Olfactory organ is an important sensory system and therefore it can serve as the research object of the neural information processing and biologic evolution due to its simplicity and ancient characteristics of the system. Besides, the olfactory biosensors based on olfactory receptor neurons (ORNs) have prosperous applications in environmental monitoring and food testing. This review introduces configuration and signal transduction of ORNs. Then it examines neuronal coding strategies and how the characteristic of responses to mechanical stimuli applied to olfactory processing. Finally, it illustrates the recent research of olfactory biosensors based on ORNs/olfactory receptors and puts forward the direction of future research.
Biosensing Techniques ; Humans ; Olfactory Perception ; physiology ; Olfactory Receptor Neurons ; physiology ; Signal Transduction ; Smell ; physiology

OBJECTIVETo explore the feasibility of functional magnetic resonance imaging (fMRI) in analysis of olfaction function with modified OEP-98C olfactometer and event-related design.

METHODSSix young right-handed men underwent olfactory fMRI with event-related design. OEP-98C olfactometer was modified to accommodate MR environment. There were 2 types of tasks in the experiment. In one task, only isoamyl acetate was used as odorant. In the other task, to avoid possible decreased olfactory attention, vanillin was given before each presentation of isoamyl acetate.

RESULTSIn both tasks, uniform activation in piriform cortex and secondary olfactory cortexes was determined. The activation of piriform cortex was not significantly different between the two tasks (P > 0.01).

CONCLUSIONSWith isoamyl acetate as odorant, modified OEP-98C olfactometer, and event-related design, olfaction fMRI can depict cortex activation at primary and secondary olfactory cortex. Applying other odorant with similar quality to avoid olfactory attention decrease can not promote depiction of activation in primary olfactory cortex.

Adult ; Evoked Potentials ; physiology ; Feasibility Studies ; Humans ; Magnetic Resonance Imaging ; methods ; Male ; Olfactory Pathways ; physiology ; Olfactory Perception ; physiology ; Pentanols

OBJECTIVES: We report two cases of anosmia that were suspected to be caused by chronic chlorine exposure in cleansing works METHODS: We examined the cases in order to assess the work-relatedness of their anosmia. We conducted olfactory threshold test and olfactory perception test repeatedly at one-month intervals. Using ion chromatography, we analyzed the detergent that the workers had been using for several years before their olfactory function decreased. RESULTS: A 59-year-old male who had worked in a cleansing process for 10 years (1983-1993) and a 58-year-old female who had worked in the same process for 8 years (1987-1995) were diagnosed with anosmia. The cause of the anosmia was presumed to have been the chlorine gas that was generated from the process of heating the detergent-dissolved water, in which chloride was detected. CONCLUSIONS: This is the first report on anosmia due to chronic chlorine exposure. Greater attention needs to be focused on the prevention of anosmia because there are many workers who have been exposed to chlorine gas in chlorine treating and generating processes.
Chlorine* ; Chromatography ; Detergents ; Female ; Heating ; Hot Temperature ; Humans ; Male ; Middle Aged ; Olfaction Disorders* ; Olfactory Perception ; Water

BACKGROUND AND OBJECTIVES: Recently, obesity has become one of the major health problems in our society. To overcome this problem, keeping a balance between food intake and energy expenditure is very important. Many natural substances including essential oils have been suggested for their potential effect on reducing weight. This study was performed to evaluate whether aroma inhalation of essential oil has a role in appetite regulation and works on the central nervous system through the olfactory stimulus. MATERIALS AND METHOD: Food intake was measured after 30 minutes of treatment with essential oil in overnight fasted Sprague-Dawley rats. In the control group, saline was used instead of essential oil. Changes in pro-opiomelanocortin (POMC) and neuropeptide Y (NPY) mRNA expression levels in the hypothalamus were measured following 30 minutes of treatment with geranium essential oil using real-time polymerase chain reaction. RESULTS: Of the seven essential oils, geranium significantly decreased the amount of food intake compared to the control group. Geranium essential oil significantly increased POMC mRNA expression in the hypothalamus, but did not change the NPY mRNA expression. The increased POMC mRNA expression was reversed by treatment with xylocaine, which blocks the olfactory perception. CONCLUSION: These results suggest that geranium essential oil has anorexic effect through the activation of POMC neurons in the hypothalamus via olfactory stimulus.
Appetite Regulation ; Central Nervous System ; Diethylpropion ; Eating ; Energy Metabolism ; Geranium ; Hypothalamus ; Inhalation ; Lidocaine ; Neurons ; Neuropeptide Y ; Obesity ; Oils, Volatile ; Olfactory Perception ; Pro-Opiomelanocortin ; Rats, Sprague-Dawley ; RNA, Messenger

BACKGROUND AND OBJECTIVES: For patients with sudden hearing loss or retina arterial spasm, stellate ganglion block (SGB) has been used as a treatment method to increase the blood flow to the interested area. The aim of this study is to prospectively investigate the efficacy of SGB in patients with olfactory dysfunction following upper respiratory tract infection (URI). MATERIALS AND METHOD: Fifty one patients with anosmia or hyposmia following URI were included. The average duration of olfactory dysfunction was 3.5+/-8.4 years. Thirty eight patients were treated with SGB and compared with the untreated 13 patients. Buthanol threshold test and odor identification test with 16 natural fragrances were used to determine anosmia/hyposmia in these patients and to quantify the improvement of olfactory perception after SGB treatment or follow-up without treatment. RESULTS: Olfactory perception was improved significantly in the treated patients as shown by the buthanol threshold test (p<0.001) and by odor identification test (p<0.001). Subjective olfactory perception was improved in 27 of the 38 treated patients (p<0.001). No complications were observed after SGB and no one reported any worsening in olfactory perception during or after treatment. On the other hand, none of the untreated patients showed any improvement in neither of the tests or the subjective assessment. CONCLUSION: These results suggest that SGB may be a new treatment modality for olfactory dysfunction following URI.
Follow-Up Studies ; Hand ; Hearing Loss, Sudden ; Humans ; Odors ; Olfaction Disorders ; Olfactory Perception ; Prospective Studies ; Respiratory System* ; Respiratory Tract Infections* ; Retina ; Smell ; Spasm ; Stellate Ganglion*