{{no footnotes, date=November 2014
The Stomatogastric Nervous System (STNS) is a commonly studied
neural network
A neural network is a network or neural circuit, circuit of biological neurons, or, in a modern sense, an artificial neural network, composed of artificial neurons or nodes. Thus, a neural network is either a biological neural network, made up ...
composed of several
ganglia
A ganglion is a group of neuron cell bodies in the peripheral nervous system. In the somatic nervous system this includes dorsal root ganglia and trigeminal ganglia among a few others. In the autonomic nervous system there are both sympath ...
in
arthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...
s that controls the motion of the gut and foregut. The network of neurons acts as a
central pattern generator
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 stereo ...
. It is a model system for
motor pattern generation
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 stereo ...
because of the small number of cells, which are comparatively large and can be reliably identified. The system is composed of the
stomatogastric ganglion
The stomatogastric ganglion (STG) is a much studied ganglion (collection of neurons) found in arthropods and studied extensively in decapod crustaceans. It is part of the stomatogastric nervous system.
See also
* Central pattern generator
Cen ...
(STG),
oesophageal ganglion
The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...
and the paired commissural ganglia.
Because of the many similarities between vertebrate and invertebrate systems, especially with regards to basic principles of neuronal function, invertebrate model systems such as the
crustacea
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...
n ''stomatogastric nervous system'' continue to provide key insight into how neural circuits operate in the numerically larger and less accessible vertebrate CNS.
Understanding how neuronal networks enable animals and humans to make coordinated movements is a continuing goal of neuroscience research. The stomatogastric nervous system of decapod crustaceans, which controls aspects of feeding, has contributed significantly to the general principles guiding our present understanding of how rhythmic motor circuits operate at the cellular level.
Rhythmic behaviors include all motor acts that at their core involve a rhythmic repeating set of movements. The circuits underlying such rhythmic behaviors,
central pattern generator
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 stereo ...
s (CPGs), all operate on the same general principles. These networks remain rhythmic in the completely isolated nervous system, even in the absence of all rhythmic neuronal input, including feedback from
sensory system
The sensory nervous system is a part of the nervous system responsible for processing sensory information. A sensory system consists of sensory neurons (including the sensory receptor cells), neural pathways, and parts of the brain involved ...
s. Although the details differ in each circuit, all CPGs use the same set of cellular-level mechanisms for circuit construction. More importantly, CPG circuits are usually not dedicated to producing a single neuronal activity pattern. This flexibility results largely from the ability of different
neuromodulator
Neuromodulation is the physiological process by which a given neuron uses one or more chemicals to regulate diverse populations of neurons. Neuromodulators typically bind to metabotropic, G-protein coupled receptors (GPCRs) to initiate a second ...
s to change the cellular and synaptic properties of individual circuit neurons. When the properties of circuit components are changed, the output of the circuit itself is modified. These aspects of CPG operation are often shared by other circuits, enabling a general understanding of neuronal circuit operation.
The STNS contains a set of distinct but interacting motor circuits. The understanding of this multifunctional network contributed importantly to the general understanding of neural circuit operation. The value of this system has resulted from its accessibility, the use of several innovative techniques, and the combined research effort of around 15 laboratories over the past ~30 years.