Olfactory pathway

Perl, D.P. and Good, P.F. (1987). Uptake of aluminium into central nervous system along nasal-olfactory pathways. Lancet i, 1028. 

An extra-bulbar olfactory pathway (EBOP) is present in teleosts and in some non-teleost genera. Olfactory fibres run within the medial forebrain bundle, and can be traced (by SBA lectin binding) beyond the olfactory bulb into areas such as the ventral telencephalon, and/or the preoptic nucleus (Hofmann and Meyer, 1995). The projection of the EBOP fibres is similar in the sturgeon, but in other non-teleosts the primary olfactory fibres reach diencephalic target nuclei. 

Chuah M. and Zheng D. (1992). The human primary olfactory pathway fine structural and cytochemical aspects during development, and in adults. Micros Res Tech 23, 76-85. 

Hofmann M. and Meyer D. (1995). The extrabulbar olfactory pathway — primary olfactory fibres by passing the olfactory bulb in bony fishes. Brain Behav Evol 46, 378-388. 

Kauer J.S. (1991). Contributions of topography and parallel processing to odor coding in the vertebrate olfactory pathway. Trends Neurosci 14, 79-85. 

Lehman M.N. and Winans S.S. (1982). Vomeronasal and olfactory pathways to the amygdala controlling male hamster sexual behavior — autoradiographic and behavioral analyses. Brain Res 240, 27-41. 

Licht G. and Meredith M. (1987). Convergence of main and accessory olfactory pathways onto single neurons in the hamster amygdala. Exp Brain Res 69, 7-18. 

Saito S. and Taniguchi K. (2000). Expression patterns of glyco-conjugates in the three distinctive olfactory pathways of the clawed frog, Xenopus laevis. J Vet Med Sci 62, 153-159. 

Saltiere-Imerly R.B., Young B.J. and Capozza M.A. (1989). Estrogen differentially regulates neuropeptide gene expression in a sexually dimorphic olfactory pathway. Proc Natl Acad Sci 86, 4766-4770. 

Simerly R. (1990). Hormonal control of neuropeptide gene expression in sexually dimorphic olfactory pathways. Trends Neurosci 13, 104-110. 

Comparative and phylogenetic considerations such as those outlined in the preceding paragraphs readily lead to speculation that the olfactory systems of modern animals share common antecedents and therefore probably also share common principles of functional organization and information processing. We might ask, What attributes of chemical stimuli do olfactory systems analyze and encode How are those features mapped in "neural space" at various levels of the olfactory pathway How are cells of the pathway organized, and what mechanisms do they use, to accomplish this analysis of odors in the environment ... 

Different odor substances stimulate different patterns of ORCs in the olfactory epithelium, owing to the different sensitivity spectra of the ORCs (28). The pattern of activity in the epithelium evoked by a particular odor substance constitutes the first molecular image of that stimulus, which represents the determinants of the stimulating molecules (13). Thus, although olfaction is not a spatial sensory modality, in contrast, for example, to vision and somatosensation, the initial representation of an odor stimulus in the olfactory pathway does have spatial structure. 

An important insight from many studies (28) is that the response patterns—the molecular images—at various levels in the central olfactory pathway are set up by the differential responses of the ORCs in the peripheral receptor epithelium. These studies also suggest that functional modules, which may correspond to recognizable structural units such as individual glomeruli with their associated cells, in the olfactory bulb or lobe participate in the analysis of olfactory information conveyed to them... 

Our neurophysiological studies have focused on three important properties of the sex-pheromonal signal its quality (chemical composition of the blend), quantity (concentrations of components), and intermit-tency [owing to the fact that the pheromone in the plume downwind from the source exists in filaments and blobs of odor-bearing air interspersed with clean air (47, 48)]. Each of these properties of the pheromonal message is important, as the male moth gives his characteristic behavioral responses only when the necessary and sufficient pheromone components A and B are present in the blend (44), when the concentrations and blend proportions of the components fall within acceptable ranges (49), and when the pheromone blend stimulates his antennae intermittently (39, 50). In our studies, we examine how each of these important aspects of the odor stimulus affects the activity of neurons at various levels in the olfactory pathway. 

Coronas V, Krantic S, Jourdan F, Moyse E. 1999. Dopamine receptor coupling to adenylyl cyclase in rat olfactory pathway a combined pharmacological-radioautographic approach. Neuroscience 90 69-78. 

The uptake of manganese by plants and its transport within plants has been reviewed. " Reviews describing Mn speciation in the blood and the transport kinetics of Mn into the central nervous system of mammals have appeared. Manganese has a unique capacity to be taken up via the olfactory pathways and pass trans-neuronally to other parts of the brain. ... 

Schneiderman, A. M. and Hildebrand, J. G. (1985). Sexually dimorphic development of the insect olfactory pathway. Trends in Neurosciences 8 494 199. 

Some olfactory neurons may use a second transduction mechanism. They have receptors coupled through G proteins to PLC rather than to adenylyl cyclase. Signal reception in these cells triggers production of IP3 (Fig. 12-19), which opens IP3-gated Ca2+ channels in the ciliary membrane. Influx of Ca2+ then depolarizes the ciliary membrane and generates a receptor potential or regulates Ca2+-dependent enzymes in the olfactory pathway. 

Topical application of MnCl2 has also been investigated [36]. Application of MnCl2 to the naris of mice allowed for visualization of the olfactory pathway as the Mn2+ ions were transported up the neuronal tract. Administration of this agent did not affect the ability of the mice to detect odors and the amount of manganese(II) accumulated in tissue was below the intracellular toxicity levels. Injection of MnCl2 into the aqueous humor of the eyes of mice demonstrated enhancement of the vitreal humor and the optic tract. 

The number of neurons may decrease in some areas, such as substantia nigra (in Parkinson s disease), nucleus basalis of Meynert, the hippocampus, the adjacent temporal cortex, and olfactory pathways (in Alzheimer s disease). 

Considerable evidence concerning the central olfactory pathways of insects is available and may be used to draw a reasonable hypothesis as to the organization and physiology (Hansson and Anton, 2000). In these model dipteran and lepidopteran systems, electrical activity in the form of action potentials that arise in response to the signal transduction events initiated by the olfactory stimulus is directed along ORN axons to the AL where synaptic connections are made that mediate signaling to higher centers within the insect CNS (Hildebrand and... 

Anton S. (1996) Central olfactory pathways in mosquitoes and other insects. Ciba Found. Symp. 200, 184-192 discussion 192-196, 226-232. 

Kent K. S., Harrow I. D., Quartararo P. and Hildebrand J. G. (1986) An accessory olfactory pathway in Lepidoptera the labial pit organ and its central projections in Manduca sexta and certain other sphinx moths and silk moths. Cell Tissue Res. 245, 237-245. 

J. (2002) Visual arrestins in olfactory pathways of Drosophila and the malaria vector mosquito Anophelesgambiae. Proc. Natl. Acad. Sci. USA 99, 1633-1638. 

Shepherd G. (1985) Are there labeled lines in the olfactory pathway In Taste, Olfaction and the Central Nervous System, ed. D. Pfaff, pp. 307-321. Rockefeller Press, New York. 

Vogt R. G. and Lemer M. R. (1989) Two groups of odorant binding proteins in insects suggest specific and general olfactory pathways. Neurosci. Abstr. 15, 1290. 

Merrill C. E., Riesgo-Escovar J. R., Pitts R. J., Kafatos F. C., Carlson J. R. and Zwiebel L. J. (2002) Visual arrestins in olfactory pathways of Drosophila and the malaria vector mosquito Anopheles gambiae. Proc. Natl. Acad. Sci. USA 99, 1633-1638. Moore P. A. (1994) A model of the role of adaptation and disadaptation in olfactory receptor neurons implications for the coding of temporal and intensity patterns in odor signals. Chem. Senses 19, 71-86. 

Dual olfactory pathway in the honeybee, Apis mellifera. J. Comp. Neurol., 499, 933-952. 

Figure 5.9 The human olfactory system. (A) Section through the nose. (B) Section through the cribriform plate. (C) The olfactory pathway to the cerebrum (forebrain). This shows the pathway of olfactory sensation. Nasal stimulation begins at the cilia of the olfactory receptor cells located at the ends of the olfactory nerves. The olfactory nerves then carry the impulse to the cerebrum, resulting in the sense of smell.

Nasal cavity —> olfactory mucosa also nasal cavity —> systemic circulation Direct from nose to brain Direct from nose to brain Direct from nose to brain Direct from nose to brain Nasal cavity —> CSF Nasal cavity —> CSF Direct from nose to brain via olfactory pathway... 

---