title: The olfactory system as a puzzle: playing with its pieces.
abstract: The mammalian olfactory bulb (OB) has all the features of a whole mammalian brain but in a more reduced space: neuronal lamination, sensory inputs, afferences, or efferences to other centers of the central nervous system, or a contribution of new neural elements. Therefore, it is widely considered as "a brain inside the brain." Although this rostral region has the same origin and general layering as the other cerebral cortices, some distinctive features make it very profitable in experimentation in neurobiology: the sensory inputs are driven directly on its surface, the main output can be accessed anatomically, and new elements appear in it throughout adult life. These three morphological characteristics have been manipulated to analyze further the response of the whole OB. The present review offers a general outlook into the consequences of such experimentation in the anatomy, connectivity and neurochemistry of the OB after (a) sensory deprivation, mainly by naris occlusion; (b) olfactory deinnervation by means of olfactory epithelium damage, olfactory nerve interruption, or even olfactory tract disruption; (c) the removal of the principal neurons of the OB; and (d) management of the arrival of newborn interneurons from the rostral migratory stream. These experiments were performed using surgical or chemical methods, but also by means of the analysis of genetic models, some of whose olfactory components are missing, colorless or mismatching within the wild-type scenario of odor processing.
authors.affiliation: Laboratory of Neuronal Plasticity and Neurorepair, Institute for Neuroscience of Castile and Leon, Universidad de Salamanca, Salamanca, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Díaz
authors.forename: C
authors.initials: C
authors.lastname: Gómez
authors.forename: R
authors.initials: R
authors.lastname: Muñoz-Castañeda
authors.forename: F
authors.initials: F
authors.lastname: Baltanás
authors.forename: J R
authors.initials: JR
authors.lastname: Alonso
authors.forename: E
authors.initials: E
authors.lastname: Weruaga
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D006801:Humans; D007395:Interneurons / Q000378:metabolism / Q000473:pathology; D009415:Nerve Net / Q000378:metabolism / Q000473:pathology; D055495:Neurogenesis; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D009812:Odorants; D000857:Olfaction Disorders / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology* / Q000523:psychology; D009830:Olfactory Bulb / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D055696:Olfactory Perception / Q000235:genetics; D012683:Sensory Deprivation; D015398:Signal Transduction; D012903:Smell / Q000235:genetics
keywords: nervous system; neuronal lamination; olfaction; olfactory bulb