Trigeminal interaction, olfactory

Devitsina G.V. and Cherova L. (1992). The trigeminal nerve system and its interaction with olfactory and taste system in fishes. In Chemical Signals in Vertebrates 6 (Doty R.L. and Miiller-Schwarze D., eds.). Plenum, New York, pp. 85-88. 

Bouvet, J. F., Godinot, F., Delaleu, J. C., and Holley, A. (1989). Interaction between the olfactory and the trigeminal systems in the frog. Chemical Senses 14,200. 

Many airborne substances are complex stimuli. They are combinations of many chemicals which can interact at one or several levels before or during the perception chemical or physical interaction in the gas mixture, interaction of molecules at the receptor surfaces (olfactory and trigeminal systems), peripheral interaction in the nervous system and finally interaction in the central nervous system. Therefore, effects such as masking, neutralisation and counteraction are not surprising in gas mixtures [13]. 

About 60% of odorants also trigger receptors in the trigeminal nerve fibres, which run around the entire surface of the nasal cavity. The interaction between the olfactory and trigeminal senses will be discussed later under the section Signal Processing . 

Odour only exists in the higher brain and is a synthesis of signals from the olfactory pathway, those of the trigeminal system, those from other senses (e.g. taste) and so on. There are many gates along the pathway with the potential to shut off or enhance odour signals. All of the various nerve pathways (those due to different smells and those from other channels interact with each other and so we can have odour enhancement or suppression as a result of these various interactions. For instance, any... 

Analogous events occur in the nose when many odorants interact with the epithelia therein. The odor component is conveyed via the odorant s interaction with molecular receptors on olfactory sensory neurons (first cranial nerve) in the olfactory epithelium [9] irritation is initiated by interactions with receptors or other mechanisms that stimulate the trigeminal (fifth cranial) nerve [10]. The term chemesthesis has been applied to distinguish this sensory experience from olfaction or, in the oral cavity, taste [11,12]. Importantly, chemesthesis is a bodywide experience. It is only on some portions of the head, e.g., eyes, nose, mouth, and some other facial areas, where information is conveyed by the trigeminal nerve (Fig. 1). 

For a terrestrial animal, flavor may be defined as the composite sensation resulting from placing something in the mouth. Therefore, flavor may Include taste, olfactory, vomeronasal, trigeminal and other chemical sense Inputs as well as tactile, temperature and proprioceptive cues. Thus, the subjective sensation we call flavor is the result of interactions of a complex of receptors. The bulk of experimental work in this field has focussed upon one class of receptors and associated CNS processes, the taste system. There are powerful arguments that the taste system is a uniquely important component in regulating flavor perception and food Intake (e.g.,, but other sensory components significantly influence flavor perception (e.g., ). 

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