists and optometrists can detect and diagnose some optic nerve diseases but neuro-ophthalmologists are often best suited to diagnose and treat diseases of the optic nerve. The International Foundation for Optic Nerve Diseases (IFOND) sponsors research and provides information on

532-422: A pentatonic scale, and low vertical locations as low-pitched musical notes. The EyeMusic conveys color information by using different musical instruments for each of the following five colors: white, blue, red, green, yellow. The EyeMusic employs an intermediate resolution of 30×50 pixels. This project, presented in 2015, proposes a new versatile mobile device and a sonification method specifically designed to

608-541: A perception of one that is lacking. With auditory sensory substitution, visual or tactile sensors detect and store information about the external environment. This information is then transformed by interfaces into sound. Most systems are auditory-vision substitutions aimed at using the sense of hearing to convey visual information to the blind. "The vOICe" converts live camera views from a video camera into soundscapes, patterns of scores of different tones at different volumes and pitches emitted simultaneously. The technology of

684-402: A perception of the sensation they lack instead of the actually stimulated sensation. For example, a leprosy patient, whose perception of peripheral touch was restored, was equipped with a glove containing artificial contact sensors coupled to skin sensory receptors on the forehead (which was stimulated). After training and acclimation, the patient was able to experience data from the glove as if it

760-465: A phenomenon called electrovibration , which allows microamperre-level currents to be felt as roughness on a surface. Vibrotactile systems use the properties of mechanoreceptors in the skin so they have fewer parameters that need to be monitored as compared to electrotactile stimulation. However, vibrotactile stimulation systems need to account for the rapid adaptation of the tactile sense. Another important aspect of tactile sensory substitution systems

836-533: A ribbon cable passing out of the mouth. A video camera records a picture, transfers it to the TDU for conversion into a tactile image. The tactile image is then projected onto the tongue via the ribbon cable where the tongue's receptors pick up the signal. After training, subjects are able to associate certain types of stimuli to certain types of visual images. In this way, tactile sensation can be used for visual perception. Sensory substitutions have also been successful with

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912-639: A sensor, a coupling system, and a stimulator. The sensor records stimuli and gives them to a coupling system which interprets these signals and transmits them to a stimulator. In case the sensor obtains signals of a kind not originally available to the bearer it is a case of sensory augmentation . Sensory substitution concerns human perception and the plasticity of the human brain; and therefore, allows us to study these aspects of neuroscience more through neuroimaging . Sensory substitution systems may help people by restoring their ability to perceive certain defective sensory modality by using sensory information from

988-409: Is a result of the absence of photoreceptors in the area of the retina where the optic nerve leaves the eye. Damage to the optic nerve typically causes permanent and potentially severe loss of vision , as well as an abnormal pupillary reflex, which is important for the diagnosis of nerve damage. The type of visual field loss will depend on which portions of the optic nerve were damaged. In general,

1064-496: Is an Open Source project hosted by SourceForge. Other approaches to the substitution of hearing for vision use binaural directional cues, much as natural human echolocation does. An example of the latter approach is the "SeeHear" chip from Caltech. Other visual-auditory substitution devices deviate from the vOICe's greyscale mapping of images. Zach Capalbo's Kromophone uses a basic color spectrum correlating to different sounds and timbres to give users perceptual information beyond

1140-471: Is available to orient themselves and maintain good posture. Touch to touch sensory substitution is where information from touch receptors of one region can be used to perceive touch in another. For example, in one experiment by Bach-y-Rita, the touch perception was restored in a patient who lost peripheral sensation from leprosy. For example, this leprosy patient was equipped with a glove containing artificial contact sensors coupled to skin sensory receptors on

1216-543: Is being conducted by, among others, the e-sense project of the Open University and Edinburgh University , the feelSpace project of the University of Osnabrück , and the hearSpace project at University of Paris . The findings of research into sensory augmentation (as well as sensory substitution in general) that investigate the emergence of perceptual experience (qualia) from the activity of neurons have implications for

1292-432: Is commonly known as a "stroke of the optic nerve" and affects the optic nerve head (where the nerve exits the eyeball). There is usually a sudden loss of blood supply and nutrients to the optic nerve head. Vision loss is typically sudden and most commonly occurs upon waking up in the morning. This condition is most common in diabetic patients 40–70 years old. Other optic nerve problems are less common. Optic nerve hypoplasia

1368-583: Is frequently associated with increased intraocular pressure that damages the optic nerve as it exits the eyeball. The trabecular meshwork assists the drainage of aqueous humor fluid. The presence of excess aqueous humor, increases IOP, yielding the diagnosis and symptoms of glaucoma. Optic neuritis is inflammation of the optic nerve. It is associated with a number of diseases, the most notable one being multiple sclerosis . The patient will likely experience varying vision loss and eye pain. The condition tends to be episodic. Anterior ischemic optic neuropathy

1444-413: Is grouped with the other eleven cranial nerves and is considered to be part of the peripheral nervous system. The optic nerve is ensheathed in all three meningeal layers ( dura , arachnoid , and pia mater ) rather than the epineurium , perineurium , and endoneurium found in peripheral nerves. Fiber tracts of the mammalian central nervous system have only limited regenerative capabilities compared to

1520-420: Is more practical to wear an orthodontic retainer holding the stimulation system than an apparatus strapped to other parts of the body, the tongue–machine interface is more popular among TVSS systems. This tongue TVSS system works by delivering electrotactile stimuli to the dorsum of the tongue via a flexible electrode array placed in the mouth. This electrode array is connected to a Tongue Display Unit [TDU] via

1596-472: Is not one modality but a result of cross-modal interactions. It is therefore concluded that while sensory substitution for vision induces visual-like perception in sighted individuals, it induces auditory or tactile perception in blind individuals. In short, blind people perceive to see through touch and audition with sensory substitution. Through experiments with a Tactile-visual sensory substitution (TVSS) device developed by Bach-y-Rita subjects described

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1672-504: Is not purely a sensory substitution system, it uses the same principles to restore perception of senses. Some tactile feedback methods of restoring a perception of touch to amputees would be direct or micro stimulation of the tactile nerve afferents. Other applications of sensory substitution systems can be seen in function robotic prostheses for patients with high level quadriplegia. These robotic arms have several mechanisms of slip detection, vibration and texture detection that they relay to

1748-501: Is produced by hundreds of activators placed on the person. The activators are solenoids of one millimeter diameter. In experiments, blind (or blindfolded ) subjects equipped with the TVSS can learn to detect shapes and to orient themselves. In the case of simple geometric shapes, it took around 50 trials to achieve 100 percent correct recognition. To identify objects in different orientations requires several hours of learning. A system using

1824-526: Is the location of the tactile stimulation. Tactile receptors are abundant on the fingertips, face, and tongue while sparse on the back, legs and arms. It is essential to take into account the spatial resolution of the receptor as it has a major effect on the resolution of the sensory substitution. A high resolution pin-arrayed display is able to present spatial information via tactile symbols, such as city maps and obstacle maps. Below you can find some descriptions of current tactile substitution systems. One of

1900-399: Is the underdevelopment of the optic nerve resulting in little to no vision in the affected eye. Tumors, especially those of the pituitary gland, can put pressure on the optic nerve causing various forms of visual loss. Similarly, cerebral aneurysms , a swelling of blood vessel(s) , can also affect the nerve. Trauma can cause serious injury to the nerve. Direct optic nerve injury can occur from

1976-402: The diencephalon ( optic stalks ) during embryonic development. As a consequence, the fibers of the optic nerve are covered with myelin produced by oligodendrocytes , rather than Schwann cells of the peripheral nervous system, and are encased within the meninges . Peripheral neuropathies like Guillain–Barré syndrome do not affect the optic nerve. However, most typically, the optic nerve

2052-430: The embodied cognition framework. Within the theoretical framework specifically the concept of sensorimotor contingencies is investigated utilizing sensory substitution. Furthermore, sensory substitution has contributed to the study of brain function, human cognition and rehabilitation. When a person becomes blind or deaf they generally do not lose the ability to hear or see; they simply lose their ability to transmit

2128-405: The multifocal electroretinogram and of the multifocal evoked potential . The Institute has originated various visual illusions, including Christopher Tyler 's development of autostereograms , and Anthony Norcia's coffer illusion. Also popular are Tyler's analysis of the position of eyes in paintings, of Mona Lisa 's smile and of Leonardo da Vinci 's possible eye condition. Over the decades,

2204-432: The optic disc to the optic chiasma and continues as the optic tract to the lateral geniculate nucleus , pretectal nuclei , and superior colliculus . The optic nerve has been classified as the second of twelve paired cranial nerves , but it is technically a myelinated tract of the central nervous system , rather than a classical nerve of the peripheral nervous system because it is derived from an out-pouching of

2280-584: The optic nerve and relayed to the brain, which re-creates the image and perceives it. Because it is the brain that is responsible for the final perception, sensory substitution is possible. During sensory substitution an intact sensory modality relays information to the visual perception areas of the brain so that the person can perceive sight. With sensory substitution, information gained from one sensory modality can reach brain structures physiologically related to other sensory modalities. Touch-to-visual sensory substitution transfers information from touch receptors to

2356-452: The suprachiasmatic nucleus and are involved in regulating the sleep-wake cycle . Its diameter increases from about 1.6 mm within the eye to 3.5 mm in the orbit to 4.5 mm within the cranial space. The optic nerve component lengths are 1 mm in the globe, 24 mm in the orbit, 9 mm in the optic canal, and 16 mm in the cranial space before joining the optic chiasm. There, partial decussation occurs, and about 53% of

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2432-460: The Institute has hosted generations of vision scientists, including 37°47′28.5″N 122°26′2.9″W  /  37.791250°N 122.434139°W  / 37.791250; -122.434139 Sensory substitution Sensory substitution is a change of the characteristics of one sensory modality into stimuli of another sensory modality. A sensory substitution system consists of three parts:

2508-455: The advance of sensory substitution devices. In sensory substitution systems, we generally have sensors that collect the data from the external environment. This data is then relayed to a coupling system that interprets and transduces the information and then replays it to a stimulator. This stimulator ultimately stimulates a functioning sensory modality. After training, people learn to use the information gained from this stimulation to experience

2584-407: The auditory areas activated by touch, Schurmann et al. tested subjects while stimulating their fingers and palms with vibration bursts and their fingertips with tactile pressure. They found that tactile stimulation of the fingers lead to activation of the auditory belt area, which suggests that there is a relationship between audition and tactition. Therefore, future research can be done to investigate

2660-517: The body can be used to perceive touch in another region. For example, in one experiment by Bach-y-Rita, touch perception was able to be restored in a patient who lost peripheral sensation due to leprosy. In order to achieve sensory substitution and stimulate the brain without intact sensory organs to relay the information, machines can be used to do the signal transduction, rather than the sensory organs. This brain–machine interface collects external signals and transforms them into electrical signals for

2736-417: The body in its natural state. Moreover, such new informations about the environment could be used not to directly replace a sensory organ but to offer a sensory information usually perceived via another, potentially harmed, sensory modality. Thus, also sensory augmentation is widely used for rehabilitation purposes as well as for investigating perceptive and cognitive neuroscience Active work in this direction

2812-472: The body) can be useful for navigation, gait stabilization and reduced anxiety when evolving in an unknown space. This approach, called the "Haptic Radar" has been studied since 2005 by researchers at the University of Tokyo in collaboration with the University of Rio de Janeiro . Similar products include the Eyeronman vest and belt, and the forehead retina system. Neuroscientist David Eagleman presented

2888-411: The brain to interpret. Generally, a camera or a microphone is used to collect visual or auditory stimuli that are used to replace lost sight and hearing, respectively. The visual or auditory data collected from the sensors is transformed into tactile stimuli that are then relayed to the brain for visual and auditory perception. Crucially, this transformation sustains the sensorimotor contingency inherent to

2964-428: The contralateral superior visual field traverse Meyer's loop to terminate in the lingual gyrus below the calcarine fissure in the occipital lobe, and fibers carrying information from the contralateral inferior visual field terminate more superiorly, to the cuneus . The optic nerve transmits all visual information including brightness perception, color perception and contrast ( visual acuity ). It also conducts

3040-440: The design and testing of non-invasive prosthetic devices for sensory impaired people". The first sensory substitution system was developed by Bach-y-Rita et al. as a means of brain plasticity in congenitally blind individuals. After this historic invention, sensory substitution has been the basis of many studies investigating perceptive and cognitive neuroscience . Sensory substitution is often employed to investigate predictions of

3116-572: The detection of approaching objects. Another successful visual-to-auditory sensory substitution device is the Prosthesis Substituting Vision for Audition (PSVA). This system utilizes a head-mounted TV camera that allows real-time, online translation of visual patterns into sound. While the patient moves around, the device captures visual frames at a high frequency and generates the corresponding complex sounds that allow recognition. Visual stimuli are transduced into auditory stimuli with

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3192-460: The earliest and most well known form of sensory substitution devices was Paul Bach-y-Rita's TVSS that converted the image from a video camera into a tactile image and coupled it to the tactile receptors on the back of his blind subject. Recently, several new systems have been developed that interface the tactile image to tactile receptors on different areas of the body such as the on the chest, brow, fingertip, abdomen, and forehead. The tactile image

3268-482: The emergence of wearable haptic actuators like vibrotactile motors, solenoids, peltier diodes, etc. At the Center for Cognitive Ubiquitous Computing at Arizona State University , researchers have developed technologies that enable people who are blind to perceive social situational information using wearable vibrotactile belts (Haptic Belt) and gloves (VibroGlove). Both technologies use miniature cameras that are mounted on

3344-424: The fibers cross to form the optic tracts. Most of these fibers terminate in the lateral geniculate body. Based on this anatomy, the optic nerve may be divided into four parts as indicated in the image at the top of this section (this view is from above as if you were looking into the orbit after the top of the skull had been removed): 1. the optic head (which is where it begins in the eyeball (globe) with fibers from

3420-584: The first 12–16 years of life) the visual cortices undergo a huge functional reorganization such that they are activated by other sensory modalities. Such cross-modal plasticity was also found through functional imaging of congenitally blind patients which showed a cross-modal recruitment of the occipital cortex during perceptual tasks such as Braille reading, tactile perception, tactual object recognition, sound localization , and sound discrimination. This may suggest that blind people can use their occipital lobe, generally used for vision, to perceive objects through

3496-401: The first mode, when the user is static, only the edges of the moving objects are sonified. With the second mode, when the user is moving, the edges of both static and moving objects are sonified. Thus, the video stream is simplified by extracting only the edges of objects that can become dangerous obstacles. The system enables the localization of moving objects, the estimation of trajectories, and

3572-541: The forehead (which was stimulated). After training and acclimation, the patient was able to experience data from the glove as if it was originating in the fingertips while ignoring the sensations in the forehead. After two days of training one of the leprosy subjects reported "the wonderful sensation of touching his wife, which he had been unable to experience for 20 years." The development of new technologies has now made it plausible to provide patients with prosthetic arms with tactile and kinesthetic sensibilities. While this

3648-482: The likelihood of a tactile–auditory sensory substitution system. One promising invention is the 'Sense organs synthesizer' which aims at delivering a normal hearing range of nine octaves via 216 electrodes to sequential touch nerve zones, next to the spine. Some people with balance disorders or adverse reactions to antibiotics develop bilateral vestibular damage (BVD). They experience difficulty maintaining posture, unstable gait, and oscillopsia . Tyler et al. studied

3724-417: The location of the damage in relation to the optic chiasm (see diagram above) will affect the areas of vision loss. Damage to the optic nerve that is anterior , or in front of the optic chiasm (toward the face) causes loss of vision in the eye on the same side as the damage. Damage at the optic chiasm itself typically causes loss of vision laterally in both visual fields or bitemporal hemianopsia (see image to

3800-399: The nerve ending in the skin to initiate the action potentials; the sensation triggered, burn, itch, pain, pressure etc. depends on the stimulating voltage. Vibrotactile stimulators use pressure and the properties of the mechanoreceptors of the skin to initiate action potentials. There are advantages and disadvantages for both these stimulation systems. With the electrotactile stimulating systems

3876-412: The patient through feedback. After more research and development, the information from these arms can be used by patients to perceive that they are holding and manipulating objects while their robotic arm actually accomplishes the task. Auditory sensory substitution systems like the tactile sensory substitution systems aim to use one sensory modality to compensate for the lack of another in order to gain

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3952-426: The pedestrian locomotion of the visually impaired. It sonifies in real-time spatial information from a video stream acquired at a standard frame rate. The device is composed of a miniature camera integrated into a glasses frame which is connected to a battery-powered minicomputer worn around the neck with a strap. The audio signal is transmitted to the user via running headphones. This system has two operating modes. With

4028-661: The perceptual experience of the TVSS as particularly visual, such that objects were perceived as if located in the external space and not on the back or skin. Further studies using the TVSS showed that such perceptual changes were only possible when the participants could actively explore their environment with the TVSS. These results have been underpinned by many other studies testing different substitution systems with blind subjects such as vision-to-tactile substitution, vision-to-auditory substitution and vision-to-vestibular substitution Such results are also reported in sighted subjects, when blindfolded and deliver further support for

4104-455: The peripheral nervous system. Therefore, in most mammals, optic nerve damage results in irreversible blindness . The fibers from the retina run along the optic nerve to nine primary visual nuclei in the brain, from which a major relay inputs into the primary visual cortex . The optic nerve is composed of retinal ganglion cell axons and glia . Each human optic nerve contains between 770,000 and 1.7 million nerve fibers, which are axons of

4180-408: The pixels of the corresponding receptive field. The frequency and the inter-aural disparity are determined by the center of gravity of the co-ordinates of the receptive field's pixels in the image (see "There is something out there: distal attribution in sensory substitution, twenty years later"; Auvray M., Hanneton S., Lenay C., O'Regan K. Journal of Integrative Neuroscience 4 (2005) 505–21). The Vibe

4256-548: The rapid adaptation of some of these receptors to sustained stimuli, those receptors require rapidly changing tactile stimulation systems in order to be optimally activated. Among all these mechanoreceptors Pacinian corpuscle offers the highest sensitivity to high frequency vibration starting from a few tens of Hz to a few kHz with the help of its specialized mechanotransduction mechanism. There have been two different types of stimulators: electrotactile or vibrotactile. Electrotactile stimulators use direct electrical stimulation of

4332-562: The respective sensory modality. This and all types of sensory substitution are only possible due to neuroplasticity . Brain plasticity refers to the brain's ability to adapt to a changing environment, for instance to the absence or deterioration of a sense. It is conceivable that cortical remapping or reorganization in response to the loss of one sense may be an evolutionary mechanism that allows people to adapt and compensate by using other senses better. Brain imaging studies have shown that upon visual impairments and blindness (especially in

4408-414: The restitution of postural control through a tactile for vestibular sensory substitution. Because BVD patients cannot integrate visual and tactile cues, they have a lot of difficulty standing. Using a head-mounted accelerometer and a brain–computer interface that employs electrotactile stimulation on the tongue, information about head-body orientation was relayed to the patient so that a new source of data

4484-438: The retina); 2. orbital part (which is the part within the orbit); 3. intracanicular part (which is the part within a bony canal known as the optic canal); and, 4. cranial part (the part within the cranial cavity, which ends at the optic chiasm). From the lateral geniculate body, fibers of the optic radiation pass to the visual cortex in the occipital lobe of the brain. In more specific terms, fibers carrying information from

4560-411: The retinal ganglion cells of one retina. In the fovea , which has high acuity, these ganglion cells connect to as few as 5 photoreceptor cells ; in other areas of the retina, they connect to thousands of photoreceptors. The optic nerve leaves the orbit (eye socket) via the optic canal , running postero-medially towards the optic chiasm , where there is a partial decussation (crossing) of fibers from

4636-627: The right). Such damage may occur with large pituitary tumors, such as pituitary adenoma . Finally, damage to the optic tract , which is posterior to, or behind the chiasm, causes loss of the entire visual field from the side opposite the damage, e.g. if the left optic tract were cut, there would be a loss of vision from the entire right visual field. Injury to the optic nerve can be the result of congenital or inheritable problems like Leber's hereditary optic neuropathy , glaucoma , trauma, toxicity , inflammation , ischemia , infection (very rarely), or compression from tumors or aneurysms . By far,

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4712-579: The sensorimotor contingency theory. Applications are not restricted to disabled persons, but also include artistic presentations, games , and augmented reality . Some examples are substitution of visual stimuli to audio or tactile, and of audio stimuli to tactile. Some of the most popular are probably Paul Bach-y-Rita's Tactile Vision Sensory Substitution (TVSS), developed with Carter Collins at Smith-Kettlewell Institute and Peter Meijer 's Seeing with Sound approach (The vOICe). Technical developments, such as miniaturization and electrical stimulation help

4788-440: The sensory signals from the periphery ( retina for visions and cochlea for hearing) to brain. Since the vision processing pathways are still intact, a person who has lost the ability to retrieve data from the retina can still see subjective images by using data gathered from other sensory modalities such as touch or audition. In a regular visual system, the data collected by the retina is converted into an electrical stimulus in

4864-614: The skin without insertion leads to the need for high voltage stimulation because of the high impedance of the dry skin, unless the tongue is used as a receptor, which requires only about 3% as much voltage. This latter technique is undergoing clinical trials for various applications, and been approved for assistance to the blind in the UK. Alternatively, the roof of the mouth has been proposed as another area where low currents can be felt. Electrostatic arrays are explored as human–computer interaction devices for touch screens . These are based on

4940-474: The temporal visual fields (the nasal hemi-retina) of both eyes. The proportion of decussating fibers varies between species, and is correlated with the degree of binocular vision enjoyed by a species. Most of the axons of the optic nerve terminate in the lateral geniculate nucleus from where information is relayed to the visual cortex , while other axons terminate in the pretectal area and are involved in reflexive eye movements . Other axons terminate in

5016-415: The term "substitution" is misleading, as it is merely an "addition" or "supplementation" not a substitution of a sensory modality. Building upon the research conducted on sensory substitution, investigations into the possibility of augmenting the body's sensory apparatus are now beginning. The intention is to extend the body's ability to sense aspects of the environment that are not normally perceivable by

5092-400: The three most common injuries to the optic nerve are from glaucoma; optic neuritis , especially in those younger than 50 years of age; and anterior ischemic optic neuropathy , usually in those older than 50. Glaucoma is a group of diseases involving loss of retinal ganglion cells causing optic neuropathy in a pattern of peripheral vision loss, initially sparing central vision. Glaucoma

5168-408: The tongue as the human–machine interface is most practical. The tongue–machine interface is both protected by the closed mouth and the saliva in the mouth provides a good electrolytic environment that ensures good electrode contact. Results from a study by Bach-y-Rita et al. show that electrotactile stimulation of the tongue required 3% of the voltage required to stimulate the finger. Also, since it

5244-457: The understanding of consciousness. Optic nerve In neuroanatomy , the optic nerve , also known as the second cranial nerve , cranial nerve II , or simply CN II , is a paired cranial nerve that transmits visual information from the retina to the brain . In humans, the optic nerve is derived from optic stalks during the seventh week of development and is composed of retinal ganglion cell axons and glial cells ; it extends from

5320-418: The use of a system that uses pixel to frequency relationship and couples a rough model of the human retina with an inverse model of the cochlea. The sound produced by this software is a mixture of sinusoidal sounds produced by virtual "sources", corresponding each to a "receptive field" in the image. Each receptive field is a set of localized pixels. The sound's amplitude is determined by the mean luminosity of

5396-566: The use of other sensory modalities. This cross modal plasticity may explain the often described tendency of blind people to show enhanced ability in the other senses. While considering the physiological aspects of sensory substitution, it is essential to distinguish between sensing and perceiving. The general question posed by this differentiation is: Are blind people seeing or perceiving to see by putting together different sensory data? While sensation comes in one modality – visual, auditory, tactile etc. – perception due to sensory substitution

5472-436: The vOICe was invented in the 1990s by Peter Meijer and uses general video to audio mapping by associating height to pitch and brightness with loudness in a left-to-right scan of any video frame. The EyeMusic user wears a miniature camera connected to a small computer (or smartphone) and stereo headphones. The images are converted into "soundscapes". The high locations on the image are projected as high-pitched musical notes on

5548-449: The vOICe's capabilities. By means of stimulating electrodes implanted into the human nervous system, it is possible to apply current pulses to be learned and reliably recognized by the recipient. It has been shown successfully in experimentation, by Kevin Warwick , that signals can be employed from force/touch indicators on a robot hand as a means of communication. It has been argued that

5624-435: The visual cortex for interpretation and perception. For example, through fMRI , one can determine which parts of the brain are activated during sensory perception. In blind persons, it is seen that while they are only receiving tactile information, their visual cortex is also activated as they perceive sight objects. Touch-to-touch sensory substitution is also possible, wherein information from touch receptors of one region of

5700-446: The visual impulses that are responsible for two important neurological reflexes: the light reflex and the accommodation reflex . The light reflex refers to the constriction of both pupils that occurs when light is shone into either eye. The accommodation reflex refers to the swelling of the lens of the eye that occurs when one looks at a near object (for example: when reading, the lens adjusts to near vision). The eye's blind spot

5776-535: Was originating in the fingertips while ignoring the sensations in the forehead. To understand tactile sensory substitution it is essential to understand some basic physiology of the tactile receptors of the skin. There are five basic types of tactile receptors: Pacinian corpuscle , Meissner's corpuscle , Ruffini endings , Merkel nerve endings , and free nerve endings . These receptors are mainly characterized by which type of stimuli best activates them, and by their rate of adaptation to sustained stimuli. Because of

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