Kenyon cell

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Kenyon Cell is a neuron in the mushroom body of Anthropods.

NJ Strausfeld and LC Hansen, ARLDN, Tucson [1]

Basic information

Named after F. C. Kenyon, who first described them in 1896, Kenyon cells are found within the anthropodal nervous system [1]. Kenyon cells are the intrinsic neurons of the mushroom body [2]. These neurons are involved in the learning and memory pathway of most insects including Drasophila [6]. The shared branching morphology of many thousands of Kenyon cells is what gives the mushroom body its mushroom shape [5]. During development, the Kenyon cells derived from the globuli cells [7].

Neuron Type: Local Interneuron

Anatomy

During the embryonic stage, Kenyon cells production commences. Kenyon cell production ceases late in the postembryonic development, and in some species it continues throughout adulthood [3]. The small, tightly packed cell bodies of the Kenyon cell come together in a region that outlines cup-shaped neuropils called calyces [4]. Also in this calyx area, each Kenyon cell has a dendritic tree. The axons of the Kenyon cells group together at the center of the calyx to from a vertical column of parallel fibers. This vertical column is called the stalk of the mushroom body. In this area, the axons lack side branches and spines, but at the lower end of the stalk, the axons branch once, giving rise to the α and β lobes of the mushroom body [5].

These mushroom bodies are a pair of neuropils, and are composed of a dense network of glia cells and around 2500 Kenyon cells [6]. During mushroom body development, three or more Kenyon cell subpopulations are produced in a specific sequence, and each subpopulation occupies a distinct area within the lobes and calyces. The three Kenyon cell populations are produced at different stages in development. Therefore, the adult mushroom body will be composed of age-based layers of Kenyon cells [3].

Kenyon cells, unlike projection neurons, have been observed to respond very specifically and to fire very rarely. This seems to be advantageous for memory and recall, which is why the mushroom body is believed to be involved in learning [2].

Physiology

In the calyx of the mushroom body, Kenyon cell dendrites receive input from primary sensory (olfactory) neurons originating in the antennal lobe via the inner antennocrebral tract [3]. In the stalk area of the mushroom body, the axons of the Kenyon cells synapse with immediate neighbors. This indicates that the stalk is an important zone of synaptic integration. In the lower branching portion of the stalk, extrinsic neurons intersect. These extrinsic neurons link the mushroom body to other areas of the brain [5]. In learning situations, the anteroglobular tract conducts an olfactory stimulus by secreting dopamine or serotonin into the synaptic cleft at the Kenyon cell dendrite. Also, this afferent input is done by the dorsally paired medial neurons secreting the amnesiac neuropeptide at the synapse [6].

References

1. ^ 1896. The brain of the bee. A preliminary contribution to the morphology of the nervous system of the Arthropoda. J. Comp. Neurol. 6: 133-210

2. Cassenaer, Stijn; Laurent, Gilles.(2007) "Hebbian STDP in mushroom bodies facilitates the synchronous flow of olfactory information in locusts. " Nature 448.7154 : 709-13. Research Library. ProQuest. Georgia State University Library 28 Aug. 2008 <http://www.proquest.com/>

3. Farris, Sarah M. (2005) "Developmental organization of the mushroom bodies of Thermobia domestica (Zygenoma, Lepismatidae): insights into mushroom body evolution from a basal insect." Evolution & Development 7: 150-59.

4. Molina, Yamile, and Sean O'Donnell.(2007) "Mushroom Body Volume Is Related to Social Aggression and Ovary Development in the Paperwasp Polistes Instabilis." Brain, Behavior, and Evolution 70 : 137-44.

5. Ott, Swidbert R., Andrew Philippides, Maurice R. Elphick, and Michael O'Shea. (2007) "Enhanced fidelity of diffusive nitric oxide signalling by the spatial segregation of source and target neurones in the memory centre of an insect brain." European Journal of Neuroscience 25: 181-190.

6. Perumal, Ramasamy; Tan, I.. (2007). "What proteins are involved in learning and memory?" IUBMB Life 59.7 28 Aug. 2008 < http://www.informaworld.com/10.1080/15216540601055331 >

7. ^ Strausfeld NJ (August 2002). "Organization of the honey bee mushroom body: representation of the calyx within the vertical and gamma lobes". J. Comp. Neurol. 450 (1): 4–33. doi:10.1002/cne.10285. PMID 12124764.