Olfactory cortex

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The olfactory cortex is part of the olfactory brain ( rhinencephalon ) and contains those structures of the endbrain that serve as secondary olfactory areas for the perception and central processing of smells . They lie in the basal cortical areas of the cerebral hemispheres and receive direct projections from the primary olfactory area in the olfactory bulb ( bulb olfactory ) on each side.

The neurites of olfactory cells of the olfactory epithelium of the nasal mucosa, the fibers of the olfactory nerve on the same side , terminate in the onion-shaped bulb , an advanced part of the endbrain . They enter as fila olfactoria through the skull bone and into the overlying globe. In tangled forms ( glomeruli olfactorii ) they form synapses with the mitral cells of the olfactory bulb. These are 2. afferent neurons of the olfactory tract ; their axons run centripetally in the olfactory tract and project into the secondary olfactory areas.

While the globe and olfactory tract are slender structures in humans that lie against the base of the frontal lobe , the olfactory bulb in non-primates is much more pronounced in relation to the rest of the endbrain and protrudes forward from it.

The olfactory cortex in the narrower sense is an allocortex and a very old genealogical structure; it is therefore also referred to as the paleocortex . In addition to the olfactory tubercle (the substantia perforata anterior ), this includes an adjacent area known as the cortex (prae) piriformis . This is built up in three layers, like the medially adjoining cortical part ( nucleus corticalis ) of the amygdala , which also belongs to the olfactory cortex. However, only a small rostral section of the so-called area entorhinalis in the parahippocampal gyrus is included.

From these secondary areas there are tertiary projections to the area septalis, the area insularis anterior, the basolateral tonsil nucleus, the hippocampus formation as well as the area praeoptica and the hypothalamus . Portions of the prepiriform cortex also project to the dorsomedial thalamus in the diencephalon , which in turn is connected to neocortical regions in the orbital frontal lobe (conscious olfactory perception).

Connections between the structures of the olfactory cortex on both sides exist via the rostral commissure . Groups of neurons from the non-laminated nucleus olfactorius anterior , which is located in the trigonum olfactorium and connected to the tractus olfactorius , also connect to the opposite side . They serve in particular as a switching point for (declining) mutual connections between the two bulbi olactorii.

See also

literature

  • Alfred Benninghoff (welcomed), Detlev Drenckhahn u. a. (Ed.): Anatomy. Macroscopic anatomy, histology, embryology, cell biology . Urban & Schwarzenberg, Munich 1994,
    • Vol. 2 kidneys, reproductive organs, endocrine glands, nervous system, sensory organs, skin . 15th revised 1994 edition, ISBN 3-541-00255-7 .
  • Otto Detlev Creutzfeldt : Cortex cerebri. Performance, structural and functional organization . OUP, Oxford 1995, ISBN 0-19-852324-6 .
  • Karl Zilles, Gerd Rehkämper: Functional Neuroanatomy. Textbook and atlas . Springer, Berlin 1993, ISBN 3-540-54690-1 .

Individual evidence

  1. Olfactory cortex in the Lexicon of Neuroscience on Spektrum.de, accessed on July 23, 2019.