Single sensillum recording (SSR) is a form of extracellular electrophysiology. This technique measures

action potential An action potential (also known as a nerve impulse or "spike" when in a neuron) is a series of quick changes in voltage across a cell membrane. An action potential occurs when the membrane potential of a specific Cell (biology), cell rapidly ri ...

s, generated from olfactory sensory neurons (OSNs), through a single

sensilla A sensillum (plural ''sensilla'') 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 ...

on an insects' antennae. These sensillum are hair-like structures that protrude through the

cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...

as well as several other auxiliary and sensory cells. 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 Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for Separation process, separating and analyzing compounds that can be vaporized without Chemical decomposition, decomposition. Typical uses of GC include t ...

, sensillum incision, diffusion, or

microinjection Microinjection is the use of a glass micropipette to inject a liquid substance at a microscopic or borderline macroscopic level. The target is often a living cell but may also include intercellular space. Microinjection is a simple mechanical pro ...

. Some applications for this technique include testing

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

sensitivity, testing reactions to volatile compounds in the environment, and reactivity to chemical cues from other organisms.

Methods

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. In order to record, a location as close to the sensilla (usually the eye) is penetrated with a

ground Ground may refer to: Geology * Land, the solid terrestrial surface of the Earth * Soil, a mixture of clay, sand and organic matter present on the surface of the Earth Electricity * Ground (electricity), the reference point in an electrical circ ...

electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or a gas). In electrochemical cells, electrodes are essential parts that can consist of a varie ...

. 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. Alternatively, one may test using different sensilla.

References

{{reflist Electrophysiology

Methods

See also

References