Touch is defined as direct contact between two physical bodies. In neuroscience, touch describes the special sense by which contact with the body is perceived in the conscious mind. Touch allows us to recognise objects held in the hand and use them as tools. Because the skin is elastic, it forms a mirror image of object contours, allowing us to perceive their size, shape and texture. Four classes of mechanoreceptors use Piezo2 protein complexes to distinguish the form, weight, motion, vibration and hand posture that define each object. Parallel messages from approximately 20 000 nerve fibres are integrated by neurons in the cerebral cortex that detect specific object classes. Some touch involves active movement – stroking, tapping or pressing – whereby a limb is moved against another surface. The sensory and motor components of touch are connected anatomically in the brain and are important functionally in guiding skilled behaviours.

Key Concepts

  • The sense of touch is mediated by four mechanoreceptors located in the skin: the Meissner corpuscles, Merkel cells, Pacinian corpuscles and Ruffini endings. All of these receptors express the protein complex Piezo2 formed by three identical large protein subunits.
  • The most numerous touch receptors—Meissner corpuscles—detect textures and edges as the hand is moved over surfaces because of their location along the margins of the fingerprint ridges and signal the speed and direction of movement with rapidly adapting firing patterns.
  • The Merkel cells—small receptor cells clustered at the centre of the fingerprint ridge and in small domes elsewhere on the body—signal the weight, form and surface features of objects contacting the skin with a continuous, slowly adapting spike train proportional to pressure.
  • The most sensitive touch receptors—Pacinian corpuscles—provide sensory information from tools grasped or moved by the hand because of their high sensitivity to vibration transmitted through the object. They sense vibration through pens or pencils when writing or drawing.
  • Each mechanoreceptor signals information about touch applied to a small patch of skin—called its receptive field—that corresponds to the anatomical location of the receptor in the body.
  • Several thousand mechanoreceptors are stimulated in each finger when an object is grasped in the hand.
  • The information provided by individual touch receptors is transmitted in parallel via the dorsal columns, medial lemniscus and ventral posterior thalamus to the parietal lobe of the cerebral cortex where it is integrated to reconstruct a tactile image of the entire object.
  • The primary somatic sensory (S‐I) cortex—located in the postcentral gyrus—contains a topographic map of the body in which regions that are touched most frequently and densely innervated are magnified so that the majority of somatosensory cortical neurons encode touch information provided from the hands, feet or lips.
  • Responses of neurons in the second somatic sensory (S‐II) cortex—located on the upper bank of the lateral fissure—are modulated not only by touch information from mechanoreceptors in the skin but also by the context, subjective attention, behavioural significance and previous experience of similar stimuli.
  • The posterior parietal cortex integrates tactile, proprioceptive and visual information about object properties with corollary signals from motor centres in the cerebral cortex to guide hand actions when grasping and manipulating objects in skilled tasks.

Keywords: somatosensory system; tactile sense; skin senses; mechanosensation; stereognosis; hand

Figure 1. Cross section of the skin showing the major classes of cutaneous mechanoreceptors. Modified from Gardner EP, Martin JH and Jessell TM () The bodily senses. In: Kandel ER, Schwartz JH and Jessell TM (eds) Principles of Neural Science, 4th edn. pp. 430–450. New York: McGraw‐Hill.
Figure 2. Images of the principal touch receptors in the skin. (a) Meissner corpuscles and Merkel cells are revealed in immunostained confocal images of a papillary (fingerprint) ridge from the human fingertip. Meissner corpuscles (white arrows) are located below the epidermis (blue) along the lateral borders of each ridge; each corpuscle is innervated by at least two RA1 fibres. SA1 fibres innervate clusters of neighbouring Merkel cells (yellow arrow) in the centre of the ridge, providing localised signals of pressure applied to the finger. The fibres lose their myelin sheaths (red) when entering the receptor capsule exposing broad terminal bulbs (green) where sensory transduction occurs. Photograph courtesy of M Nolano; reproduced with permission from Nolano et al. (). (b) Photograph of a Pacinian corpuscle (∼1.6 mm in length) located in the mesentery of the abdominal wall. Each Pacinian corpuscle is innervated by a single RA2 fibre. Reproduced courtesy of S Bolanowski from Bell et al. ().
Figure 3. Receptive fields in the human hand mapped with single fibre recordings from the median nerve. Each coloured area on the hands indicates the receptive field of an individual sensory nerve fibre. Receptive fields of Merkel disk receptors and Meissner corpuscles cover spotlike patches of skin on the hand, and are smaller than those of Ruffini endings and Pacinian corpuscles because of differences in receptor cell size. SA1 and RA1 fibres innervate clusters of mechanoreceptors; SA2 and RA2 fibres innervate only one large receptor cell. The neural responses in the lower panels illustrate responses of the four fibre types to steady pressure on the skin. Modified from Johansson RS and Vallbo AB () Tactile sensory coding in the glabrous skin of the human hand. Trends in Neuroscience 6: 27–32.
Figure 4. The homotrimeric structure of Piezo2 ion channels as modelled from cryoelectron microscopy. Mammalian Piezo2 proteins contain approximately 2800 amino acid residues arranged in 38 transmembrane segments; three Piezo2 protein chains combine to form mechanosensory ion channels in touch receptor membranes. (a) Visualisation of the three‐dimensional structure of Piezo2 ion channels as viewed from three different angles; the homotrimeric structure resembles those previously constructed for Piezo1 channels (Guo and MacKinnon, ). (b) A side view of the surface electrostatic potential, showing the hydrophobic transmembrane region (marked by green dashed lines). The midplane opening diameter, depth, surface area (Adome) and projection area (Aproj) of the illustrated dome are labelled. The colour bar indicates the surface electrostatic potential, ranging from negative (red) to positive (blue). (c) Labelled models of the principal structural features of the ion channel in cell membranes. From Wang L, Zhou H, Zhang M, Liu W, Deng T, Zhao Q, Li Y, Lei J and Li X (2019) Structure and mechanogating of the mammalian tactile channel PIEZO2. Nature 573: 225–229.
Figure 5. Somatosensory areas of the cerebral cortex. (a) Lateral view of the brain showing primary (S‐I), secondary (S‐II) and posterior parietal areas. (b) Coronal section through the postcentral gyrus indicating the cytoarchitectural subdivisions of S‐I cortex, and their relation to S‐II cortex. (c) Schematic outline of the hierarchical connections to and from the S‐I cortex. Neurons projecting from the thalamus send their axons to areas 3a and 3b, but some also project to areas 1 and 2. Neurons in areas 3a and 3b project to areas 1 and 2. Information from the four areas of S‐I cortex is conveyed to neurons in the posterior parietal cortex (area 5) and S‐II cortex. From Gardner EP and Johnson KO (2012) The somatosensory system: receptors and central pathways. In: Kandel ER, Schwartz JH, Jessell TM, Siegelbaum SA and Hudspeth AJ (eds) Principles of Neural Science, 5th edn. pp. 475‐497. New York: McGraw‐Hill.
Figure 6. Spike trains recorded from neurons in Brodmann area 2 of the cerebral cortex in response to motion across their receptive fields; the direction of motion is indicated by upward and downward deflections in the lower trace and by arrows on the hands. (a) A motion‐sensitive neuron responds to stroking the skin in all directions. (b) A direction‐sensitive neuron responds strongly to motion towards the ulnar side of the palm but fails to respond to motion along the same path in the opposite direction. Responses to distal or proximal movements are weaker. (c) An orientation‐sensitive neuron responds better to motion across a finger (ulnar–radial) than to motion along the finger (distal–proximal) but does not distinguish ulnar from radial nor proximal from distal directions. From Gardner EP and Johnson KO (2012) The somatosensory system: receptors and central pathways. In: Kandel ER, Schwartz JH, Jessell TM, Siegelbaum SA and Hudspeth AJ (eds) Principles of Neural Science, 5th edn. pp. 475–497. New York: McGraw‐Hill. Reproduced with permission of McGraw‐Hill.


Abraira VE and Ginty DD (2013) The sensory neurons of touch. Neuron 79: 618–639.

Bell J, Bolanowski S and Holmes MH (1994) The structure and function of Pacinian corpuscles: a review. Progress in Neurobiology 42: 79–128.

Bolanowski SJ and Pawson L (2003) Organization of Meissner corpuscles in the glabrous skin of monkey and cat. Somatosensory and Motor Research 20: 223–231.

Brochier T, Boudreau M‐J, Paré M and Smith AM (1999) The effects of muscimol inactivation of small regions of motor and somatosensory cortex on independent finger movements and force control in the precision grip. Experimental Brain Research 128: 31–40.

Brochier T and Umiltà MA (2007) Cortical control of grasp in non‐human primates. Current Opinion in Neurobiology 17: 637–643.

Buneo CA and Andersen RA (2006) The posterior parietal cortex: sensorimotor interface for the planning and online control of visually guided movements. Neuropsychologia 44: 2594–2606.

Carlson M (1981) Characteristics of sensory deficits following lesions of Brodmann's areas 1 and 2 in the postcentral gyrus of Macaca mulatta. Brain Research 204: 424–430.

Connor CE, Hsiao SS, Phillips JR and Johnson KO (1990) Tactile roughness: neural codes that account for psychophysical magnitude estimates. Journal of Neuroscience 10: 3823–3836.

Costanzo RM and Gardner EP (1980) A quantitative analysis of responses of direction‐sensitive neurons in somatosensory cortex of alert monkeys. Journal of Neurophysiology 43: 1319–1341.

Coste B, Xiao B, Santos JS, et al. (2012) Piezo proteins are pore‐forming subunits of mechanically activated channels. Nature 483: 176–181.

Culham JC and Valyear KF (2006) Human parietal cortex in action. Current Opinion in Neurobiology 16: 205–212.

DiCarlo JJ, Johnson KO and Hsiao SS (1998) Structure of receptive fields in area 3b of primary somatosensory cortex in the alert monkey. Journal of Neuroscience 18: 2626–2264.

Flanagan JR, Vetter P, Johansson RS and Wolpert DM (2003) Prediction precedes control in motor learning. Current Biology 13: 146–150.

Fogassi L and Luppino G (2005) Motor functions of the parietal lobe. Current Opinion in Neurobiology 15: 626–631.

Freund HJ (2003) Somatosensory and motor disturbances in patients with parietal lobe lesions. Advances in Neurology 93: 179–193.

Friedman DP, Murray EA, O'Neill JB and Mishkin M (1986) Cortical connections of the lateral sulcus of macaques: evidence for a corticolimbic pathway for touch. Journal of Comparative Neurology 252: 323–347.

Friedman RM, Chen LM and Roe AW (2004) Modality maps within primate somatosensory cortex. Proceedings of the National Academy of Sciences of the USA 101: 12724–12729.

Gardner EP and Costanzo RM (1980) Neuronal mechanisms underlying direction sensitivity of somatosensory cortical neurons in alert monkeys. Journal of Neurophysiology 43: 1342–1354.

Gardner EP (1988) Somatosensory cortical mechanisms of feature detection in tactile and kinesthetic discrimination. Canadian Journal of Physiology and Pharmacology 66: 439–454.

Gardner EP, Martin JH and Jessell TM (2000) The bodily senses. In: Kandel ER, Schwartz JH and Jessell TM (eds) Principles of Neural Science, 4th edn, pp 430–450. McGraw‐ Hill: New York.

Gardner EP, Babu KS, Reitzen SD, et al. (2007) Neurophysiology of prehension: I. Posterior parietal cortex and object‐oriented hand behaviors. Journal of Neurophysiology 97: 387–406.

Gardner EP and Johnson KO (2012a) The somatosensory system: receptors and central pathways. In: Kandel ER, Schwartz JH, Jessell TM, Siegelbaum SA and Hudspeth AJ (eds) Principles of Neural Science, 5th edn, pp 475–497. McGraw‐Hill: New York.

Gardner EP and Johnson KO (2012b) Touch. In: Kandel ER, Schwartz JH, Jessell TM, Siegelbaum SA and Hudspeth AJ (eds) Principles of Neural Science, 5th edn, pp 498–529. McGraw‐Hill: New York.

Goodwin AW and Wheat HE (2004) Sensory signals in neural populations underlying tactile perception and manipulation. Annual Review of Neuroscience 27: 53–77.

Guo YR and MacKinnon R (2017) Structure‐based membrane dome mechanism for Piezo mechanosensitivity. eLife 6: e33660.

Hikosaka O, Tanaka M, Sakamoto M and Iwamura Y (1985) Deficits in manipulative behaviors induced by local injections of muscimol in the first somatosensory cortex of the conscious monkey. Brain Research 325: 375–380.

Hsiao SS, Lane J and Fitzgerald P (2002) Representation of orientation in the somatosensory system. Behavioural Brain Research 135: 93–103.

Hyvärinen J and Poranen A (1978) Movement‐sensitive and direction and orientation‐selective cutaneous receptive fields in the hand area of the post‐central gyrus in monkeys. Journal of Physiology (London) 283: 523–537.

Iggo A and Andres KH (1982) Morphology of cutaneous receptors. Annual Review of Neuroscience 5: 1–31.

Iwamura Y, Tanaka M, Sakamoto M and Hikosaka O (1993) Rostrocaudal gradients in neuronal receptive field complexity in the finger region of the alert monkey's postcentral gyrus. Experimental Brain Research 92: 360–368.

Jeannerod M, Arbib MA, Rizzolatti G and Sakata H (1995) Grasping objects: the cortical mechanisms of visuomotor transformation. Trends in Neuroscience 18: 314–320.

Jenmalm P and Johansson RS (1997) Visual and somatosensory information about object shape control manipulative finger tip forces. Journal of Neuroscience 17: 4486–4499.

Johansson RS and Vallbo AB (1983) Tactile sensory coding in the glabrous skin of the human hand. Trends in Neuroscience 6: 27–32.

Johansson RS (1996) Sensory control of dexterous manipulation in humans. In: Wing AM, Haggard P and Flanagan JR (eds) Hand and Brain, pp 381–414. Academic Press: San Diego, CA.

Johansson RS and Flanagan JR (2009) Coding and use of tactile signals from the fingertips in object manipulation tasks. Nature Reviews. Neuroscience 10: 345–359.

Johnson KO and Hsiao SS (1992) Neural mechanisms of tactual form and texture perception. Annual Review of Neuroscience 15: 227–250.

Johnson KO (2001) The roles and functions of cutaneous mechanoreceptors. Current Opinion in Neurobiology 11: 455–461.

Jones EG and Powell TPS (1969) Connexions of the somatic sensory cortex of the rhesus monkey. I. Ipsilateral cortical connexions. Brain 92: 477–502.

Jones EG and Friedman DP (1982) Projection pattern of functional components of thalamic ventrobasal complex on monkey somatosensory cortex. Journal of Neurophysiology 489: 521–544.

Khalsa PS, Friedman RM, Srinivasan MA and LaMotte RH (1998) Encoding of shape and orientation of objects indented into the monkey fingerpad by populations of slowly and rapidly adapting mechanoreceptors. Journal of Neurophysiology 79: 3238–3251.

Klatzky RA, Lederman SJ and Metzger VA (1985) Identifying objects by touch: an “expert system”. Perception and Psychophysics 37: 299–302.

LaMotte RH and Mountcastle VB (1979) Disorders in somesthesis following lesions of parietal lobe. Journal of Neurophysiology 42: 400–419.

Lechner SG and Lewin GR (2013) Hairy sensation. Physiology 28: 142–150.

Lieber JD, Xia X, Weber AI and Bensmaia SJ (2017) The neural code for tactile roughness in the somatosensory nerves. Journal of Neurophysiology 118: 3107–3117.

Maksimovic S, Nakatani M, Baba Y, et al. (2014) Epidermal Merkel cells are mechanosensory cells that tune mammalian touch receptors. Nature 509: 617–621.

Milner AD and Goodale MA (1995) The Visual Brain in Action. Oxford University Press: Oxford.

Monzée J, Lamarre Y and Smith AM (2003) The effects of digital anesthesia on force control using a precision grip. Journal of Neurophysiology 89: 672–683.

Mountcastle VB, Lynch JC, Georgopoulos A, Sakata H and Acuna C (1975) Posterior parietal association cortex of the monkey: command functions for operations within extra‐personal space. Journal of Neurophysiology 38: 871–908.

Mountcastle VB (1997) The columnar organization of the neocortex. Brain 120: 701–722.

Muniak MA, Ray S, Hsiao SS, Dammann JF and Bensmaia SJ (2007) The neural coding of stimulus intensity: linking the population response of mechanoreceptive afferents with psychophysical behavior. Journal of Neuroscience 27: 11687–11699.

Murata A, Gallese V, Luppino G, Kaseda M and Sakata H (2000) Selectivity for the shape, size and orientation of objects for grasping in neurons of monkey parietal area AIP. Journal of Neurophysiology 83: 2580–2601.

Nelson RJ, Sur M, Felleman DJ and Kaas JH (1980) Representations of the body surface in postcentral parietal cortex of Macaca fascicularis. Journal of Comparative Neurology 192: 611–643.

Nolano M, Provitera V, Crisci C, et al. (2003) Quantification of myelinated endings and mechanoreceptors in human digital skin. Annals of Neurology 54: 197–205.

Pause M, Kunesch E, Binkofski F and Freund H‐J (1989) Sensorimotor disturbances in patients with lesions of the parietal cortex. Brain 112: 1599–1625.

Phillips JR, Johansson RS and Johnson KO (1992) Responses of human mechanoreceptive afferents to embossed dot arrays scanned across finger pad skin. Journal of Neuroscience 12: 827–839.

Pons TP, Garraghty PE, Ommaya AK, et al. (1991) Massive cortical reorganization after sensory deafferentation in adult macaques. Science 252: 1857–1860.

Pons TP, Garraghty PE and Mishkin M (1992) Serial and parallel processing of tactual information in somatosensory cortex of rhesus monkeys. Journal of Neurophysiology 68: 518–527.

Ranade SS, Woo SH, Dubin AE, et al. (2014) Piezo2 is the major transducer of mechanical forces for touch sensation in mice. Nature 516: 121–125.

Ranade SS, Syeda R and Patapoutian A (2015) Mechanically activated ion channels. Neuron 87: 1162–1179.

Ramachandran VS (1993) Behavioral and magnetoencephalographic correlates of plasticity in the adult human brain. Proceedings of the National Academy of Sciences of the USA 90: 10413–10420.

Recanzone GH, Merzenich MM, Jenkins WM, Grajski KA and Dinse HR (1992) Topographic reorganization of the hand representation in cortical area 3b of owl monkeys trained in a frequency discrimination task. Journal of Neurophysiology 67: 1031–1056.

Robinson CJ and Burton H (1980) Somatic submodality distribution within the second somatosensory (SII), 7b, retroinsular, postauditory and granular insular cortical areas of M. fascicularis. Journal of Comparative Neurology 192: 93–108.

Romo R, Hernandez A, Zainos A, Lemus L and Brody CD (2002) Neuronal correlates of decision‐making in secondary somatosensory cortex. Nature Neuroscience 5: 1217–1235.

Sathian K, Goodwin AW, John KT and Darian Smith I (1989) Perceived roughness of a grating: correlation with responses of mechanoreceptive afferents innervating the monkey's fingerpad. Journal of Neuroscience 9: 1273–1279.

Sripati AP, Yoshioka T, Denchev P, Hsiao SS and Johnson KO (2006) Spatiotemporal receptive fields of peripheral afferents and cortical area 3b and 1 neurons in the primate somatosensory system. Journal of Neuroscience 26: 2101–2114.

Sur M, Merzenich M and Kaas JH (1980) Magnification, receptive‐field area, and ‘hypercolumn’ size in areas 3b and 1 of somatosensory cortex in owl monkeys. Journal of Neurophysiology 44: 295–311.

Sur M, Wall JT and Kaas JH (1984) Modular distribution of neurons with slowly adapting and rapidly adapting responses in area 3b of somatosensory cortex in monkeys. Journal of Neurophysiology 56: 598–622.

Talbot WH, Darian‐Smith I, Kornhuber HH and Mountcastle VB (1968) The sense of flutter‐vibration: comparison of the human capacity with response patterns of mechanoreceptive afferents from the monkey hand. Journal of Neurophysiology 31: 301–334.

Ungerleider LG and Mishkin M (1982) Two cortical visual systems. In: Ingle DG, Goodale MA and Mansfield RJW (eds) Analysis of Visual Behavior, pp 549–586. MIT Press: Cambridge, MA.

Wang L, Zhou H, Zhang M, et al. (2019) Structure and mechanogating of the mammalian tactile channel PIEZO2. Nature 573: 225–229.

Warren S, Hamalainen HA and Gardner EP (1986) Objective classification of motion‐ and direction‐sensitive neurons in primary somatosensory cortex of awake monkeys. Journal of Neurophysiology 56: 598–622.

Wellnitz SA, Lesniak DR, Gerling GJ and Lumpkin EA (2010) The regularity of sustained firing reveals two populations of slowly adapting touch receptors in mouse hairy skin. Journal of Neurophysiology 103: 3378–3388.

Woo SH, Ranade S, Weyer AD, et al. (2014) Piezo2 is required for Merkel‐cell mechanotransduction. Nature 509: 622–626.

Further Reading

Hyvärinen J (1982) Posterior parietal lobe of the primate brain. Physiological Reviews 62: 1060–1129.

Jones EG and Peters A (eds) (1986) Cerebral Cortex. Vol 5: Sensory‐Motor Areas and Aspects of Cortical Connectivity. Plenum Press: New York.

Jones EG and Pons TP (1998) Thalamic and brainstem contributions to large‐scale plasticity of primate somatosensory cortex. Science 282: 1121–1125.

Jones EG (2007) The Thalamus. Cambridge University Press: Cambridge.

Kaas JH and Gardner EP (eds) (2008) The Senses: A Comprehensive Reference. Vol 6: Somatosensation. Elsevier: Oxford.

Mountcastle VB (1995) The parietal system and some higher brain functions. Cerebral Cortex 5: 377–390.

Mountcastle VB (2005) The Sensory Hand. Neural Mechanisms of Somatic Sensation. Harvard University Press: Cambridge, MA.

Rizzolatti G and Matelli M (2003) Two different streams form the dorsal visual system: anatomy and functions. Experimental Brain Research 153: 146–157.

Zimmerman A, Bai L and Ginty DD (2014) The gentle touch receptors of mammalian skin. Science 346: 950–954.

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Gardner, Esther P(Aug 2020) Touch. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0029142]