We always seem to remember the smell of things for a long period of time. We associate many events with various smells. Some smells make us alert, others entice us and still others make us feel relaxed. There are smells that make us feel angry, upset and disturbed. Emotions, both positive and negative are linked to the various smells that we have experienced in our lives. Thus it is possible to elevated moods and to be depressed due to the different fragrances that we encounter in our day to day lives. We associate people with the perfumes that they use.

The reason for this is that our sense of smell is directly connected to the center of memory in the brain through the olfactory system. The olfactory cortex has a direct connection with the amygdala - hippocamal of the limbic system.

Limbic system

The limbic system is a word for a set of brain structures including the hippocampus and amygdala and frontal thalamic nuclei and a limbic cortex that support a selection of functions including emotion, activities and long term memory. The structures of the brain described by the limbic system are personally associated with the olfactory structures. The term "limbic" comes from Latin limbus, sense "border" or "belt".

The limbic system operates by influencing the endocrine system and the autonomic nervous system. It is extremely interconnected with the nucleus accumbens, the brain's happiness center, which plays a role in sexual arousal and the "high" derived from certain leisure drugs. These responses are heavily modulated by dopaminergic projections from the limbic system. In 1954, Olds and Milner found that rats with metal electrodes implanted into their nucleus accumbens repeatedly pressed a lever activating this region, and did so in preference to eating and drinking, eventually dying of exhaustion.

They are the only sensory nerves directly exposed to the environment. The other sensory nerves go first through the thalamus, while the olfactory nerves send messages to areas linked to memory.

The sense of smell is second most important sensory organ after sight. We remember things very clearly things that are associated with smells, even after a long time. An example is the fresh smell of baked bread coming from a bakery as we pass by. Our memory can remember it much later. The sense of smell is also linked with the sense of taste. We relish the smell of all the things that we eat. Each food item has a unique smell, too. Even when we are sleeping, our memory can recall any smell that we sensed earlier. The sense of smell cannot be turned off. It is ever present.

Almost seventy percent of our emotions are based on the things that we smell. Smells have the power of relieving stress, increasing alertness and improving the quality of work. This can be used in work places for the extra benefit for the staff and increase productivity. All this helps in improving the quality of life of the workers.

Various experiments done on rats and other animals show that their sense of smell is very much a part of their learning process. A study done on rats by Francis Darling and Burton Slotnick in 1994 showed that rats learnt to avoid drinking water in a tube mixed with quinine hydrochloride and an odorant very quickly, within one or two trials. In another W. Thomas Tomlinson in 1991 made a study of hamsters. One group was given liquid diet. The other group had normal diet. The one with normal diet located the food that they had to eat, showing that memory and odor senses are linked. A study was made on patients with "Korsakoff's syndrome", severe memory loss in human beings. The patients seemed top have less of odor memory loss compared to other forms of memory, showing that odor memory is different from other types of memory.

Wernicke-Korsakoff Syndrome

Wernicke's encephalopathy is a degenerative brain disorder caused by the lack of thiamine (vitamin B1). It may result from alcohol abuse, ietary deficiencies, prolonged vomiting, eating disorders, or the effects of chemotherapy. Symptoms include mental confusion, vision impairment,stupor, coma, hypothermia, hypotension, and ataxia. Korsakoff's amnesic syndrome-a memory disorder-also results from a deficiency of thiamine,and is associated with alcoholism. The heart, vascular, and nervous system are involved. Symptoms include amnesia, confabulation, attention deficit, disorientation, and vision impairment. The main features of Korsakoff's amnesic syndrome are the impairments in acquiring new information or establishing new memories, and in retrieving previous memories. Although Wernicke's and Korsakoff's may appear to be two different disorders, they are generally considered to be different stages of the same disorder, which is called Wernicke-Korsakoff syndrome. Wernicke's encephalopathy represents the "acute" phase of the disorder, and Korsakoff's amnesic syndrome represents the "chronic" phase.

The olfactory sensation is the slowest of all senses but it is the sense that stays for a longer period of time. Women seem to have a keener sense of smell than men. Each individual has a different smell and it is unique to that person. It can also be called odor identity or smell "fingerprint'. Many experiments have been done to prove the connection between memory and the organ of smell. Neurological imaging techniques will make us understand the better the way the memory of all beings on this earth works.

Almost seventy percent of our emotions are based on the things that we smell. Smells have the power of relieving stress, increasing alertness and improving the quality of work. This can be used in work places for the extra benefit for the staff and increase productivity. All this helps in improving the quality of life of the workers.

Various experiments done on rats and other animals show that their sense of smell is very much a part of their learning process. A study done on rats by Francis Darling and Burton Slotnick in 1994 showed that rats learnt to avoid drinking water in a tube mixed with quinine hydrochloride and an odorant very quickly, within one or two trials. In another W. Thomas Tomlinson in 1991 made a study of hamsters. One group was given liquid diet. The other group had normal diet. The one with normal diet located the food that they had to eat, showing that memory and odor senses are linked. A study was made on patients with "Korsakoff's syndrome", severe memory loss in human beings. The patients seemed top have less of odor memory loss compared to other forms of memory, showing that odor memory is different from other types of memory.