Olfactory processing involves a large number of central olfactory structures, interconnected with each other in complex fashion, and incorporating both feed forward and feed back interaction. Thus understanding how these structures in odor acquisition, perception, and memory perform functional roles is a central question in olfactory disorders that can only be addressed using a combination of approaches, including neuroimaging, neurophysiology and behavioral analyses. Recent whole-brain imaging studies have shown that multiple diverse neural structures become activated during tasks involving olfactory stimulation. This article reviews the current understanding of anatomy, sensory physiology of central olfactory structures. Especially the sensory physiology of main olfactory bulb, pyriform cortex, and orbitofrontal cortex will be emphasized here.
Memory ; Neuroimaging ; Neurophysiology ; Odors ; Olfactory Bulb ; Olfactory Pathways* ; Physiology ; Smell

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

This paper introduces the new research achievement and progress of electro-physiology in olfaction and gustation. Classical implements such as patch-clamp or glass pipette are not appropriate in the dynamic detection of cellular signal transportation. In view of this, we have analyzed the feasibilities and challenges of olfactory or gustatory cell-based biosensors such as field effect transistor (FET) and light addressable potentiometric sensor (LAPS). Finally we present the research work carried our in out lab and a future prospective on the development in this field.
Biosensing Techniques ; instrumentation ; methods ; Electrophysiology ; methods ; Humans ; Microchip Analytical Procedures ; methods ; Smell ; physiology ; Taste ; physiology

The characters of modern buildings such as higher airtightness, frequent usage of artificial materials and artificial air conditionings provide suitable conditions for flourishing of microorganisms, especially fungi. Indoor fungi could produce unacceptable musty smells and cause structural damage of building. But the more serious effects are the threatening on human health. They could provoke several allergic diseases, sick building syndrome, organic dust toxic syndrome, and could be the important causative agents of infectious diseases in the immunocompromized host. This paper review the characters, physiology, epidemiology and isolation techniques of the indoor fungi to provide the basic ideas to control the indoor fungi.
Air Conditioning ; Communicable Diseases ; Dust ; Epidemiology ; Fungi* ; Humans ; Physiology ; Sick Building Syndrome ; Smell

OBJECTIVE: To investigate the characteristics of OERPs of young adults. METHOD: Subjects included 55 young volunteers (male/female 25/30) with normosmic. A complete ENT examination, A subjective olfactometry with T&T olfactometer were performed in all subjects. OERPs with stimulus isoamyl acetate (<1,648 x 10(-6)), and air control were obtained in volunteers. RESULT: OERPs were obtained in both male and female volunteers. P2, the primary component of OERPs, was identified in all volunteers. No significant difference was found in latencies of the components of OERPs between male and female volunteers. N1-P2 interpeak amplitudes were larger in the female subjects than male subjects (P<0.05). CONCLUSION P2 component of OERPs is identified in all young adults, both gender and interstimulus interval have impact on N1-P2 interpeak amplitudes.
Adolescent ; Adult ; Evoked Potentials ; Female ; Humans ; Male ; Smell ; physiology ; Young Adult

Olfaction and food intake are interrelated and regulated. In the process of feeding, the metabolic signals in the body and the feeding signals produced by food stimulation are first sensed by the arcuate nucleus of hypothalamus and the nucleus tractus solitarius of brain stem, and then these neurons project to the paraventricular nucleus of hypothalamus. The paraventricular nucleus transmits the signals to other brain regions related to feeding and regulates feeding behavior. In this process, olfactory signals can be transmitted to hypothalamus through olfactory bulb and olfactory cortex to regulate feeding behavior. At the same time, gastrointestinal hormones (ghrelin, insulin, leptin, etc.) and some neurotransmitters (acetylcholine, norepinephrine, serotonin, endocannabinoid, etc.) produced in the process of feeding act on the olfactory system to regulate olfactory function, which in turn affects the feeding itself. This review summaries the research progress of the interaction between olfaction and food intake and its internal mechanism from the aspects of neuronal and hormonal regulation.
Arcuate Nucleus of Hypothalamus/metabolism* ; Feeding Behavior/physiology* ; Hypothalamus ; Paraventricular Hypothalamic Nucleus ; Smell

Objective: To analyze the characteristics of trigeminal event-related potentials (tERPs) in different kinds of olfactory disorders (OD), and to evaluate the importance of tERPs for the patients with olfactory dysfunction. Methods: Clinical data of 314 patients with olfactory dysfunction from the Smell and Taste Clinics in Beijing Anzhen Hospital from 2015 to 2021 were retrospectively reviewed, including 158 males and 156 females, aging from 6 to 78 years. The control group consisted of healthy people from medical examination center, who were gender and age matched. The clinical characteristics of OD were analyzed using Sniffin' Sticks test, olfactory event-related potentials (oERPs), tERPs and acoustic rhinometry test. SPSS 17.0 software was used to compare the difference of tERPs between the two groups, and to analyze the related factors affecting trigeminal function. Results: The ratio of tERPs presence was different in OD caused by different reasons: head traumatic OD (54.9%), post-virus infection OD (63.6%), sinonasal inflammatory OD (68.4%) and OD due to other causes (56.9%). Compared with controls, tERPs signals in OD patients showed a significant lower amplitude in the N₁ wave (all P<0.001), and lower amplitude in the P₂ wave in most OD patients (head trauma t=-4.11, P<0.001; sinonasal inflammation t=-2.04, P=0.046; others t=-2.40, P=0.020) except in OD by post-virus infection (t=-1.98, P=0.052). tERPs signals in OD patients by sinonasal inflammation showed longer latency in the N₁ wave (t=2.15, P=0.036), but this difference was not observed in other OD patients (all P>0.05). tERPs signals were significantly correlated with the Sniffin' Sticks score, deficiency of oERPs and nasal minimum cross-sectional area (all P<0.05). Conclusions: OD patients show neurophysiologic deficits in trigeminal function. The absence of tERPs or lower amplitude in N₁ waves are the important characteristics of patients with OD.
Evoked Potentials/physiology* ; Female ; Humans ; Inflammation ; Male ; Olfaction Disorders/etiology* ; Retrospective Studies ; Smell/physiology* ; Virus Diseases/complications*

Animals integrate various environmental stimuli within the nervous system to generate proper behavioral responses. However, the underlying neural circuits and molecular mechanisms are largely unknown. The insulin-like signaling pathway is known to regulate dauer formation, fat metabolism, and longevity in Caenorhabditis elegans (C. Elegans). Here, we show that this highly conserved signaling pathway also functions in the integrative response to an olfactory diacetyl and a gustatory Cu(2+) stimuli. Worms of wild-type N2 Bristol displayed a strong avoidance to the Cu(2+) barrier in the migration pathway to the attractive diacetyl. Mutants of daf-2 (insulin receptor), daf-18 (PTEN lipid phosphatase), pdk-1 (phosphoinositide-dependent kinase), akt-1/-2 (Akt/PKB kinase) and sgk-1 (serum- and glucocorticoid-inducible kinase) show severe defects in the elusion from the Cu(2+). Mutations in DAF-16, a forkhead-type transcriptional factor, suppress the integrative defects of daf-2 and akt-1/-2 mutants. We further report that neither cGMP nor TGFβ pathways, two other dauer formation regulators, likely plays a role in the integrative learning. These results suggest that the insulin-like signaling pathway constitutes an essential component for sensory integration and decision-making behavior plasticity.
Animals ; Caenorhabditis elegans ; genetics ; physiology ; Caenorhabditis elegans Proteins ; genetics ; physiology ; Chemotaxis ; genetics ; physiology ; Copper ; physiology ; Cyclic GMP ; genetics ; physiology ; Diacetyl ; metabolism ; Insulin ; metabolism ; Longevity ; Signal Transduction ; Smell ; genetics ; physiology ; Taste ; genetics ; physiology ; Transforming Growth Factor beta ; genetics ; physiology

BACKGROUNDSubjective olfactory tests are easy to perform and popularly applied in the clinic, but using only these, it is difficult to diagnose all disorders of the olfactory system. The olfactory event related potentials technique offers further insight into the olfactory system and is an ideal objective test. This analysis was of subjective and objective data on the olfactory function of twelve patients with loss of smell associated with an upper respiratory infection (URI).

METHODSWe tested the twelve patients with URI induced olfactory loss by medical history, physical examination of the head and neck, olfactory tests and medical imaging. Olfactory function was assessed by Toyota and Takagi olfactometry including olfactory detection and recognition thresholds and olfactory event-related potentials (OERPs) recorded with OEP-98C Olfactometer.

RESULTSAn unusual phenomenon was observed in five patients in whom the subjective detection and recognition thresholds were normal, while the expected OERPs were not detectable.

CONCLUSIONSWe suggest that the discordance between olfactory psychophysical measurements and OERPs might be the results of abnormal electrophysiology related with olfactory neuropathy caused by viral URI. In addition, the measurement of OERPs might play a significant role in evaluating olfactory dysfunction.

Adult ; Evoked Potentials ; Female ; Humans ; Male ; Middle Aged ; Olfaction Disorders ; diagnosis ; Respiratory Tract Infections ; complications ; Sensory Thresholds ; Smell ; physiology

The study of neuronal activity with low frequency has shown an increasing interest for its greater stability and reliability recent years. One challenge in analyzing this kind of activity is to find similarities and differences between signals efficiently and effectively. The traditional analysis methods, such as short-time Fourier transform, are easily obscured by background noises and often involve a large number of parameters. Therefore, this paper introduces a novel time-frequency analysis method based on wavelet transformation and half-ellipsoid modeling to extract instantaneous frequency and instantaneous phase information. This method overcomes some shortcomings of conventional time-frequency analysis. In this method, wavelet transformation is used to provide high-level representations of raw signals, and parsimonious half-ellipsoid models are used to extract changes in time domain and frequency domain of neural recordings. The method was validated to local field potentials (LFPs) of olfactory bulb of anesthetized rats during three different odor stimuli. The results suggested that this method could detect odor-relevant features from olfactory signals with large variability. The Odors then were classified with support vector machine (SVM) algorithm and the classification accuracy reached 79.4%.
Algorithms ; Animals ; Evoked Potentials ; Fourier Analysis ; Odorants ; analysis ; Olfactory Bulb ; physiology ; Rats ; Reproducibility of Results ; Smell ; physiology ; Support Vector Machine ; Wavelet Analysis