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Single sensillum recording (SSR) is a form of extracellular electrophysiology. This technique measures action potentials, generated from olfactory sensory neurons (OSNs), through a single sensilla on an insects' antennae. [1] These sensillum are hair-like structures that protrude through the cuticle as well as several other auxiliary and sensory cells. [2]
This method is often utilized if more quantitative results are desired, as the recordings produced have the ability to test and demonstrate the sensitivity and selectivity of individual OSNs, providing a technique for mapping the receptiveness of olfactory receptor proteins within the OSNs. It is also often combined with other techniques, such as gas chromatography, sensillum incision, diffusion, or microinjection. [1]
Some applications for this technique include testing pheromone sensitivity, testing reactions to volatile compounds in the environment, and reactivity to chemical cues from other organisms.
The test insect is mounted within a pipette tip, with the head slightly protruding from the tip. The main goal of this is to restrain the insect and prevent any movement from interfering with the recording quality. The pipette tip containing the insect is fixed to a microscope slide facing upwards, then the antennae are fixed using a glass microcapillary, wax, or tape; manipulating it until the desired orientation is attained. [3]
In order to record, a location as close to the sensilla (usually the eye) is penetrated with a ground electrode. Then, another is inserted into the cuticle of the sensilla. These electrodes are typically made of tungsten or glass and are chemically sharpened to ensure precise penetration of their target locations. Initial contact will often result in an increase in signal noise, acting as a signal that the prepared insect is both alive and properly grounded. At this point, action potentials should be easy to distinguish from background noise; however, if the signal strength is weak one can replace the electrodes. [1] Alternatively, one may test using different sensilla. [1]
Electrophysiology is the branch of physiology that studies the electrical properties of biological cells and tissues. It involves measurements of voltage changes or electric current or manipulations on a wide variety of scales from single ion channel proteins to whole organs like the heart. In neuroscience, it includes measurements of the electrical activity of neurons, and, in particular, action potential activity. Recordings of large-scale electric signals from the nervous system, such as electroencephalography, may also be referred to as electrophysiological recordings. They are useful for electrodiagnosis and monitoring.
Antennae, sometimes referred to as "feelers", are paired appendages used for sensing in arthropods.
The vomeronasal organ (VNO), or Jacobson's organ, is the paired auxiliary olfactory (smell) sense organ located in the soft tissue of the nasal septum, in the nasal cavity just above the roof of the mouth in various tetrapods. The name is derived from the fact that it lies adjacent to the unpaired vomer bone in the nasal septum. It is present and functional in all snakes and lizards, and in many mammals, including cats, dogs, cattle, pigs, and some primates. Some humans may have physical remnants of a VNO, but it is vestigial and non-functional.
A chemoreceptor, also known as chemosensor, is a specialized sensory receptor which transduces a chemical substance to generate a biological signal. This signal may be in the form of an action potential, if the chemoreceptor is a neuron, or in the form of a neurotransmitter that can activate a nerve fiber if the chemoreceptor is a specialized cell, such as taste receptors, or an internal peripheral chemoreceptor, such as the carotid bodies. In physiology, a chemoreceptor detects changes in the normal environment, such as an increase in blood levels of carbon dioxide (hypercapnia) or a decrease in blood levels of oxygen (hypoxia), and transmits that information to the central nervous system which engages body responses to restore homeostasis.
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.
The patch clamp technique is a laboratory technique in electrophysiology used to study ionic currents in individual isolated living cells, tissue sections, or patches of cell membrane. The technique is especially useful in the study of excitable cells such as neurons, cardiomyocytes, muscle fibers, and pancreatic beta cells, and can also be applied to the study of bacterial ion channels in specially prepared giant spheroplasts.
An olfactory receptor neuron (ORN), also called an olfactory sensory neuron (OSN), is a sensory neuron within the olfactory system.
Olfactory receptors (ORs), also known as odorant receptors, are chemoreceptors expressed in the cell membranes of olfactory receptor neurons and are responsible for the detection of odorants which give rise to the sense of smell. Activated olfactory receptors trigger nerve impulses which transmit information about odor to the brain. These receptors are members of the class A rhodopsin-like family of G protein-coupled receptors (GPCRs). The olfactory receptors form a multigene family consisting of around 800 genes in humans and 1400 genes in mice.
The rhinarium is the furless skin surface surrounding the external openings of the nostrils in many mammals. Commonly it is referred to as the tip of the snout, and breeders of cats and dogs sometimes use the term nose leather. Informally, it may be called a "truffle", "wet snout" or "wet nose," because its surface is moist in some species: for example, healthy dogs and cats.
The antennal lobe is the primary olfactory brain area in insects. The antennal lobe is a sphere-shaped deutocerebral neuropil in the brain that receives input from the olfactory sensory neurons in the antennae and mouthparts. Functionally, it shares some similarities with the olfactory bulb in vertebrates. The anatomy and physiology function of the insect brain can be studied by dissecting open the insect brain and imaging or carrying out in vivo electrophysiological recordings from it.
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.
Electroantennography or EAG is a technique for measuring the average output of an insect antenna to its brain for a given odor. It is commonly used in electrophysiology while studying the function of the olfactory pathway in insects. The technique was invented in 1957 by German biologist Dietrich Schneider and shares similarities with electro-olfactography.
Odorant-binding proteins (OBPs) are small soluble proteins secreted by auxiliary cells surrounding olfactory receptor neurons, including the nasal mucus of many vertebrate species and in the sensillar lymph of chemosensory sensilla of insects. OBPs are characterized by a specific protein domain that comprises six α-helices joined by three disulfide bonds. Although the function of the OBPs as a whole is not well established, it is believed that they act as odorant transporters, delivering the odorant molecules to olfactory receptors in the cell membrane of sensory neurons.
A sensillum is an arthropod sensory organ protruding from the cuticle of exoskeleton, or sometimes lying within or beneath it. Sensilla appear as small hairs or pegs over an individual's body. Inside each sensillum there are two to four sensory neurons. These neurons, or receptors, gather information about environment the arthropod is in:
The genetics of social behavior is an area of research that attempts to address the question of the role that genes play in modulating the neural circuits in the brain which influence social behavior. Model genetic species, such as D.melanogaster and Apis mellifera, have been rigorously studied and proven to be instrumental in developing the science of genetics. Many examples of genetic factors of social behavior have been derived from a bottom-up method of altering a gene and observing the change it produces in an organism. Sociogenomics is an integrated field that accounts for the complete cellular genetic complement of an organism from a top-down approach, accounting for all biotic influences that effect behavior on a cellular level.
The sense of smell, or olfaction, is the special sense through which smells are perceived. The sense of smell has many functions, including detecting desirable foods, hazards, and pheromones, and plays a role in taste.
An organism is said to be sexually dimorphic when male and female conspecifics have anatomical differences in features such as body size, coloration, or ornamentation, but disregarding differences of reproductive organs. Sexual dimorphism is usually a product of sexual selection, with female choice leading to elaborate male ornamentation and male-male competition leading to the development of competitive weaponry. However, evolutionary selection also acts on the sensory systems that receivers use to perceive external stimuli. If the benefits of perception to one sex or the other are different, sex differences in sensory systems can arise. For example, female production of signals used to attract mates can put selective pressure on males to improve their ability to detect those signals. As a result, only males of this species will evolve specialized mechanisms to aid in detection of the female signal. This article uses examples of sex differences in the olfactory, visual, and auditory systems of various organisms to show how sex differences in sensory systems arise when it benefits one sex and not the other to have enhanced perception of certain external stimuli. In each case, the form of the sex difference reflects the function it serves in terms of enhanced reproductive success.
Calyptra thalictri is a moth of the family Erebidae. It is native to the area ranging from Japan and Korea to China and Malaysia, west through the Urals to Southern Europe, but it has recently expanded its range to northern Europe. In 2000, it was observed in Finland and in 2008 it was recorded even further west, in Sweden.
Phenacoccus manihoti is a mealybug insect species.
Insect olfaction refers to the function of chemical receptors that enable insects to detect and identify volatile compounds for foraging, predator avoidance, finding mating partners and locating oviposition habitats. Thus, it is the most important sensation for insects. Most important insect behaviors must be timed perfectly which is dependent on what they smell and when they smell it. For example, olfaction is essential for locating host plants and hunting prey in many species of insects, such as the moth Deilephila elpenor and the wasp Polybia sericea, respectively.