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When odors activate the olfactory pathways that lead to the limbic portion of the brain they trigger the release of neurotransmitters that affect the brain and mental state of the individual in a variety of ways. Stimuli transmitted to the limbic system cannot be consciously blocked, so all olfactory stimuli influence our emotions. [10]
Neurologists have observed that olfactory dysfunction is a cardinal feature of several neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Most of these patients are unaware of an olfactory deficit until after testing where 85% to 90% of early-stage patients showed decreased activity in central odor processing ...
The vibration theory of smell proposes that a molecule's smell character is due to its vibrational frequency in the infrared range. This controversial theory is an alternative to the more widely accepted docking theory of olfaction (formerly termed the shape theory of olfaction), which proposes that a molecule's smell character is due to a range of weak non-covalent interactions between its ...
Glomeruli are important waystations in the pathway from the nose to the olfactory cortex and have been found to be critical for odorant signal transduction. The olfactory receptor neurons (ORN), which originate in the nasal epithelium express only one type of olfactory receptor (OR). These ORNs then project their axons to the olfactory bulb.
Odors enter the nose (or olfactory rosette in fishes) and interact with the cilia of olfactory receptor neurons. The information is sent via the olfactory nerve (CNI) to the olfactory bulb. After processing in the bulb the signal is transmitted caudally via the axons of mitral cells , and tufted cells in the lateral olfactory tract.
The antennal lobe is the primary (first order) olfactory brain area in insects. The antennal lobe is a sphere-shaped deutocerebral neuropil in the brain that receives input from the olfactory sensory neurons in the antennae and mouthparts. Functionally, it shares some similarities with the olfactory bulb in vertebrates. [1]
The olfactory trigone is a small triangular area in front of the anterior perforated substance. Its apex, directed forward, occupies the posterior part of the olfactory sulcus , and is brought into view by throwing back the olfactory tract .
Olfactory pathway, insects. Insect olfaction refers to the function of chemical receptors that enable insects to detect and identify volatile compounds for foraging, predator avoidance, finding mating partners (via pheromones) and locating oviposition habitats. [1] Thus, it is the most important sensation for insects. [1]