Lateral inhibition

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Along the boundary between adjacent shades of grey in the Mach bands illusion, lateral inhibition makes the darker area falsely appear even darker and the lighter area falsely appear even lighter. Bandes de mach.PNG
Along the boundary between adjacent shades of grey in the Mach bands illusion, lateral inhibition makes the darker area falsely appear even darker and the lighter area falsely appear even lighter.

In neurobiology, lateral inhibition is the capacity of an excited neuron to reduce the activity of its neighbors. Lateral inhibition disables the spreading of action potentials from excited neurons to neighboring neurons in the lateral direction. This creates a contrast in stimulation that allows increased sensory perception. It is also referred to as lateral antagonism and occurs primarily in visual processes, but also in tactile, auditory, and even olfactory processing. [1] Cells that utilize lateral inhibition appear primarily in the cerebral cortex and thalamus and make up lateral inhibitory networks (LINs). [2] Artificial lateral inhibition has been incorporated into artificial sensory systems, such as vision chips, [3] hearing systems, [4] and optical mice. [5] [6] An often under-appreciated point is that although lateral inhibition is visualised in a spatial sense, it is also thought to exist in what is known as "lateral inhibition across abstract dimensions." This refers to lateral inhibition between neurons that are not adjacent in a spatial sense, but in terms of modality of stimulus. This phenomenon is thought to aid in colour discrimination. [7]

Contents

History

Optical illusion caused by lateral inhibition: the Hermann grid illusion Klam-HermannovaMrizka.jpg
Optical illusion caused by lateral inhibition: the Hermann grid illusion

The concept of neural inhibition (in motor systems) was well known to Descartes and his contemporaries. [8] Sensory inhibition in vision was inferred by Ernst Mach in 1865 as depicted in his mach band. [9] [10] Inhibition in single sensory neurons was discovered and investigated starting in 1949 by Haldan K. Hartline when he used logarithms to express the effect of Ganglion receptive fields. His algorithms also help explain the experiment conducted by David H. Hubel and Torsten Wiesel that expressed a variation of sensory processing, including lateral inhibition, within different species. [11]

In 1956, Hartline revisited this concept of lateral inhibition in horseshoe crab (Limulus polyphemus) eyes, during an experiment conducted with the aid of Henry G Wagner and Floyd Ratliff. Hartline explored the anatomy of ommatidia in the horseshoe crab because of their similar function and physiological anatomy to photoreceptors in the human eye. Also, they are much larger than photoreceptors in humans, which would make them much easier to observe and record. Hartline contrasted the response signal of the ommatidium when a single concentrated beam of light was directed at one receptor unit as opposed to three surrounding units. [12] He further supported his theory of lateral inhibition as the response signal of one unit was stronger when the surrounding units were not exposed to light. [13]

Sensory inhibition

A stimulus affecting all three neurons, but which affects B strongest or first, can be sharpened if B sends lateral signals to neighbors A and C not to fire, thereby inhibiting them. Lateral inhibition is used in vision to sharpen signals to the brain (pink arrow). Lateral Inhibition.png
A stimulus affecting all three neurons, but which affects B strongest or first, can be sharpened if B sends lateral signals to neighbors A and C not to fire, thereby inhibiting them. Lateral inhibition is used in vision to sharpen signals to the brain (pink arrow).

Georg von Békésy, in his book Sensory Inhibition, [14] explores a wide range of inhibitory phenomena in sensory systems, and interprets them in terms of sharpening.

Visual inhibition

Lateral inhibition increases the contrast and sharpness in visual response. This phenomenon already occurs in the mammalian retina. In the dark, a small light stimulus will enhance the different photoreceptors (rod cells). The rods in the center of the stimulus will transduce the "light" signal to the brain, whereas different rods on the outside of the stimulus will send a "dark" signal to the brain due to lateral inhibition from horizontal cells. This contrast between the light and dark creates a sharper image. (Compare unsharp masking in digital processing). This mechanism also creates the Mach band visual effect.

Visual lateral inhibition is the process in which photoreceptor cells aid the brain in perceiving contrast within an image. Electromagnetic light enters the eye by passing through the cornea, pupil, and the lens (optics). [15] It then bypasses the ganglion cells, amacrine cells, bipolar cells, and horizontal cells in order to reach the photoreceptors rod cells which absorb light. The rods become stimulated by the energy from the light and release an excitatory neural signal to the horizontal cells.

This excitatory signal, however, will only be transmitted by the rod cells in the center of the ganglion cell receptive field to ganglion cells because horizontal cells respond by sending an inhibitory signal to the neighboring rods to create a balance that allows mammals to perceive more vivid images. [16] The central rod will send the light signals directly to bipolar cells which in turn will relay the signal to the ganglion cells. [17] Amacrine cells also produce lateral inhibition to bipolar cells [18] and ganglion cells to perform various visual computations including image sharpening. [19] The final visual signals will be sent to the thalamus and cerebral cortex, where additional lateral inhibition occurs.

Tactile inhibition

Sensory information collected by the peripheral nervous system is transmitted to specific areas of the primary somatosensory area in the parietal cortex according to its origin on any given part of the body. For each neuron in the primary somatosensory area, there is a corresponding region of the skin that is stimulated or inhibited by that neuron. [20] The regions that correspond to a location on the somatosensory cortex are mapped by a homonculus. This corresponding region of the skin is referred to as the neuron's receptive field. The most sensitive regions of the body have the greatest representation in any given cortical area, but they also have the smallest receptive fields. The lips, tongue, and fingers are examples of this phenomenon. [20] Each receptive field is composed of two regions: a central excitatory region and a peripheral inhibitory region. One entire receptive field can overlap with other receptive fields, making it difficult to differentiate between stimulation locations, but lateral inhibition helps to reduce that overlap. [21] When an area of the skin is touched, the central excitatory region activates and the peripheral region is inhibited, creating a contrast in sensation and allowing sensory precision. The person can then pinpoint exactly which part of the skin is being touched. In the face of inhibition, only the neurons that are most stimulated and least inhibited will fire, so the firing pattern tends to concentrate at stimulus peaks. This ability becomes less precise as stimulation moves from areas with small receptive fields to larger receptive fields, e.g. moving from the fingertips to the forearm to the upper arm. [20]

Auditory inhibition

Similarities between sensory processes of the skin and the auditory system suggest lateral inhibition could play a role in auditory processing. The basilar membrane in the cochlea has receptive fields similar to the receptive fields of the skin and eyes. Also, neighboring cells in the auditory cortex have similar specific frequencies that cause them to fire, creating a map of sound frequencies similar to that of the somatosensory cortex. [22] Lateral inhibition in tonotopic channels can be found in the inferior colliculus and at higher levels of auditory processing in the brain. However, the role that lateral inhibition plays in auditory sensation is unclear. Some scientists found that lateral inhibition could play a role in sharpening spatial input patterns and temporal changes in sensation, [23] others propose it plays an important role in processing low or high tones.

Lateral inhibition is also thought to play a role in suppressing tinnitus. Tinnitus can occur when damage to the cochlea creates a greater reduction of inhibition than excitation, allowing neurons to become aware of sound without sound actually reaching the ear. [24] If certain sound frequencies that contribute to inhibition more than excitation are produced, tinnitus can be suppressed. [24] Evidence supports findings that high-frequency sounds are best for inhibition and therefore best for reducing some types of tinnitus.

In mustached bats, evidence supports the hypothesis that lateral inhibitory processes of the auditory system contribute to improved auditory information processing. Lateral inhibition would occur in the medial and dorsal divisions of the medial geniculate nucleus of mustached bats, along with positive feedback. [25] The exact functions of these regions are unclear, but they do contribute to selective auditory processing responses. These processes could play a role in auditory functioning of other mammals, such as cats.

Embryology

In embryology, the concept of lateral inhibition has been adapted to describe processes in the development of cell types. [26] Lateral inhibition is described as a part of the Notch signaling pathway, a type of cell–cell interaction. Specifically, during asymmetric cell division one daughter cell adopts a particular fate that causes it to be copy of the original cell and the other daughter cell is inhibited from becoming a copy. Lateral inhibition is well documented in flies, worms and vertebrates. [27] In all of these organisms, the transmembrane proteins Notch and Delta (or their homologues) have been identified as mediators of the interaction. Research has been more commonly associated with Drosophila, the fruit fly. [28] Synthetic embryologists have also been able to replicate lateral inhibition dynamics in developing bacterial colonies, [29] creating stripes and regular structures.

A neuroblast with slightly more Delta protein on its cell surface will inhibit its neighboring cells from becoming neurons. In flies, frogs, and chicks, Delta is found in those cells that will become neurons, while Notch is elevated in those cells that become the glial cells.

See also

Related Research Articles

<span class="mw-page-title-main">Perception</span> Interpretation of sensory information

Perception is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information or environment. All perception involves signals that go through the nervous system, which in turn result from physical or chemical stimulation of the sensory system. Vision involves light striking the retina of the eye; smell is mediated by odor molecules; and hearing involves pressure waves.

<span class="mw-page-title-main">Sensory nervous system</span> Part of the nervous system responsible for processing sensory information

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">Photoreceptor cell</span> Type of neuroepithelial cell

A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction. The great biological importance of photoreceptors is that they convert light into signals that can stimulate biological processes. To be more specific, photoreceptor proteins in the cell absorb photons, triggering a change in the cell's membrane potential.

<span class="mw-page-title-main">Stimulus (physiology)</span> Detectable change in the internal or external surroundings

In physiology, a stimulus is a detectable change in the physical or chemical structure of an organism's internal or external environment. The ability of an organism or organ to detect external stimuli, so that an appropriate reaction can be made, is called sensitivity (excitability). Sensory receptors can receive information from outside the body, as in touch receptors found in the skin or light receptors in the eye, as well as from inside the body, as in chemoreceptors and mechanoreceptors. When a stimulus is detected by a sensory receptor, it can elicit a reflex via stimulus transduction. An internal stimulus is often the first component of a homeostatic control system. External stimuli are capable of producing systemic responses throughout the body, as in the fight-or-flight response. In order for a stimulus to be detected with high probability, its level of strength must exceed the absolute threshold; if a signal does reach threshold, the information is transmitted to the central nervous system (CNS), where it is integrated and a decision on how to react is made. Although stimuli commonly cause the body to respond, it is the CNS that finally determines whether a signal causes a reaction or not.

Stimulus modality, also called sensory modality, is one aspect of a stimulus or what is perceived after a stimulus. For example, the temperature modality is registered after heat or cold stimulate a receptor. Some sensory modalities include: light, sound, temperature, taste, pressure, and smell. The type and location of the sensory receptor activated by the stimulus plays the primary role in coding the sensation. All sensory modalities work together to heighten stimuli sensation when necessary.

<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.

The receptive field, or sensory space, is a delimited medium where some physiological stimuli can evoke a sensory neuronal response in specific organisms.

<span class="mw-page-title-main">Retina bipolar cell</span> Type of neuron

As a part of the retina, bipolar cells exist between photoreceptors and ganglion cells. They act, directly or indirectly, to transmit signals from the photoreceptors to the ganglion cells.

<span class="mw-page-title-main">Medial geniculate nucleus</span>

The medial geniculate nucleus (MGN) or medial geniculate body (MGB) is part of the auditory thalamus and represents the thalamic relay between the inferior colliculus (IC) and the auditory cortex (AC). It is made up of a number of sub-nuclei that are distinguished by their neuronal morphology and density, by their afferent and efferent connections, and by the coding properties of their neurons. It is thought that the MGN influences the direction and maintenance of attention.

Intrinsically photosensitive retinal ganglion cells (ipRGCs), also called photosensitive retinal ganglion cells (pRGC), or melanopsin-containing retinal ganglion cells (mRGCs), are a type of neuron in the retina of the mammalian eye. The presence of ipRGCs was first suspected in 1927 when rodless, coneless mice still responded to a light stimulus through pupil constriction, This implied that rods and cones are not the only light-sensitive neurons in the retina. Yet research on these cells did not advance until the 1980s. Recent research has shown that these retinal ganglion cells, unlike other retinal ganglion cells, are intrinsically photosensitive due to the presence of melanopsin, a light-sensitive protein. Therefore, they constitute a third class of photoreceptors, in addition to rod and cone cells.

<span class="mw-page-title-main">Cochlear nucleus</span> Two cranial nerve nuclei of the human brainstem

The cochlear nuclear (CN) complex comprises two cranial nerve nuclei in the human brainstem, the ventral cochlear nucleus (VCN) and the dorsal cochlear nucleus (DCN). The ventral cochlear nucleus is unlayered whereas the dorsal cochlear nucleus is layered. Auditory nerve fibers, fibers that travel through the auditory nerve carry information from the inner ear, the cochlea, on the same side of the head, to the nerve root in the ventral cochlear nucleus. At the nerve root the fibers branch to innervate the ventral cochlear nucleus and the deep layer of the dorsal cochlear nucleus. All acoustic information thus enters the brain through the cochlear nuclei, where the processing of acoustic information begins. The outputs from the cochlear nuclei are received in higher regions of the auditory brainstem.

A topographic map is the ordered projection of a sensory surface, like the retina or the skin, or an effector system, like the musculature, to one or more structures of the central nervous system. Topographic maps can be found in all sensory systems and in many motor systems.

Complex cells can be found in the primary visual cortex (V1), the secondary visual cortex (V2), and Brodmann area 19 (V3).

<span class="mw-page-title-main">Bipolar neuron</span> Neuron with only one axon and one dendrite

A bipolar neuron, or bipolar cell, is a type of neuron that has two extensions. Many bipolar cells are specialized sensory neurons for the transmission of sense. As such, they are part of the sensory pathways for smell, sight, taste, hearing, touch, balance and proprioception. The other shape classifications of neurons include unipolar, pseudounipolar and multipolar. During embryonic development, pseudounipolar neurons begin as bipolar in shape but become pseudounipolar as they mature.

<span class="mw-page-title-main">Hypercomplex cell</span>

A hypercomplex cell is a type of visual processing neuron in the mammalian cerebral cortex. Initially discovered by David Hubel and Torsten Wiesel in 1965, hypercomplex cells are defined by the property of end-stopping, which is a decrease in firing strength with increasingly larger stimuli. The sensitivity to stimulus length is accompanied by selectivity for the specific orientation, motion, and direction of stimuli. For example, a hypercomplex cell may only respond to a line at 45˚ that travels upward. Elongating the line would result in a proportionately weaker response. Ultimately, hypercomplex cells can provide a means for the brain to visually perceive corners and curves in the environment by identifying the ends of a given stimulus.

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.

Sensory maps are areas of the brain which respond to sensory stimulation, and are spatially organized according to some feature of the sensory stimulation. In some cases the sensory map is simply a topographic representation of a sensory surface such as the skin, cochlea, or retina. In other cases it represents other stimulus properties resulting from neuronal computation and is generally ordered in a manner that reflects the periphery. An example is the somatosensory map which is a projection of the skin's surface in the brain that arranges the processing of tactile sensation. This type of somatotopic map is the most common, possibly because it allows for physically neighboring areas of the brain to react to physically similar stimuli in the periphery or because it allows for greater motor control.

Feature detection is a process by which the nervous system sorts or filters complex natural stimuli in order to extract behaviorally relevant cues that have a high probability of being associated with important objects or organisms in their environment, as opposed to irrelevant background or noise.

Robert Shapley is an American neurophysiologist, the Natalie Clews Spencer Professor of the Sciences at New York University, a professor in the Center for Neural Science and an associate member of the Courant Institute of Mathematical Sciences.

Surround suppression is where the relative firing rate of a neuron may under certain conditions decrease when a particular stimulus is enlarged. It has been observed in electrophysiology studies of the brain and has been noted in many sensory neurons, most notably in the early visual system. Surround suppression is defined as a reduction in the activity of a neuron in response to a stimulus outside its classical receptive field.

References

  1. ↑ Yantis, Steven (2014). Sensation and Perception. New York, NY: Worth Publishers. p. 77.
  2. ↑ Shamma, Shihab A. (3 January 1985). "Speech processing in the auditory system II: Lateral inhibition and the central processing of speech evoked activity in the auditory nerve". The Journal of the Acoustical Society of America. 78 (5): 1623. Bibcode:1985ASAJ...78.1622S. doi:10.1121/1.392800. PMID   3840813.
  3. ↑ Alireza Moini (2000). Vision Chips. Springer. ISBN   0-7923-8664-7.
  4. ↑ Christoph von der Malsburg et al. (editors) (1996). Artificial Neural Networks: ICANN 96. Springer. ISBN   3-540-61510-5.{{cite book}}: |author= has generic name (help)
  5. ↑ Alireza Moini (1997). "Vision Chips" (PDF).
  6. ↑ Richard F. Lyon (1981), "The Optical Mouse and an Architectural Methodology for Smart Digital Sensors" (PDF), Xerox PARC report VLSI-81-1
  7. ↑ RHS Carpenter (1997). Neurophysiology. Arnold, London.
  8. ↑ Marcus Jacobson (1993). Foundations of neuroscience (2nd ed.). Springer. p. 277. ISBN   978-0-306-44540-8.
  9. ↑ Yantis, Steven (11 February 2013). Sensation and perception. New York, NY: Worth Publishers. ISBN   978-0-7167-5754-2.
  10. ↑ G. A. Orchard; W. A. Phillips (1991). Neural computation: a beginner's guide. Taylor & Francis. p. 26. ISBN   978-0-86377-235-1.
  11. ↑ Shaw, ed. by Gordon L.; Gunther Palm (1988). Brain theory: Reprint Volume (Reprinted. ed.). Singapore [u.a.]: World Scientific. ISBN   9971504847.{{cite book}}: |first= has generic name (help)
  12. ↑ Goldstein, E. Bruce (2007). Sensation and perception (7. ed.). Wadsworth: Thomson. ISBN   9780534558109.
  13. ↑ Hartline, Haldan K.; Henry G Wagner; Floyd Ratliff (20 May 1956). "Inhibition in the eye of Limulus". The Journal of General Physiology. 5. 39 (5): 651–671. doi: 10.1085/jgp.39.5.651 . PMC   2147566 . PMID   13319654.
  14. ↑ Georg Von Békésy (1967). Sensory Inhibition. Princeton University Press.
  15. ↑ Heller, Morton A.; Edouard Gentaz (Oct 2013). Psychology of Touch and Blindness. Taylor and Francis. pp. 20–21. ISBN   9781134521593.
  16. ↑ Yantis, Stevens (2014). Sensation and perception. Worth Publishers.
  17. ↑ Levine, Michael W. (2000). Levine & Shefner's fundamentals of sensation and perception (3rd ed.). Oxford, England: Oxford University Press. ISBN   9780198524670.
  18. ↑ Tanaka M, Tachibana M (15 August 2013). "Independent control of reciprocal and lateral inhibition at the axon terminal of retinal bipolar cells". J Physiol. 591 (16): 3833–51. doi:10.1113/jphysiol.2013.253179. PMC   3764632 . PMID   23690563.
  19. ↑ Roska B, Nemeth E, Orzo L, Werblin FS (1 March 2000). "Three levels of lateral inhibition: A space-time study of the retina of the tiger salamander". J Neurosci. 20 (5): 1941–51. doi:10.1523/JNEUROSCI.20-05-01941.2000. PMC   6772932 . PMID   10684895.
  20. 1 2 3 Heller, Morton A. (2013). Psychology of Touch and Blindness. New York, NY: Taylor and Francis. p. 20.
  21. ↑ Fox, Kevin (2008). Barrel Cortex . New York: Cambridge University Press. p.  127. ISBN   9780521852173.
  22. ↑ Bernstein, Douglas A. (2008). Psychology . Boston, MA: Houghton Mifflin Company. p.  118. ISBN   9780618824311.
  23. ↑ Shamma, Shihab A. (3 January 1985). "Speech processing in the auditory system II: Lateral inhibition and the central processing of speech evoked activity in the auditory nerve". The Journal of the Acoustical Society of America. 78 (5): 1622–32. Bibcode:1985ASAJ...78.1622S. doi:10.1121/1.392800. PMID   3840813.
  24. 1 2 Moller, Aage R. (2011). Textbook of Tinnitus . New York, NY: Springer. p.  96.
  25. ↑ Gallagher, Michela; Irving Weiner; Randy Nelson (2003). "Biological Psychology". Handbook of Psychology. 3: 84.
  26. ↑ Alfred Gierer; Hans Meinhardt (1974). Donald S. Cohen (ed.). "Biological Pattern Formation Involving Lateral Inhibition". Some Mathematical Questions in Biology VI: Mathematical Aspects of Chemical and Biochemical Problems and Quantum Chemistry. American Mathematical Society. 7. ISBN   978-0-8218-1328-7.
  27. ↑ Haddon, C.; L. Smithers; S. Schneider-Maunoury; T. Coche; D. Henrique; J. Lewis (January 1998). "Multiple delta genes and lateral inhibition in zebrafish primary neurogenesis". Development. 125 (3): 359–370. doi:10.1242/dev.125.3.359. PMID   9425132 . Retrieved 7 December 2013.
  28. ↑ Jorg, Reichrath (2012). Notch Signaling in Embryology and Cancer. Springer. ISBN   9781461408994.
  29. ↑ Duran-Nebreda, Salva; Pla, Jordi; Vidiella, Blai; Piñero, Jordi; Conde-Pueyo, Nuria; Solé, Ricard (2021-01-15). "Synthetic Lateral Inhibition in Periodic Pattern Forming Microbial Colonies". ACS Synthetic Biology. 10 (2): 277–285. doi:10.1021/acssynbio.0c00318. ISSN   2161-5063. PMC   8486170 . PMID   33449631.
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