Thermoception

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In physiology, thermoception or thermoreception is the sensation and perception of temperature, or more accurately, temperature differences inferred from heat flux. It deals with a series of events and processes required for an organism to receive a temperature stimulus, convert it to a molecular signal, and recognize and characterize the signal in order to trigger an appropriate defense response.

Contents

Thermoception in larger animals is mainly done in the skin; mammals have at least two types. The details of how temperature receptors work are still being investigated. Ciliopathy is associated with decreased ability to sense heat; thus cilia may aid in the process. [1] Transient receptor potential channels (TRP channels) [lower-alpha 1] are believed to play a role in many species in sensation of hot, cold, and pain. Vertebrates have at least two types of sensor: those that detect heat and those that detect cold. [4]

In animals

Positions of the pit organs (arrowed in red) on a python, relative to its nostril (black arrow) Pit organs of a python.jpg
Positions of the pit organs (arrowed in red) on a python, relative to its nostril (black arrow)

In snakes

A particularly specialized form of thermoception is used by Crotalinae (pit viper) and Boidae (boa) snakes, which can effectively see the infrared radiation emitted by hot objects. [5] The snakes' face has a pair of holes, or pits, lined with temperature sensors. The sensors indirectly detect infrared radiation by its heating effect on the skin inside the pit. They can work out which part of the pit is hottest, and therefore the direction of the heat source, which could be a warm-blooded prey animal. By combining information from both pits, the snake can also estimate the distance of the object.

In bats and other mammals

The Common vampire bat has specialized infrared sensors in its nose-leaf. [6] [7] Vampire bats are the only mammals that feed exclusively on blood. The infrared sense enables Desmodus to localize homeothermic (warm-blooded) animals (cattle, horses, wild mammals) within a range of about 10 to 15 cm. This infrared perception is possibly used in detecting regions of maximal blood flow on targeted prey.

A 2020 paper [8] has demonstrated that dogs, like vampire bats, can detect weak thermal radiation with their rhinaria (noses).

In insects

Other animals with specialized heat detectors are forest fire seeking beetles ( Melanophila acuminata ), which lay their eggs in conifers freshly killed by forest fires. Darkly pigmented butterflies Pachliopta aristolochiae and Troides rhadamantus use specialized heat detectors to avoid damage while basking. The blood sucking bugs Triatoma infestans may also have a specialised thermoception organ.

In humans

In humans, temperature sensation from thermoreceptors [lower-alpha 1] enters the spinal cord along the axons of Lissauer's tract that synapse on second order neurons in grey matter of the dorsal horn. The axons of these second order neurons then decussate, joining the spinothalamic tract as they ascend to neurons in the ventral posterolateral nucleus of the thalamus. A study in 2017 shows that the thermosensory information passes to the lateral parabrachial nucleus rather than to the thalamus and this drives thermoregulatory behaviour. [9] [10]

Nobel Prize 2021

The Nobel Prize in Physiology or Medicine in 2021 was attributed to David Julius (professor at the University of California, San Francisco, USA) and Ardem Patapoutian (neuroscience professor at Scripps Research in La Jolla, California, USA) "for their discovery of receptors for temperature and touch". [2] [3]

See also

Notes

  1. 1 2 The TRPV1 and TRPM8 receptors play key roles in the perception of heat and cold. [2] [3]

Related Research Articles

In physiology, nociception, also nocioception; from Latin nocere 'to harm/hurt') is the sensory nervous system's process of encoding noxious stimuli. It deals with a series of events and processes required for an organism to receive a painful stimulus, convert it to a molecular signal, and recognize and characterize the signal to trigger an appropriate defensive response.

<span class="mw-page-title-main">Trigeminal nerve</span> Cranial nerve responsible for the faces senses and motor functions

In neuroanatomy, the trigeminal nerve (lit. triplet nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for sensation in the face and motor functions such as biting and chewing; it is the most complex of the cranial nerves. Its name (trigeminal, from Latin tri- 'three', and -geminus 'twin') derives from each of the two nerves (one on each side of the pons) having three major branches: the ophthalmic nerve (V1), the maxillary nerve (V2), and the mandibular nerve (V3). The ophthalmic and maxillary nerves are purely sensory, whereas the mandibular nerve supplies motor as well as sensory (or "cutaneous") functions. Adding to the complexity of this nerve is that autonomic nerve fibers as well as special sensory fibers (taste) are contained within it.

<span class="mw-page-title-main">Thermography</span> Infrared imaging used to reveal temperature

Infrared thermography (IRT), thermal video and/or thermal imaging, is a process where a thermal camera captures and creates an image of an object by using infrared radiation emitted from the object in a process, which are examples of infrared imaging science. Thermographic cameras usually detect radiation in the long-infrared range of the electromagnetic spectrum and produce images of that radiation, called thermograms. Since infrared radiation is emitted by all objects with a temperature above absolute zero according to the black body radiation law, thermography makes it possible to see one's environment with or without visible illumination. The amount of radiation emitted by an object increases with temperature; therefore, thermography allows one to see variations in temperature. When viewed through a thermal imaging camera, warm objects stand out well against cooler backgrounds; humans and other warm-blooded animals become easily visible against the environment, day or night. As a result, thermography is particularly useful to the military and other users of surveillance cameras.

<span class="mw-page-title-main">Sensory nervous system</span> Part of the nervous system

The sensory nervous system is a part of the nervous system responsible for processing sensory information. A sensory system consists of sensory neurons, neural pathways, and parts of the brain involved in sensory perception and interoception. Commonly recognized sensory systems are those for vision, hearing, touch, taste, smell, balance and visceral sensation. Sense organs are transducers that convert data from the outer physical world to the realm of the mind where people interpret the information, creating their perception of the world around them.

<span class="mw-page-title-main">Vampire bat</span> Species of bat

Vampire bats, members of the subfamily Desmodontinae, are leaf-nosed bats currently found in Central and South America. Their food source is the blood of other animals, a dietary trait called hematophagy. Three extant bat species feed solely on blood: the common vampire bat, the hairy-legged vampire bat, and the white-winged vampire bat. Two extinct species of the genus Desmodus have been found in North America.

<span class="mw-page-title-main">Nociceptor</span> Sensory neuron that detects pain

A nociceptor is a sensory neuron that responds to damaging or potentially damaging stimuli by sending "possible threat" signals to the spinal cord and the brain. The brain creates the sensation of pain to direct attention to the body part, so the threat can be mitigated; this process is called nociception.

The Crotalinae, commonly known as pit vipers, or pit adders, are a subfamily of vipers found in Eurasia and the Americas. Like all other vipers, they are venomous. They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on both sides of the head. Currently, 23 genera and 155 species are recognized: These are also the only viperids found in the Americas. The groups of snakes represented here include rattlesnakes, lanceheads, and Asian pit vipers. The type genus for this subfamily is Crotalus, of which the type species is the timber rattlesnake, C. horridus.

<span class="mw-page-title-main">Sensory neuron</span> Nerve cell that converts environmental stimuli into corresponding internal stimuli

Sensory neurons, also known as afferent neurons, are neurons in the nervous system, that convert a specific type of stimulus, via their receptors, into action potentials or graded receptor potentials. This process is called sensory transduction. The cell bodies of the sensory neurons are located in the dorsal ganglia of the spinal cord.

<span class="mw-page-title-main">Far infrared</span> Light with 15-1000 μm wavelength

Far infrared (FIR) refers to a specific range within the infrared spectrum of electromagnetic radiation. It encompasses radiation with wavelengths ranging from 15 μm (micrometers) to 1 mm, which corresponds to a frequency range of approximately 20 THz to 300 GHz. This places far infrared radiation within the CIE IR-B and IR-C bands. The longer wavelengths of the FIR spectrum overlap with a range known as terahertz radiation. Different sources may use different boundaries to define the far infrared range. For instance, astronomers often define it as wavelengths between 25 μm and 350 μm. Infrared photons possess significantly lower energy than photons in the visible light spectrum, with tens to hundreds of times less energy.

<span class="mw-page-title-main">TRPV2</span> Protein-coding gene in the species Homo sapiens

Transient receptor potential cation channel subfamily V member 2 is a protein that in humans is encoded by the TRPV2 gene. TRPV2 is a nonspecific cation channel that is a part of the TRP channel family. This channel allows the cell to communicate with its extracellular environment through the transfer of ions, and responds to noxious temperatures greater than 52 °C. It has a structure similar to that of potassium channels, and has similar functions throughout multiple species; recent research has also shown multiple interactions in the human body.

<span class="mw-page-title-main">TRPV3</span> Protein-coding gene in the species Homo sapiens

Transient receptor potential cation channel, subfamily V, member 3, also known as TRPV3, is a human gene encoding the protein of the same name.

<span class="mw-page-title-main">Infrared sensing in snakes</span>

The ability to sense infrared thermal radiation evolved independently in two different groups of snakes, one consisting of the families Boidae (boas) and Pythonidae (pythons), the other of the family Crotalinae. What is commonly called a pit organ allows these animals to essentially "see" radiant heat at wavelengths between 5 and 30 μm. The more advanced infrared sense of pit vipers allows these animals to strike prey accurately even in the absence of light, and detect warm objects from several meters away. It was previously thought that the organs evolved primarily as prey detectors, but recent evidence suggests that it may also be used in thermoregulation and predator detection, making it a more general-purpose sensory organ than was supposed.

Infrared vision is the capability of biological or artificial systems to detect infrared radiation. The terms thermal vision and thermal imaging, are also commonly used in this context since infrared emissions from a body are directly related to their temperature: hotter objects emit more energy in the infrared spectrum than colder ones.

A sense is a biological system used by an organism for sensation, the process of gathering information about the world through the detection of stimuli. Although in some cultures five human senses were traditionally identified as such, many more are now recognized. Senses used by non-human organisms are even greater in variety and number. During sensation, sense organs collect various stimuli for transduction, meaning transformation into a form that can be understood by the brain. Sensation and perception are fundamental to nearly every aspect of an organism's cognition, behavior and thought.

<span class="mw-page-title-main">David Julius</span> American physiologist and Nobel laureate 2021

David Jay Julius is an American physiologist and Nobel Prize laureate known for his work on molecular mechanisms of pain sensation and heat, including the characterization of the TRPV1 and TRPM8 receptors that detect capsaicin, menthol, and temperature. He is a professor at the University of California, San Francisco.

<span class="mw-page-title-main">Haller's organ</span> Sensory organ on the front legs of ticks

Haller's organ is a complex sensory organ possessed by hard and soft ticks. Not found outside of Acari, it is proposed to function like the chemosensation of insect antennae, but is structurally different. Ticks, being obligate parasites, must find a host in order to survive. Bloodmeals are necessary for completion of the life cycle, including reproduction and ontogenetic development. First described in 1881, it was named for its discoverer, Haller. While Haller initially proposed it was involved in auditory sensation, this was rejected in favor of olfactory sensation by 1905. This theory was supported by Lee's behavioral studies as early as 1948.

<span class="mw-page-title-main">Infrared sensing in vampire bats</span>

Vampire bats have developed a specialized system using infrared-sensitive receptors on their nose-leaf to prey on homeothermic (warm-blooded) vertebrates. Trigeminal nerve fibers that innervate these IR-sensitive receptors may be involved in detection of infrared thermal radiation emitted by their prey. This may aid bats in locating blood-rich areas on their prey. In addition, neuroanatomical and molecular research has suggested possible similarities of IR-sensing mechanisms between vampire bats and IR-sensitive snakes. Infrared sensing in vampire bats has not yet been hypothesized to be image forming, as it was for IR-sensitive snakes. While the literature on IR-sensing in vampire bats is thin, progress continues to be made in this field to identify how vampire bats can sense and use infrared thermal radiation.

The parabrachial nuclei, also known as the parabrachial complex, are a group of nuclei in the dorsolateral pons that surrounds the superior cerebellar peduncle as it enters the brainstem from the cerebellum. They are named from the Latin term for the superior cerebellar peduncle, the brachium conjunctivum. In the human brain, the expansion of the superior cerebellar peduncle expands the parabrachial nuclei, which form a thin strip of grey matter over most of the peduncle. The parabrachial nuclei are typically divided along the lines suggested by Baxter and Olszewski in humans, into a medial parabrachial nucleus and lateral parabrachial nucleus. These have in turn been subdivided into a dozen subnuclei: the superior, dorsal, ventral, internal, external and extreme lateral subnuclei; the lateral crescent and subparabrachial nucleus along the ventrolateral margin of the lateral parabrachial complex; and the medial and external medial subnuclei

<span class="mw-page-title-main">Ardem Patapoutian</span> Molecular biologist, neuroscientist, and Nobel laureate 2021

Ardem Patapoutian is an Lebanese-American molecular biologist, neuroscientist, and Nobel Prize laureate of Armenian descent. He is known for his work in characterizing the PIEZO1, PIEZO2, and TRPM8 receptors that detect pressure, menthol, and temperature. Patapoutian is a neuroscience professor and Howard Hughes Medical Institute investigator at Scripps Research in La Jolla, California. In 2021, he won the Nobel Prize in Physiology or Medicine jointly with David Julius.

The 2021 Nobel Prize in Physiology or Medicine was jointly awarded to the American physiologist David Julius and Armenian-American neuroscientist Ardem Patapoutian "for the discovery of receptors for temperature and touch." During the award ceremony on December 10, 2021, Nobel Assembly at Karolinska Institutet member Patrik Ernfors expressed:

"The 2021 Nobel Prize laureates have explained fundamental mechanisms underpinning how we sense the world within and around us. Our temperature and touch sensors are used all the time in every day of our lives. They continuously keep us updated about our environment, and without them even the simplest of our daily tasks would be impossible to perform."

References

  1. "Can You Feel The Heat? Your Cilia Can". 2007-10-22. Retrieved 2011-09-03.
  2. 1 2 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
  3. 1 2 "The Nobel Prize in Physiology or Medicine" (PDF). Nobel Foundation. Retrieved 2021-10-04.
  4. Johnson, JI (2008). Kaas, JH; Gardner, EP (eds.). 6.16 Specialized Somatosensory Systems. Vol. 6: Somatosensation. Elsevier. 6.16.2 Thermal Sensory Systems, pp. 332-335.{{cite book}}: |work= ignored (help)
  5. E. A. Newman, P. H. Hartline (1982). The Infrared ‘vision’ of snakes. Scientific American 20:116-127.
  6. L. Kürten, U. Schmidt, K. Schäfer (1984): Warm and Cold Receptors in the Nose of the Vampire Bat, Desmodus rotundus. Naturwissenschaften 71:327-28.
  7. E. O. Gracheva, J. F. Codero-Morales, J. A. González-Carcaía, N. T. Ingolia, C. Manno, C. I. Aranguren, J. S. Weissman, D. Julius (2011). Ganglion-specific splicing of TRPV1 underlies infrared sensation in vampire bats. Nature 476:88-91.
  8. Bálint, A., Andics, A., Gácsi, M. et al. Dogs can sense weak thermal radiation. Sci Rep 10, 3736 (2020).
  9. Nakamura, K (2018). "Thermoregulatory behavior and its central circuit mechanism-What thermosensory pathway drives it?]". Clinical Calcium. 28 (1): 65–72. PMID   29279428.
  10. Yahiro, T; Kataoka, N; Nakamura, Y; Nakamura, K (10 July 2017). "The lateral parabrachial nucleus, but not the thalamus, mediates thermosensory pathways for behavioural thermoregulation". Scientific Reports. 7 (1): 5031. Bibcode:2017NatSR...7.5031Y. doi:10.1038/s41598-017-05327-8. PMC   5503995 . PMID   28694517.