The vomeronasal organ (VNO) specializes in detection of chemosignals, mainly pheromones, which control social communication and reproduction in many mammals. These pheromones must solubilize with nasal fluids before entering the VNO, and it was suggested that they are delivered to and cleared from the VNO by active pumping. Yet, the details of this pheromone delivery process are unclear. In this study, we first constructed a high-resolution 3D morphological image of the whole adult mouse snout, by using ultra-high-resolution micro-CT. We identified a net of micro tunnels starting from the nostrils and extending around and through the VNO. These micro tunnels connect the nasal cavity with the VNO and the oral cavity via the nasopalatine ducts (NPD). Other micro tunnels connect the nasal cavity to the main olfactory epithelium. We next demonstrated that physical obstruction of the NPD severely impairs the clearance of dissolved compounds from the VNO lumen. Moreover, we found that mice with blocked NPD display alterations in chemosignaling-evoked neuronal activation in brain regions associated with the vomeronasal system. Finally, NPD-blocked male mice exhibit reduced preference for female chemosignals, and impaired social interaction behavior. Taken together, our findings indicate that the NPD in mice are connected to both the nasal and oral cavity, serving an essential role in regulating the flow of soluble chemosignals through the VNO, and are required for proper pheromone-mediated social communication.

Objective Conductive olfactory losses mainly involve obstruction of the olfactory cleft (OC) and diminished OC airflow. This study investigated the association between abnormal nasal structure and OC airflow. Methods A systematic search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis to identify studies on the effect of the nasal structure on the OC airflow and olfaction. Results A total of 11 studies were included. Nasal vestibule morphological variabilities directly impact the transport of molecules in odorant-laden air to the OC. A greater airflow vortex and a narrower vestibule region intensified the airflow vortex toward the olfactory region. Middle turbinectomy significantly increased the average flux to the OC. The location of the major airflow and airflow velocity maxima shifted towards the OC in patients with septal deviation. The airflow has been redirected into the upper part of the nasal airway in patients with inferior turbinate hypertrophy. For patients with unilateral cleft lip, unilateral nasal airflow on the cleft side has a lower rate and flow. The mean velocity in the posterior OC correlated well with olfaction compared to that in the anterior OC. The nasal polyps (NP) within the middle meatus increased the olfactory airflow but did not enhance the olfaction. NP in the olfactory region or anterior to the olfactory region significantly decreased the olfactory airflow and olfaction. Furthermore, obstruction of the OC did not change the nasal patency. When the OC shape presented with a stenotic slit or lumen structure among patients with conductive olfactory dysfunction without NP, the inspiratory velocity and flow rate within OC were significantly lower than in the healthy control group. Conclusion Various nasal structural factors affect patterns of OC airflow and olfaction. Identifying the related airflow-limiting structures may promote the comprehensive evaluation of conductive olfactory losses in patients with olfactory dysfunction.

Binding of airborne odour molecules to olfactory receptors at the top of the nasal cavity gives rise to our rich olfactory experience. Whether airflow plays a role in human olfactory perception beyond the transportation of odorants is scantly known. Combining psychophysical measures with strict controls of nasal flow parameters, we demonstrate in four experiments that the perceived intensity of a unilaterally presented odour decreases systematically with the amount of contralateral nasal airflow, in manners that are independent of odour flow rate, nasal pressure, perceived sniff vigour or attentional allocation. Moreover, the effect is due to the sensed rather than the factual amount of nasal flow, as applying a local anaesthetic to the contralateral nostril produces the same effect as physically blocking it. Our findings indicate that nasal flow spontaneously engages central olfactory processing and serves as an integral part of the olfactory percept in humans.

Airflow detection while smelling is a fundamental requirement for olfaction, yet the mechanisms underlying such multimodal processing in the olfactory system remain unknown. We report here that mice can accurately discriminate airflow in the absence of whiskers. Modulated sniffing and refined calcium signaling in the olfactory bulb inhibitory network during olfactory anemo-discriminations confirmed the orthonasal airflow information processing. Genetic perturbation of AMPAR function and optogenetic control bidirectionally shifted the anemo-discrimination learning pace, with contrasting phenotypes observed for odor learning, engagement of inhibitory circuits, and setting the optimal inhibition level for stimulus refinement. Enhanced learning caused by multimodal odor-airflow stimuli at subthreshold levels confirmed the heightened olfactory perception by mechanical stimuli. Our results thus explain the multimodality of olfaction and reveal the unexplored dimensionality of odor perception.

Improvement of olfaction in laryngectomized patients with the larynx bypass. Hyposmia following laryngectomy is an often recognized phenomenon. A larynx bypass device was used to determine whether this olfactory deficit could be reversed simply by restoring nasal airflow. Odorant detection thresholds and confusion matrix identification tests were administered to laryngectomy and normal comparison groups. Data on nasal airflow characteristics with and without the bypass were also analyzed. The results suggested that restoration of nasal airflow completely reversed the hyposmia for trigeminal nerve stimuli. However, the reversal of hyposmia was not complete for those odorants which primarily, if not exclusively, stimulate the olfactory nerve. This suggested that other factors may contribute to laryngectomy-induced hyposmia for olfatory nerve stimuli. Additionally, nasal airflow analysis revealed that confusion matrix identification scores were depedent upon inspiratory sniff flow rates with and without the larynx bypass. It is argued that rehabilitation for the laryngectomee should include efforts to restore and maintain preoperative olfactory acuity.

Effects of Nasal Ventilation on Cerebral and Pulmonary Function in Orally Intubated Patients The passage of air through the nasal cavity generates rhythmic oscillations transmitted by the olfactory bulb to the brain, which induces cerebral activation in functional areas and is associated with better cognitive performance compared to oral breathing. Consequently, the abolition of nasal ventilation in patients intubated via the orotracheal route could have deleterious effects on brain activity. Besides the loss of olfaction, the abolition of nasal ventilation could affect brain activity and respiratory control, consequently altering regional pulmonary ventilation. The hypothesis of the study is that nasal ventilation through the passage of humidified nasal airflow in patients intubated via the orotracheal route would be associated with modulation of cerebral electrical activity and tissue oxygenation and a modification of regional pulmonary ventilation. The effects of nasal ventilation on cerebral activity will be studied on orally intubated and sedated patients in six experimental conditions.

mechanoreceptors lined in their nasal cavity. It is suggested that the multi-ciliated cells around the rim of their nasal cavities generate a water flow to increase Communication occurs when an animal produces a signal and uses it to influence the behavior of another animal. A signal can be any behavioral, structural or physiological trait that has evolved specifically to carry information about the sender and/or the external environment and to stimulate the sensory system of the receiver to change their behavior. A signal is different from a cue in that cues Co… Crustaceans can release urine containing chemical signals anteriorly through a pair of nephron-pores and can also deposit pheromones on their body surface which are produced by their tegmental glands. Fish release pheromones through urine using their excretory pores and gills. Amphibians such as frogs and toads produced water-soluble pheromones using their breeding glands. Mammals such as dolphins release water-soluble pheromones in their excretions, while pinnipeds have scent glands around the vibrissae and hindquarters that are thought to produce pheromones. Chemical signals are detected using mechanoreceptors. Crustaceans have chemoreceptors on the antennules. They can sample chemical signals around them by flicking their antennas and by creating water currents that draw the chemicals in their surrounding towards them. Fish have mechanoreceptors lined in their nasal cavity. It is suggested that the multi-ciliated cells around the rim of their nasal cavities generate a water flow to increase chemical detection. Most semi-aquatic amphibians, reptiles and mammals have nose and tongues. On land, sea otters and pinnipeds often perform 'nosing' behaviors at prominent scent glands which indicate some level of detection of chemical signals. It was previously perceived that they do not undergo chemical communication underwater, as most of these animals close their nasal opening underwater and the semi-aquatic mammals are known to have reduced olfactory nerves, bulbs and tracts. However, it has been found that the semi-aquatic star-nosed mole and water shrew can detect chemicals underwater by exhaling air bubbles onto objects or scent trails and re-inhaling the bubbles which now carry the chemical signals back through the nose. Chemical signals are used for: