Tegula (insect anatomy)

Last updated

A tegula is a small sclerite situated above the base of the costal vein in the wings of various insects such as Orthoptera, Lepidoptera, Hymenoptera, Diptera, and Auchenorrhyncha, and attached to the antero-lateral portion of the mesonotum. [1] It is densely innervated, with sensory bristles, campaniform sensilla, as well as a chordotonal organ in some species. [2]

The tegula in locusts is a model system for studying the role of feedback from mechanoreceptors during movement. [3] [4] [5] In locusts, the tegula directly controls flight muscles. The motor neurons that control the activation of wing elevator muscles are phase-locked to the neurons that innervate the tegula such that when the tegula is electrically stimulated the elevator muscles initiate an upstroke. [6] When the tegula is removed, locust flight is clumsy and disordered at first but most animals adapt, suggesting the use of other mechanoreceptors to control flight. [7] [8] [9]

The tegula system is also a model for studying the role of neuromodulation for state-dependent motor control. Neural signals from the tegula only initiate wing muscle contraction when the animal is in flight (or fictive flight) due to endogenous release of the neuromodulator octopamine. [10] This mechanism ensures that the animal does not initiate a wing stroke if the bristles are deflected by wind as the animal is walking.

The tegula is labeled f on this chalcid. Click for an uncropped version. Chalcid thorax.jpg
The tegula is labeled f on this chalcid. Click for an uncropped version.

Related Research Articles

<span class="mw-page-title-main">Motor neuron</span> Nerve cell sending impulse to muscle

A motor neuron is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly or indirectly control effector organs, mainly muscles and glands. There are two types of motor neuron – upper motor neurons and lower motor neurons. Axons from upper motor neurons synapse onto interneurons in the spinal cord and occasionally directly onto lower motor neurons. The axons from the lower motor neurons are efferent nerve fibers that carry signals from the spinal cord to the effectors. Types of lower motor neurons are alpha motor neurons, beta motor neurons, and gamma motor neurons.

In biology, a reflex, or reflex action, is an involuntary, unplanned sequence or action and nearly instantaneous response to a stimulus.

<span class="mw-page-title-main">Muscle spindle</span> Innervated muscle structure involved in reflex actions and proprioception

Muscle spindles are stretch receptors within the body of a skeletal muscle that primarily detect changes in the length of the muscle. They convey length information to the central nervous system via afferent nerve fibers. This information can be processed by the brain as proprioception. The responses of muscle spindles to changes in length also play an important role in regulating the contraction of muscles, for example, by activating motor neurons via the stretch reflex to resist muscle stretch.

<span class="mw-page-title-main">Grey column</span>

The grey column refers to a somewhat ridge-shaped mass of grey matter in the spinal cord. This presents as three columns: the anterior grey column, the posterior grey column, and the lateral grey column, all of which are visible in cross-section of the spinal cord.

A mechanoreceptor, also called mechanoceptor, is a sensory receptor that responds to mechanical pressure or distortion. Mechanoreceptors are innervated by sensory neurons that convert mechanical pressure into electrical signals that, in animals, are sent to the central nervous system.

<span class="mw-page-title-main">Interneuron</span> Neurons that are not motor or sensory

Interneurons are neurons that connect to brain regions, i.e. not direct motor neurons or sensory neurons. Interneurons are the central nodes of neural circuits, enabling communication between sensory or motor neurons and the central nervous system (CNS). They play vital roles in reflexes, neuronal oscillations, and neurogenesis in the adult mammalian brain.

<span class="mw-page-title-main">Caridoid escape reaction</span> Innate escape mechanism by crustaceans

The caridoid escape reaction, also known as lobstering or tail-flipping, refers to an innate escape mechanism in marine and freshwater crustaceans such as lobsters, krill, shrimp and crayfish.

Robot locomotion is the collective name for the various methods that robots use to transport themselves from place to place.

Central pattern generators (CPGs) are self-organizing biological neural circuits that produce rhythmic outputs in the absence of rhythmic input. They are the source of the tightly-coupled patterns of neural activity that drive rhythmic and stereotyped motor behaviors like walking, swimming, breathing, or chewing. The ability to function without input from higher brain areas still requires modulatory inputs, and their outputs are not fixed. Flexibility in response to sensory input is a fundamental quality of CPG-driven behavior. To be classified as a rhythmic generator, a CPG requires:

  1. "two or more processes that interact such that each process sequentially increases and decreases, and
  2. that, as a result of this interaction, the system repeatedly returns to its starting condition."
<span class="mw-page-title-main">Insect flight</span> Mechanisms and evolution of insect flight

Insects are the only group of invertebrates that have evolved wings and flight. Insects first flew in the Carboniferous, some 300 to 350 million years ago, making them the first animals to evolve flight. Wings may have evolved from appendages on the sides of existing limbs, which already had nerves, joints, and muscles used for other purposes. These may initially have been used for sailing on water, or to slow the rate of descent when gliding.

<span class="mw-page-title-main">Campaniform sensilla</span> Class of mechanoreceptors found in insects

Campaniform sensilla are a class of mechanoreceptors found in insects, which respond to local stress and strain within the animal's cuticle. Campaniform sensilla function as proprioceptors that detect mechanical load as resistance to muscle contraction, similar to mammalian Golgi tendon organs. Sensory feedback from campaniform sensilla is integrated in the control of posture and locomotion.

<span class="mw-page-title-main">Alpha motor neuron</span>

Alpha (α) motor neurons (also called alpha motoneurons), are large, multipolar lower motor neurons of the brainstem and spinal cord. They innervate extrafusal muscle fibers of skeletal muscle and are directly responsible for initiating their contraction. Alpha motor neurons are distinct from gamma motor neurons, which innervate intrafusal muscle fibers of muscle spindles.

<span class="mw-page-title-main">Torkel Weis-Fogh</span> Danish insect flight expert (1922–1975)

Torkel Weis-Fogh was a Danish zoologist and Professor at the University of Cambridge and the University of Copenhagen. He is best known for his contributions to the understanding of insect flight, especially the clap and fling mechanism used by very small insects. James Lighthill named this "the Weis-Fogh mechanism of lift generation".

The medial giant interneuron (MG) is an interneuron in the abdominal nerve cord of crayfish. It is part of the system that controls the caridoid escape reaction of crayfish, clawed lobsters, and other decapod crustaceans. Crayfish have a pair of medial giants running the length of the entire animal, and are the largest neurons in the animal.

The Golgi tendon reflex (also called inverse stretch reflex, autogenic inhibition, tendon reflex) is an inhibitory effect on the muscle resulting from the muscle tension stimulating Golgi tendon organs (GTO) of the muscle, and hence it is self-induced. The reflex arc is a negative feedback mechanism preventing too much tension on the muscle and tendon. When the tension is extreme, the inhibition can be so great it overcomes the excitatory effects on the muscle's alpha motoneurons causing the muscle to suddenly relax. This reflex is also called the inverse myotatic reflex, because it is the inverse of the stretch reflex.

<span class="mw-page-title-main">Proprioception</span> Sense of self-movement, force, and body position

Proprioception, also called kinaesthesia, is the sense of self-movement, force, and body position.

Ultrasound avoidance is an escape or avoidance reflex displayed by certain animal species that are preyed upon by echolocating predators. Ultrasound avoidance is known for several groups of insects that have independently evolved mechanisms for ultrasonic hearing. Insects have evolved a variety of ultrasound-sensitive ears based upon a vibrating tympanic membrane tuned to sense the bat's echolocating calls. The ultrasonic hearing is coupled to a motor response that causes evasion of the bat during flight.

<span class="mw-page-title-main">Spinal interneuron</span> Interneuron relaying signals between sensory and motor neurons in the spinal cord

A spinal interneuron, found in the spinal cord, relays signals between (afferent) sensory neurons, and (efferent) motor neurons. Different classes of spinal interneurons are involved in the process of sensory-motor integration. Most interneurons are found in the grey column, a region of grey matter in the spinal cord.

<span class="mw-page-title-main">Golgi tendon organ</span> Proprioceptive sensory receptor organ that senses changes in muscle tension

The Golgi tendon organ (GTO) is a proprioceptor – a type of sensory receptor that senses changes in muscle tension. It lies at the interface between a muscle and its tendon known as the musculotendinous junction also known as the myotendinous junction. It provides the sensory component of the Golgi tendon reflex.

References

  1. ↑ Fischer, Wolf and Büschges. "The locust tegula: kinematic parameters and activity pattern during the wing stroke". Journal of Experimental Biology . Retrieved 2010-08-31.
  2. ↑ Fudalewicz-Niemczyk, Władysława (1963). L'innervation et les organes sensoriels des ailes des Diptères et comparaison avec l'innervation des ailes d'insectes d'autres ordres.
  3. ↑ Ramirez, J. M., & Pearson, K. G. (1993). Alteration of bursting properties in interneurons during locust flight. Journal of neurophysiology, 70(5), 2148-2160.
  4. ↑ Pearson, K. G. and Wolf, H. Connections of hindwing tegulae with flight neurones in the locust, Locusta migratoria. J. Exp. Biol. 135:381-409, 1988
  5. ↑ Wolf, H. "The Locust Tegula: significance for flight rhythm generation, wing movement control and aerodynamic force production." Journal of Experimental Biology 182.1 (1993): 229-253.
  6. ↑ Wolf, H. "The Locust Tegula: significance for flight rhythm generation, wing movement control and aerodynamic force production." Journal of Experimental Biology 182.1 (1993): 229-253.
  7. ↑ Recovery of the flight system following ablation of the tegulae in immature adult locusts, C Gee, R Robertson, Journal of Experimental Biology 1996 199: 1395-1403.
  8. ↑ Kien, J., Altman, J.S. Connections of the locust wing tegulae with metathoracic flight motoneurons. J. Comp. Physiol. 133, 299–310 (1979). https://doi.org/10.1007/BF00661132
  9. ↑ Büschges, A., & Pearson, K. G. (1991). Adaptive modifications in the flight system of the locust after the removal of wing proprioceptors. Journal of Experimental Biology, 157(1), 313-333.
  10. ↑ Ramirez, J. M., & Pearson, K. G. (1991). Octopaminergic modulation of interneurons in the flight system of the locust. Journal of Neurophysiology, 66(5), 1522-1537.


This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.