The sense of scent is the least known of all sensory systems. Although it attracted perfume producers and wine specialists, it struggled to draw scientists.
Unlike the sense of sight and sound, the sense of smell becomes fully operative at birth. Humans and animals communicate with their surroundings by smelling. Infant rats grow to prefer the scent of their mother's nipples to the first week of life.
Ewes can discern the smell of their own lambs from the rest of the flock within two to four hours of birth. Animals also secrete pheromones in order to attract mates and promote sexual activity or aggression in order to reproduce their species.
In humans, the scent and voice of mothers during the first three years of their children (not later) is crucial to their emotional health in their adult years. If the boy struggles to understand, bind, and familiarize himself with the mother's voice and scent, he will not be emotionally close to her as he gets older.
A fragrance helps us identify a specific person, location or occurrence. It can make us indignant or passionate, pitiful or beautiful, anorexic or gluttonous.
Are you getting stressed out? Why don't you try aromatherapy? It could make you more relaxed.
When you can't smell, you're in trouble. Erratic smell can contribute to eating disorders, psychiatric issues, asthma, and Alzheimer's disease.
Anosmics (people with no sense of smell) can not distinguish typical smells such as baby powder, sugar, cocoa , coffee, mothball, peanut butter, and soap. They often struggle to react properly to harmful odors such as rotten food, smoke or natural gas such as ethyl mercaptan, a chemical applied to liquefied petroleum gas ( LPG) to detect leakage.
How are odors getting to the brain and influencing our behavior?
Smelling occurs in the olfactory epithelium about 7 cm up into the nose. While it's only a little bigger than a 5 cm SIM card, the epithelium is packed.
With 40 million detectors called visual olfactory neurons. A very vulnerable place, in fact!
Olfactory epithelium can detect harmful gas ozone at approximately 10 molecules per billion; citrus odor, or D-limonene, at 15 molecules per billion; and ethanol at 2,000 molecules per billion in room air. These just imply that a very small quantity of these substances is required to awaken the "smelling" cells.
The odor signals are projected to the olfactory bulb, going through the cribriform plate or gaps in the skull. Here, neurons that pick up identical odor signals are grouped together and packed together through mitral (Latin for "turban") and tufted cells. This method intensifies the identification of odors as well as the effective relay of odor signals to the brain.
Shape of packaged neurons into glomeruli (Latin for "ball") that make up the olfactory tract of the olfactory cortex in the temporal lobe of the brain. The olfactory cortex consists of brain structures such as piriform cortex, amygdala, and hypothalamus, to name a few. These regions are responsible for our smell, emotion, age, circadian rhythm, memory, and internal homeostasis. When they communicate with each other, it helps us respond memorably to a certain smell.
The Miracles of the Fragrance
After the phase of olfactory cortex, identify and respond to odors, projections are further transferred to higher brain centers — the cerebral cortex. Here, initial odor reactions are analyzed, perpetuated, and long-term, if necessary, ready for retrieval at any moment.
Interestingly, unlike cranial nerves for eyes , ears, mouth, and touch, the olfactory nerve does not move through the thalamus, the central station of the brain. Scientists have been unable to provide a plausible reason for this. Yet I agree the God knows best. And when the thalamus is weakened and all the other senses cease functioning, the sense of smell remains functional.
Most notably, in the cerebral cortex, the orbitofrontal cortex (OFC) is a particular area that regulates appetite and food consumption. Neuroimaging experiments indicate that the neuron in the OFC is extremely sensitive when a human smells, eats, or sees food. The intensity of the response depends on the degree of hunger and perceived value, such as price or appeal, of the food.
In other words, the fuller the individual and the lower the importance of the food, the dimmer is the reaction of the OFC neurons to the scent and sight of specific food products. Many with dementia, though, with their OFC nerves weakened and dead, appear to overeat or consume binge food despite the knowledge of being whole. Healthy OFC is therefore essential for the tight regulation of appetite.