antennal lobe
{{Short description|Brain area in insects}}
The antennal lobe is the primary (first order) 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.{{cite journal |last1=Scott |first1=Kristin |last2=Brady |first2=Roscoe |last3=Cravchik |first3=Anibal |last4=Morozov |first4=Pavel |last5=Rzhetsky |first5=Andrey |last6=Zuker |first6=Charles |last7=Axel |first7=Richard |title=A Chemosensory Gene Family Encoding Candidate Gustatory and Olfactory Receptors in Drosophila |journal=Cell |date=March 2001 |volume=104 |issue=5 |pages=661–673 |doi=10.1016/S0092-8674(01)00263-X |pmid=11257221 |s2cid=13677779 |doi-access=free }} The anatomy and physiology function of the insect brain can be studied by dissecting open the insect brain and imaging or carrying out [https://www.youtube.com/playlist?list=PL7949yMfsdqgqEGqHwKeiBWR8aPUkEtuk in vivo electrophysiological recordings] from it.
Structure
In insects, the olfactory pathway starts at the antennae (though in some insects like Drosophila there are olfactory sensory neurons in other parts of the body) from where the sensory neurons carry the information about the odorant molecules impinging on the antenna to the antennal lobe. The antennal lobe is composed of densely packed neuropils, termed glomeruli, where the sensory neurons synapse with the two other kinds of neurons, the postsynaptic principal neurons (termed projection neurons) and local interneurons. Each olfactory sensory neuron expresses a single odorant receptor type and targets the same glomeruli as other olfactory sensory neurons expressing that receptor type, such that each glomerulus houses all or the majority of sensory neurons of a given receptor type.{{Cite journal|author1=Leslie B. Vosshall|author2=Allan M. Wong|author3=Richard Axel|name-list-style=amp|year=2000 |title=An olfactory sensory map in the fly brain |journal=Cell |volume=102 |issue=2 |pages=147–159 |pmid=10943836 |doi=10.1016/S0092-8674(00)00021-0 |s2cid=17573876 |doi-access=free }}{{Cite journal |author1=Gregory S. X. E. Jefferis|author2=Elizabeth C. Marin|author3=Reinhard F. Stocker|author4=Liqun Luo |year=2001 |title=Target neuron prespecification in the olfactory map of Drosophila |journal=Nature |volume=414 |issue=6860 |pages=204–208 |pmid=11719930 |doi=10.1038/35102574 |url=http://www.stanford.edu/group/luolab/Pdfs/Jefferis_et_al_Nature_2001.pdf |bibcode=2001Natur.414..204J |s2cid=4431800 }} The number and identities of glomeruli are species specific; most species contain 40 to 160 individually identifiable glomeruli within the antennal lobe. For instance, there are 32 glomeruli in mosquito,{{cite journal |author1=B. S. Hansson|author2=S. Anton|name-list-style=amp|year=2000 |title=Function and morphology of the antennal lobe: new developments |journal=Annual Review of Entomology |volume=45 |pages=203–231 |pmid=10761576 |doi=10.1146/annurev.ento.45.1.203 |s2cid=11846340 |url=https://lup.lub.lu.se/record/149477 }} 43 glomeruli in the fruit fly antennal lobe, and 203 glomeruli in cockroach.{{cite journal |last1=Watanabe |first1=Hidehiro |last2=Nishino |first2=Hiroshi |last3=Mizunami |first3=Makoto |last4=Yokohari |first4=Fumio |title=Two Parallel Olfactory Pathways for Processing General Odors in a Cockroach |journal=Frontiers in Neural Circuits |date=5 May 2017 |volume=11 |pages=32 |doi=10.3389/fncir.2017.00032 |pmid=28529476 |pmc=5418552 |doi-access=free }} The local neurons, which are primarily inhibitory, have their neurites restricted to the antennal lobe. Projection neurons, which generally receive information from a single glomerulus, project to higher brain centers such as the mushroom body and the lateral horn.{{cite journal |author1=Mark Stopfer|author2=Vivek Jayaraman|author3=Gilles Laurent|name-list-style=amp|year=2003 |title=Intensity versus identity coding in an olfactory system |journal=Neuron |volume=39 |issue=6 |pages=991–1004 |pmid=12971898 |doi=10.1016/j.neuron.2003.08.011 |s2cid=12813651 |doi-access=free }}{{cite journal |last1=Gronenberg |first1=W. |last2=López-Riquelme |first2=G.O. |title= Multisensory convergence in the mushroom bodies of ants and bees |journal= Acta Biologica Hungarica |volume=55 |issue=1–4 |date=February 2014 |pages=31–37 |doi= 10.1556/ABiol.55.2004.1-4.5 |pmid=15270216 |url=https://real.mtak.hu/69881/1/abiol.55.2004.1-4.5.pdf }}{{cite journal |last1=López-Riquelme |first1=G.O. |title= Odotopic afferent representation of the glomerular antennal lobe organization in the mushroom bodies of ants (Hymenoptera: Formicidae): Comparisons between two species |journal= TIP Revista Especializada en Ciencias Químico-Biológicas |volume=17 |issue=1 |date=June 2014 |pages=15–31|doi= 10.1016/S1405-888X(14)70317-1 |doi-access=free }} The interaction between the olfactory receptor neurons, local neurons and projection neurons reformats the information input from the sensory neurons into a spatio-temporal code before it is sent to higher brain centers.{{Cite journal |author=Gilles Laurent |year=2002 |title=Olfactory network dynamics and the coding of multidimensional signals |journal=Nature Reviews Neuroscience |volume=3 |issue=11 |pages=884–895 |pmid=12415296 |doi=10.1038/nrn964 |s2cid=17379080 }}{{Cite journal|author1=Mark Stopfer|author2=Gilles Laurent|name-list-style=amp|year=1999 |title=Short-term memory in olfactory network dynamics |journal=Nature |volume=402 |issue=6762 |pages=664–668 |pmid=10604472 |doi=10.1038/45244 |bibcode=1999Natur.402..664S |s2cid=4366918 |url=https://resolver.caltech.edu/CaltechAUTHORS:20150616-084753006 }}
References
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Further reading
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- {{Cite journal |author1=Linda Buck|author2=Richard Axel|name-list-style=amp|year=1991 |title=A novel multigene family may encode odorant receptors: a molecular basis for odor recognition |journal=Cell |volume=65 |issue=1 |pages=175–183 |pmid=1840504 |doi=10.1016/0092-8674(91)90418-X|s2cid=6548928 |doi-access=free }}
- {{Cite journal |author1=Andreas Keller|author2=Leslie B. Vosshall|name-list-style=amp|year=2004 |title=A psychophysical test of the vibration theory of olfaction |journal=Nature Neuroscience |volume=7 |issue=4 |pages=337–338 |pmid=15034588 |doi=10.1038/nn1215|s2cid=1073550 }}
- {{cite journal |author=Luca Turin |year=1996 |title=A spectroscopic mechanism for primary olfactory reception |journal=Chemical Senses |volume=21 |issue=6 |pages=773–791 |pmid=8985605 |doi=10.1093/chemse/21.6.773|doi-access=free }}
- {{cite thesis |type=Ph.D. |last=López-Riquelme |first=Germán Octavio |date=2008 |title= Hormigas como sistemas modelo para el comportamiento complejo. Bases neurobiológicas de la comunicación química y la división del trabajo en las hormigas |url=https://www.researchgate.net/publication/200819205 |doi=10.13140/RG.2.1.3145.1689 |publisher=Universidad Nacional Autónoma de México}}
- {{Cite journal |author=Luca Turin |year=2002 |title=A method for the calculation of odor character from molecular structure |journal=Journal of Theoretical Biology |volume=216 |issue=3 |pages=367–385 |pmid=12183125 |doi=10.1006/jtbi.2001.2504|bibcode=2002JThBi.216..367T }}
- {{cite book |author=Chandler Burr |year=2003 |title=The Emperor of Scent: A Story of Perfume, Obsession, and the Last Mystery of the Senses |isbn=0-375-50797-3 |publisher=Random House |url-access=registration |url=https://archive.org/details/emperorofscentst00burr }}
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=Reviews of antennal lobe anatomy=
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- {{cite journal |author1=U. Homberg|author2=T. A. Christensen|author3=J. G. Hildebrand|name-list-style=amp|year=1989 |title=Structure and function of the deutocerebrum in insects |journal=Annual Review of Entomology |volume=34 |pages=477–501 |pmid=2648971 |doi=10.1146/annurev.en.34.010189.002401}}
- {{cite journal |author1=C. Giovanni Galizia|author2=Wolfgang Rössler|name-list-style=amp|year=2010 |title=Parallel olfactory systems in insects: anatomy and function |journal=Annual Review of Entomology |volume=55 |pages=399–420 |pmid=19737085 |doi=10.1146/annurev-ento-112408-085442|url=http://nbn-resolving.de/urn:nbn:de:bsz:352-opus-121644 }}
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