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Somatosensory system

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The somatosensory system is a part of the sensory nervous system that is associated with the sense of touch, but includes parallel receptors and nerve pathways for the sensations of temperature, body position and movement, and pain. This complex system of sensory neurons, and neural pathways responds to changes at the surface of, or inside, the body. The axons (as afferent nerve fibers) of sensory neurons connect with, or respond to, various receptor cells. These sensory receptor cells are activated by different stimuli such as heat and nociception, giving a functional name to the responding sensory neuron, such as a thermoreceptor which carries information about temperature changes. Other receptor types include mechanoreceptors, chemoreceptors, and nociceptors which send signals along a sensory nerve to the spinal cord, where the signals may be processed by other sensory neurons, and then relayed to the brain for further processing. Sensory receptors are found all over the body including the skin, epithelial tissues, muscles, bones and joints, internal organs, and the cardiovascular system.

Touch is a crucial means of receiving information. This photo shows tactile markings identifying stairs for visually impaired people.

Somatic senses are sometimes referred to as somesthetic senses, with the understanding that somesthesis includes the sense of touch, proprioception (sense of position and movement), and (depending on usage) haptic perception.

The mapping of the body surfaces in the brain is called somatotopy. In the cortex, it is also referred to as the cortical homunculus. This brain-surface ("cortical") map is not immutable, however. Dramatic shifts can occur in response to stroke or injury.

Contents

This diagram linearly (unless otherwise mentioned) tracks the projections of all known structures that allow for touch to their relevant endpoints in the human brain.

Sensory receptors

The four mechanoreceptors in the skin each respond to different stimuli for short or long periods.

Merkel cell nerve endings are found in the basal epidermis and hair follicles; they react to low vibrations (5–15 Hz) and deep static touch such as shapes and edges. Due to having a small receptive field (extremely detailed info), they are used in areas like fingertips the most; they are not covered (shelled) and thus respond to pressures over long periods.

Tactile corpuscles react to moderate vibration (10–50 Hz) and light touch. They are located in the dermal papillae; due to their reactivity, they are primarily located in fingertips and lips. They respond in quick action potentials, unlike Merkel nerve endings. They are responsible for the ability to read Braille and feel gentle stimuli.

Pacinian corpuscles determine gross touch and distinguish rough and soft substances. They react in quick action potentials, especially to vibrations around 250 Hz (even up to centimeters away). They are the most sensitive to vibrations and have large receptor fields. Pacinian corpuscles react only to sudden stimuli so pressures like clothes that are always compressing their shape are quickly ignored. They have also been implicated in detecting the location of touch sensations on handheld tools.

Bulbous corpuscles react slowly and respond to sustained skin stretch. They are responsible for the feeling of object slippage and play a major role in the kinesthetic sense and control of finger position and movement. Merkel and bulbous cells - slow-response - are myelinated; the rest - fast-response - are not. All of these receptors are activated upon pressures that squish their shape causing an action potential.

Somatosensory cortex

Gray's Anatomy, figure 759: the sensory tract, showing the pathway (blue) up the spinal cord, through the somatosensory thalamus, to S1 (Brodmann areas 3, 1, and 2), S2, and BA7
Gray's Anatomy, figure 717: detail showing path adjacent to the insular cortex (marked insula in this figure), adjacent to S1, S2, and BA7

The postcentral gyrus includes the primary somatosensory cortex (Brodmann areas 3, 2 and 1) collectively referred to as S1.

BA3 receives the densest projections from the thalamus. BA3a is involved with the sense of relative position of neighboring body parts and amount of effort being used during movement. BA3b is responsible for distributing somatosensory information, it projects texture information to BA1 and shape and size information to BA2.

Region S2 (secondary somatosensory cortex) divides into Area S2 and parietal ventral area. Area S2 is involved with specific touch perception and is thus integrally linked with the amygdala and hippocampus to encode and reinforce memories.

Parietal ventral area is the somatosensory relay to the premotor cortex and somatosensory memory hub, BA5.

BA5 is the topographically organized somato memory field and association area.

BA1 processes texture info while BA2 processes size and shape information.

Area S2 processes light touch, pain, visceral sensation, and tactile attention.

S1 processes the remaining info (crude touch, pain, temperature).

BA7 integrates visual and proprioceptive info to locate objects in space.

The insular cortex (insula) plays a role in the sense of bodily-ownership, bodily self-awareness, and perception. Insula also plays a role in conveying info about sensual touch, pain, temperature, itch, and local oxygen status. Insula is a highly connected relay and thus is involved in numerous functions.

The somatosensory system is spread through all major parts of the vertebrate body. It consists both of sensory receptors and sensory neurons in the periphery (skin, muscle and organs for example), to deeper neurons within the central nervous system.

All afferent touch/vibration info ascends the spinal cord via the posterior (dorsal) column-medial lemniscus pathway via gracilis (T7 and below) or cuneatus (T6 and above). Cuneatus sends signals to the cochlear nucleus indirectly via spinal grey matter, this info is used in determining if a perceived sound is just villi noise/irritation. All fibers cross (left becomes right) in the medulla.

A somatosensory pathway will typically have three neurons: first-order, second-order, and third-order.

  1. The first-order neuron is a type of pseudounipolar neuron and always has its cell body in the dorsal root ganglion of the spinal nerve with a peripheral axon innervating touch mechanoreceptors and a central axon synapsing on the second-order neuron. If the somatosensory pathway is in parts of the head or neck not covered by the cervical nerves, the first-order neuron will be the trigeminal nerve ganglia or the ganglia of other sensory cranial nerves).
  2. The second-order neuron has its cell body either in the spinal cord or in the brainstem. This neuron's ascending axons will cross (decussate) to the opposite side either in the spinal cord or in the brainstem.
  3. In the case of touch and certain types of pain, the third-order neuron has its cell body in the ventral posterior nucleus of the thalamus and ends in the postcentral gyrus of the parietal lobe in the primary somatosensory cortex (or S1).
Touch can result in many different physiological reactions. Here, a baby laughs at being tickled by an older sister.

Photoreceptors, similar to those found in the retina of the eye, detect potentially damaging ultraviolet radiation (ultraviolet A specifically), inducing increased production of melanin by melanocytes. Thus tanning potentially offers the skin rapid protection from DNA damage and sunburn caused by ultraviolet radiation (DNA damage caused by ultraviolet B). However, whether this offers protection is debatable, because the amount of melanin released by this process is modest in comparison to the amounts released in response to DNA damage caused by ultraviolet B radiation.

Tactile feedback

The tactile feedback from proprioception is derived from the proprioceptors in the skin, muscles, and joints.

Balance

The receptor for the sense of balance resides in the vestibular system in the ear (for the three-dimensional orientation of the head, and by inference, the rest of the body). Balance is also mediated by the kinesthetic reflex fed by proprioception (which senses the relative location of the rest of the body to the head). In addition, proprioception estimates the location of objects which are sensed by the visual system (which provides confirmation of the place of those objects relative to the body), as input to the mechanical reflexes of the body.

Fine touch and crude touch

The cortical homunculus, a map of somatosensory areas of the brain, was devised by Wilder Penfield.

Fine touch (or discriminative touch) is a sensory modality that allows a subject to sense and localize touch. The form of touch where localization is not possible is known as crude touch. The posterior column–medial lemniscus pathway is the pathway responsible for the sending of fine touch information to the cerebral cortex of the brain.

Crude touch (or non-discriminative touch) is a sensory modality that allows the subject to sense that something has touched them, without being able to localize where they were touched (contrasting "fine touch"). Its fibres are carried in the spinothalamic tract, unlike the fine touch, which is carried in the dorsal column. As fine touch normally works in parallel to crude touch, a person will be able to localize touch until fibres carrying fine touch (Posterior column–medial lemniscus pathway) have been disrupted. Then the subject will feel the touch, but be unable to identify where they were touched.

Neural processing of social touch

The somatosensory cortex encodes incoming sensory information from receptors all over the body. Affective touch is a type of sensory information that elicits an emotional reaction and is usually social in nature, such as a physical human touch. This type of information is actually coded differently than other sensory information. Intensity of affective touch is still encoded in the primary somatosensory cortex and is processed in a similar way to emotions invoked by sight and sound, as exemplified by the increase of adrenaline caused by the social touch of a loved one, as opposed to the physical inability to touch someone you don't love.

Meanwhile, the feeling of pleasantness associated with affective touch activates the anterior cingulate cortex more than the primary somatosensory cortex. Functional magnetic resonance imaging (fMRI) data shows that increased blood-oxygen-level contrast (BOLD) signal in the anterior cingulate cortex as well as the prefrontal cortex is highly correlated with pleasantness scores of an affective touch. Inhibitory transcranial magnetic stimulation (TMS) of the primary somatosensory cortex inhibits the perception of affective touch intensity, but not affective touch pleasantness. Therefore, the S1 is not directly involved in processing socially affective touch pleasantness, but still plays a role in discriminating touch location and intensity.

Individual variation

A variety of studies have measured and investigated the causes for differences between individuals in the sense of fine touch. One well-studied area is passive tactile spatial acuity, the ability to resolve the fine spatial details of an object pressed against the stationary skin. A variety of methods have been used to measure passive tactile spatial acuity, perhaps the most rigorous being the grating orientation task. In this task subjects identify the orientation of a grooved surface presented in two different orientations, which can be applied manually or with automated equipment. Many studies have shown a decline in passive tactile spatial acuity with age; the reasons for this decline are unknown, but may include loss of tactile receptors during normal aging. Remarkably, index finger passive tactile spatial acuity is better among adults with smaller index fingertips; this effect of finger size has been shown to underlie the better passive tactile spatial acuity of women, on average, compared to men. The density of tactile corpuscles, a type of mechanoreceptor that detects low-frequency vibrations, is greater in smaller fingers; the same may hold for Merkel cells, which detect the static indentations important for fine spatial acuity. Among children of the same age, those with smaller fingers also tend to have better tactile acuity. Many studies have shown that passive tactile spatial acuity is enhanced among blind individuals compared to sighted individuals of the same age, possibly because of cross modal plasticity in the cerebral cortex of blind individuals. Perhaps also due to cortical plasticity, individuals who have been blind since birth reportedly consolidate tactile information more rapidly than sighted people.

A somatosensory deficiency may be caused by a peripheral neuropathy involving peripheral nerves of the somatosensory system. This may present as numbness or paresthesia.

Haptic technology can provide touch sensation in virtual and real environments. In the field of speech therapy, tactile feedback can be used to treat speech disorders.[citation needed]

  1. The Piezo channel receptors play key roles in the perception of pressure, touch, and proprioception (Piezo2 receptor).
  2. The TRPV1 and TRPM8 receptors play key roles in the perception of heat and cold.
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Somatosensory system
Somatosensory system Language Watch Edit 160 160 Redirected from Somatosensory Touch redirects here For other uses see Touch disambiguation This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Somatosensory system news newspapers books scholar JSTOR April 2020 Learn how and when to remove this template message This article may be too technical for most readers to understand Please help improve it to make it understandable to non experts without removing the technical details May 2021 Learn how and when to remove this template message The somatosensory system is a part of the sensory nervous system that is associated with the sense of touch but includes parallel receptors and nerve pathways for the sensations of temperature body position and movement and pain 1 This complex system of sensory neurons and neural pathways responds to changes at the surface of or inside the body The axons as afferent nerve fibers of sensory neurons connect with or respond to various receptor cells a These sensory receptor cells are activated by different stimuli such as heat and nociception giving a functional name to the responding sensory neuron such as a thermoreceptor b which carries information about temperature changes Other receptor types include mechanoreceptors chemoreceptors and nociceptors which send signals along a sensory nerve to the spinal cord where the signals may be processed by other sensory neurons and then relayed to the brain for further processing Sensory receptors are found all over the body including the skin epithelial tissues muscles bones and joints internal organs and the cardiovascular system Touch is a crucial means of receiving information This photo shows tactile markings identifying stairs for visually impaired people Somatic senses are sometimes referred to as somesthetic senses 3 with the understanding that somesthesis includes the sense of touch proprioception sense of position and movement a and depending on usage haptic perception 4 The mapping of the body surfaces in the brain is called somatotopy In the cortex it is also referred to as the cortical homunculus This brain surface cortical map is not immutable however Dramatic shifts can occur in response to stroke or injury Contents 1 System overview 1 1 Sensory receptors 1 2 Somatosensory cortex 2 Structure 3 General somatosensory pathway 3 1 Tactile feedback 3 2 Balance 3 3 Fine touch and crude touch 3 4 Neural processing of social touch 3 5 Individual variation 4 Clinical significance 5 Society and culture 6 See also 7 Notes 8 References 9 Further reading 10 External linksSystem overview Edit This diagram linearly unless otherwise mentioned tracks the projections of all known structures that allow for touch to their relevant endpoints in the human brain Sensory receptors Edit The four mechanoreceptors in the skin each respond to different stimuli for short or long periods Merkel cell nerve endings are found in the basal epidermis and hair follicles they react to low vibrations 5 15 Hz and deep static touch such as shapes and edges Due to having a small receptive field extremely detailed info they are used in areas like fingertips the most they are not covered shelled and thus respond to pressures over long periods Tactile corpuscles react to moderate vibration 10 50 Hz and light touch They are located in the dermal papillae due to their reactivity they are primarily located in fingertips and lips They respond in quick action potentials unlike Merkel nerve endings They are responsible for the ability to read Braille and feel gentle stimuli Pacinian corpuscles determine gross touch and distinguish rough and soft substances They react in quick action potentials especially to vibrations around 250 Hz even up to centimeters away They are the most sensitive to vibrations and have large receptor fields Pacinian corpuscles react only to sudden stimuli so pressures like clothes that are always compressing their shape are quickly ignored They have also been implicated in detecting the location of touch sensations on handheld tools 5 Bulbous corpuscles react slowly and respond to sustained skin stretch They are responsible for the feeling of object slippage and play a major role in the kinesthetic sense and control of finger position and movement Merkel and bulbous cells slow response are myelinated the rest fast response are not All of these receptors are activated upon pressures that squish their shape causing an action potential 6 7 8 9 Somatosensory cortex Edit Gray s Anatomy figure 759 the sensory tract showing the pathway blue up the spinal cord through the somatosensory thalamus to S1 Brodmann areas 3 1 and 2 S2 and BA7 Gray s Anatomy figure 717 detail showing path adjacent to the insular cortex marked insula in this figure adjacent to S1 S2 and BA7 The postcentral gyrus includes the primary somatosensory cortex Brodmann areas 3 2 and 1 collectively referred to as S1 BA3 receives the densest projections from the thalamus BA3a is involved with the sense of relative position of neighboring body parts and amount of effort being used during movement BA3b is responsible for distributing somatosensory information it projects texture information to BA1 and shape and size information to BA2 Region S2 secondary somatosensory cortex divides into Area S2 and parietal ventral area Area S2 is involved with specific touch perception and is thus integrally linked with the amygdala and hippocampus to encode and reinforce memories Parietal ventral area is the somatosensory relay to the premotor cortex and somatosensory memory hub BA5 BA5 is the topographically organized somato memory field and association area BA1 processes texture info while BA2 processes size and shape information Area S2 processes light touch pain visceral sensation and tactile attention S1 processes the remaining info crude touch pain temperature 10 11 12 BA7 integrates visual and proprioceptive info to locate objects in space 13 14 The insular cortex insula plays a role in the sense of bodily ownership bodily self awareness and perception Insula also plays a role in conveying info about sensual touch pain temperature itch and local oxygen status Insula is a highly connected relay and thus is involved in numerous functions Structure EditThe somatosensory system is spread through all major parts of the vertebrate body It consists both of sensory receptors and sensory neurons in the periphery skin muscle and organs for example to deeper neurons within the central nervous system General somatosensory pathway EditSee also Dorsal column medial lemniscus pathway All afferent touch vibration info ascends the spinal cord via the posterior dorsal column medial lemniscus pathway via gracilis T7 and below or cuneatus T6 and above Cuneatus sends signals to the cochlear nucleus indirectly via spinal grey matter this info is used in determining if a perceived sound is just villi noise irritation All fibers cross left becomes right in the medulla A somatosensory pathway will typically have three neurons 15 first order second order and third order The first order neuron is a type of pseudounipolar neuron and always has its cell body in the dorsal root ganglion of the spinal nerve with a peripheral axon innervating touch mechanoreceptors and a central axon synapsing on the second order neuron If the somatosensory pathway is in parts of the head or neck not covered by the cervical nerves the first order neuron will be the trigeminal nerve ganglia or the ganglia of other sensory cranial nerves The second order neuron has its cell body either in the spinal cord or in the brainstem This neuron s ascending axons will cross decussate to the opposite side either in the spinal cord or in the brainstem In the case of touch and certain types of pain the third order neuron has its cell body in the ventral posterior nucleus of the thalamus and ends in the postcentral gyrus of the parietal lobe in the primary somatosensory cortex or S1 Touch can result in many different physiological reactions Here a baby laughs at being tickled by an older sister Photoreceptors similar to those found in the retina of the eye detect potentially damaging ultraviolet radiation ultraviolet A specifically inducing increased production of melanin by melanocytes 16 Thus tanning potentially offers the skin rapid protection from DNA damage and sunburn caused by ultraviolet radiation DNA damage caused by ultraviolet B However whether this offers protection is debatable because the amount of melanin released by this process is modest in comparison to the amounts released in response to DNA damage caused by ultraviolet B radiation 16 Tactile feedback Edit The tactile feedback from proprioception is derived from the proprioceptors in the skin muscles and joints 17 Balance Edit The receptor for the sense of balance resides in the vestibular system in the ear for the three dimensional orientation of the head and by inference the rest of the body Balance is also mediated by the kinesthetic reflex fed by proprioception which senses the relative location of the rest of the body to the head 18 In addition proprioception estimates the location of objects which are sensed by the visual system which provides confirmation of the place of those objects relative to the body as input to the mechanical reflexes of the body Fine touch and crude touch Edit See also Two point discrimination The cortical homunculus a map of somatosensory areas of the brain was devised by Wilder Penfield Fine touch or discriminative touch is a sensory modality that allows a subject to sense and localize touch The form of touch where localization is not possible is known as crude touch The posterior column medial lemniscus pathway is the pathway responsible for the sending of fine touch information to the cerebral cortex of the brain Crude touch or non discriminative touch is a sensory modality that allows the subject to sense that something has touched them without being able to localize where they were touched contrasting fine touch Its fibres are carried in the spinothalamic tract unlike the fine touch which is carried in the dorsal column 19 As fine touch normally works in parallel to crude touch a person will be able to localize touch until fibres carrying fine touch Posterior column medial lemniscus pathway have been disrupted Then the subject will feel the touch but be unable to identify where they were touched Neural processing of social touch Edit The somatosensory cortex encodes incoming sensory information from receptors all over the body Affective touch is a type of sensory information that elicits an emotional reaction and is usually social in nature such as a physical human touch This type of information is actually coded differently than other sensory information Intensity of affective touch is still encoded in the primary somatosensory cortex and is processed in a similar way to emotions invoked by sight and sound as exemplified by the increase of adrenaline caused by the social touch of a loved one as opposed to the physical inability to touch someone you don t love Meanwhile the feeling of pleasantness associated with affective touch activates the anterior cingulate cortex more than the primary somatosensory cortex Functional magnetic resonance imaging fMRI data shows that increased blood oxygen level contrast BOLD signal in the anterior cingulate cortex as well as the prefrontal cortex is highly correlated with pleasantness scores of an affective touch Inhibitory transcranial magnetic stimulation TMS of the primary somatosensory cortex inhibits the perception of affective touch intensity but not affective touch pleasantness Therefore the S1 is not directly involved in processing socially affective touch pleasantness but still plays a role in discriminating touch location and intensity 19 Individual variation Edit A variety of studies have measured and investigated the causes for differences between individuals in the sense of fine touch One well studied area is passive tactile spatial acuity the ability to resolve the fine spatial details of an object pressed against the stationary skin A variety of methods have been used to measure passive tactile spatial acuity perhaps the most rigorous being the grating orientation task 20 In this task subjects identify the orientation of a grooved surface presented in two different orientations 21 which can be applied manually or with automated equipment 22 Many studies have shown a decline in passive tactile spatial acuity with age 23 24 25 the reasons for this decline are unknown but may include loss of tactile receptors during normal aging Remarkably index finger passive tactile spatial acuity is better among adults with smaller index fingertips 26 this effect of finger size has been shown to underlie the better passive tactile spatial acuity of women on average compared to men 26 The density of tactile corpuscles a type of mechanoreceptor that detects low frequency vibrations is greater in smaller fingers 27 the same may hold for Merkel cells which detect the static indentations important for fine spatial acuity 26 Among children of the same age those with smaller fingers also tend to have better tactile acuity 28 Many studies have shown that passive tactile spatial acuity is enhanced among blind individuals compared to sighted individuals of the same age 25 29 30 31 32 possibly because of cross modal plasticity in the cerebral cortex of blind individuals Perhaps also due to cortical plasticity individuals who have been blind since birth reportedly consolidate tactile information more rapidly than sighted people 33 Clinical significance EditMain article Somatosensory disorder A somatosensory deficiency may be caused by a peripheral neuropathy involving peripheral nerves of the somatosensory system This may present as numbness or paresthesia Society and culture EditMain articles Haptic technology and Haptic communication Haptic technology can provide touch sensation in virtual and real environments 34 In the field of speech therapy tactile feedback can be used to treat speech disorders citation needed See also EditAllochiria Cell signalling Golgi tendon organ Haptic communication Haptic perception Muscle spindle Molecular cellular cognition Phantom limb Physical intimacy Sensory maps Special senses Supramarginal gyrus Tactile illusion Vibratese method of communication through touch Tactile imagingNotes Edit a b The Piezo channel receptors play key roles in the perception of pressure touch and proprioception Piezo2 receptor 2 The TRPV1 and TRPM8 receptors play key roles in the perception of heat and cold 2 References Edit Sherman Carl August 12 2019 The Senses The Somatosensory system Dana Foundation New York a b The Nobel Assembly at Karolinska Institutet 4 Oct 2021 Press release The Nobel Prize in Physiology or Medicine 2021 The Nobel Prize in Physiology or Medicine 2021 David Julius and Ardem Patapoutian O Franzen R Johansson L Terenius 1996 Somesthesis and the Neurobiology of the Somatosensory Cortex Robles De La Torre G 2006 The Importance of the Sense of Touch in Virtual and Real Environments PDF IEEE Multimedia 13 3 24 30 doi 10 1109 MMUL 2006 69 S2CID 16153497 Sima Richard 23 December 2019 The Brain Senses Touch beyond the Body Scientific American Retrieved 16 February 2020 Pare Michel and Catherine Behets Paucity of Presumptive Ruffini Corpuscles in the Index Finger Pad of Humans Wiley Online Library 10 Feb 2003 Web 27 Mar 2016 Scheibert J Leurent S Prevost A Debregeas G March 2009 The role of fingerprints in the coding of tactile information probed with a biomimetic sensor Science 323 5920 1503 6 arXiv 0911 4885 Bibcode 2009Sci 323 1503S doi 10 1126 science 1166467 PMID 19179493 S2CID 14459552 Biswas A Manivannan M Srinivasan MA 2015 Vibrotactile sensitivity threshold nonlinear stochastic mechanotransduction model of the Pacinian Corpuscle IEEE Transactions on Haptics 8 1 102 13 doi 10 1109 TOH 2014 2369422 PMID 25398183 S2CID 15326972 Pare Michel and Robert Elde The Meissner Corpuscle Revised A Multiafferented Mechanoreceptor with Nociceptor Immunochemical Properties JNeurosci 15 Sept 2001 Web 27 Mar 2016 Hashim IH Kumamoto S Takemura K Maeno T Okuda S Mori Y November 2017 Tactile Evaluation Feedback System for Multi Layered Structure Inspired by Human Tactile Perception Mechanism Sensors Basel Switzerland 17 11 2601 Bibcode 2017Senso 17 2601H doi 10 3390 s17112601 PMC 5712818 PMID 29137128 Buccino G Binkofski F Fink GR Fadiga L Fogassi L Gallese V Seitz RJ Zilles K Rizzolatti G Freund HJ January 2001 Action observation activates premotor and parietal areas in a somatotopic manner an fMRI study The European Journal of Neuroscience 13 2 400 4 doi 10 1111 j 1460 9568 2001 01385 x PMID 11168545 S2CID 107700 Seelke AM Padberg JJ Disbrow E Purnell SM Recanzone G Krubitzer L August 2012 Topographic Maps within Brodmann s Area 5 of macaque monkeys Cerebral Cortex 22 8 1834 50 doi 10 1093 cercor bhr257 PMC 3388892 PMID 21955920 Geyer S Schleicher A Zilles K July 1999 Areas 3a 3b and 1 of Human Primary Somatosensory Cortex NeuroImage 10 1 63 83 doi 10 1006 nimg 1999 0440 PMID 10385582 S2CID 22498933 Disbrow E June 2002 Thalamocortical connections of the parietal ventral area PV and the second somatosensory area S2 in macaque monkeys Thalamus amp Related Systems 1 4 289 302 doi 10 1016 S1472 9288 02 00003 1 Saladin KS Anatomy and Physiology 3rd edd 2004 McGraw Hill New York a b Zukerman Wendy Skin sees the light to protect against sunshine newscientist com New Scientist Retrieved 2015 01 22 Proske U Gandevia SC October 2012 The proprioceptive senses their roles in signaling body shape body position and movement and muscle force Physiological Reviews 92 4 1651 97 doi 10 1152 physrev 00048 2011 PMID 23073629 Proske U Gandevia SC September 2009 The kinaesthetic senses The Journal of Physiology 587 Pt 17 4139 46 doi 10 1113 jphysiol 2009 175372 PMC 2754351 PMID 19581378 a b Case LK Laubacher CM Olausson H Wang B Spagnolo PA Bushnell MC May 2016 Encoding of Touch Intensity But Not Pleasantness in Human Primary Somatosensory Cortex The Journal of Neuroscience 36 21 5850 60 doi 10 1523 JNEUROSCI 1130 15 2016 PMC 4879201 PMID 27225773 Van Boven R W Johnson K O 1 December 1994 The limit of tactile spatial resolution in humans Grating orientation discrimination at the lip tongue and finger Neurology 44 12 2361 6 doi 10 1212 WNL 44 12 2361 PMID 7991127 S2CID 32255147 Craig JC 1999 Grating orientation as a measure of tactile spatial acuity Somatosensory amp Motor Research 16 3 197 206 doi 10 1080 08990229970456 PMID 10527368 Goldreich D Wong M Peters RM Kanics IM June 2009 A Tactile Automated Passive Finger Stimulator TAPS Journal of Visualized Experiments 28 doi 10 3791 1374 PMC 2726582 PMID 19578327 Stevens JC Alvarez Reeves M Dipietro L Mack GW Green BG 2003 Decline of tactile acuity in aging a study of body site blood flow and lifetime habits of smoking and physical activity Somatosensory amp Motor Research 20 3 4 271 9 doi 10 1080 08990220310001622997 PMID 14675966 S2CID 19729552 Manning H Tremblay F 2006 Age differences in tactile pattern recognition at the fingertip Somatosensory amp Motor Research 23 3 4 147 55 doi 10 1080 08990220601093460 PMID 17178550 S2CID 24407285 a b Goldreich D Kanics IM April 2003 Tactile acuity is enhanced in blindness The Journal of Neuroscience 23 8 3439 45 doi 10 1523 jneurosci 23 08 03439 2003 PMC 6742312 PMID 12716952 a b c Peters RM Hackeman E Goldreich D December 2009 Diminutive digits discern delicate details fingertip size and the sex difference in tactile spatial acuity The Journal of Neuroscience 29 50 15756 61 doi 10 1523 JNEUROSCI 3684 09 2009 PMC 3849661 PMID 20016091 Dillon YK Haynes J Henneberg M November 2001 The relationship of the number of Meissner s corpuscles to dermatoglyphic characters and finger size Journal of Anatomy 199 Pt 5 577 84 doi 10 1046 j 1469 7580 2001 19950577 x PMC 1468368 PMID 11760888 Peters RM Goldreich D 2013 Tactile spatial acuity in childhood effects of age and fingertip size PLOS ONE 8 12 e84650 Bibcode 2013PLoSO 884650P doi 10 1371 journal pone 0084650 PMC 3891499 PMID 24454612 Stevens Joseph C Foulke Emerson Patterson Matthew Q 1996 Tactile acuity aging and braille reading in long term blindness Journal of Experimental Psychology Applied 2 2 91 106 doi 10 1037 1076 898X 2 2 91 Van Boven RW Hamilton RH Kauffman T Keenan JP Pascual Leone A June 2000 Tactile spatial resolution in blind braille readers Neurology 54 12 2230 6 doi 10 1212 wnl 54 12 2230 PMID 10881245 S2CID 12053536 Goldreich D Kanics IM November 2006 Performance of blind and sighted humans on a tactile grating detection task Perception amp Psychophysics 68 8 1363 71 doi 10 3758 bf03193735 PMID 17378422 Wong M Gnanakumaran V Goldreich D May 2011 Tactile spatial acuity enhancement in blindness evidence for experience dependent mechanisms The Journal of Neuroscience 31 19 7028 37 doi 10 1523 JNEUROSCI 6461 10 2011 PMC 6703211 PMID 21562264 Bhattacharjee A Ye AJ Lisak JA Vargas MG Goldreich D October 2010 Vibrotactile masking experiments reveal accelerated somatosensory processing in congenitally blind braille readers The Journal of Neuroscience 30 43 14288 98 doi 10 1523 JNEUROSCI 1447 10 2010 PMC 3449316 PMID 20980584 Gabriel Robles De La Torre International Society for Haptics Haptic technology an animated explanation Isfh org Archived from the original on 2010 03 07 Retrieved 2010 02 26 Further reading EditBoron WF Boulpaep EL 2003 Medical Physiology Saunders pp 352 358 ISBN 0 7216 3256 4 Flanagan J R Lederman S J Neurobiology Feeling bumps and holes News and Views Nature 2001 Jul 26 412 6845 389 91 Hayward V Astley OR Cruz Hernandez M Grant D Robles De La Torre G 2004 Haptic interfaces and devices PDF Sensor Review 24 1 16 29 doi 10 1108 02602280410515770 Purves Dale 2012 Neuroscience Fifth Edition Sunderland MA Sinauer Associates Inc pp 202 203 ISBN 978 0 87893 695 3 Robles De La Torre G Hayward V July 2001 Force can overcome object geometry in the perception of shape through active touch PDF Nature 412 6845 445 8 Bibcode 2001Natur 412 445R doi 10 1038 35086588 PMID 11473320 S2CID 4413295 Robles De La Torre G 2006 The Importance of the Sense of Touch in Virtual and Real Environments PDF IEEE Multimedia 13 3 24 30 doi 10 1109 mmul 2006 69 S2CID 16153497 Grunwald M Ed Human Haptic Perception Basics and Applications Boston Basel Berlin Birkhauser 2008 ISBN 978 3 7643 7611 6 Encyclopedia of Touch Scholarpedia Expert articlesExternal links Edit Media related to Somatosensation at Wikimedia Commons Anatomy of Touch Factual documentary series by BBC Radio 4 Retrieved from https en wikipedia org w index php title Somatosensory system amp oldid 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