Researchers from the Stowers institute for Medical Research have traced individual odor molecules in the brain to produce a new type of how our olfaction works. While once thought to cluster related smells, researchers have know discovered that the mind reacts to smells in a broader sense.
Previous research has revealed that the brain handles the senses in a very orderly way.
Stuff that we touch were regarded as mapped together within the somatosensory cortex, stuff that we heard were mapped together in the auditory system, and stuff that we taste were mapped together within the gustatory cortex. The olfactory cortex handles stuff that we smell, but new information suggests that this system may respond to smells differently than ever before thought.
Instead of group chemically-related smells together within the olfactory system, the smells were mapped everywhere in the system.
“When we mapped the person chemical options that come with different odorants, they mapped all over the olfactory bulb, which processes incoming olfactory information,” says Associate Investigator C. Ron Yu, PhD, who led the research published in this week´s online edition of the Proceedings of the Nas (PNAS).
“From the animal´s perspective which makes perfect sense. Caffeine structure of an odor molecule isn’t what´s vital that you them. They would like to find out about their environment and associate olfactory information with food or any other relevant information.”
As we smell things, nasal receptors send an electrical signal up to glomeruli within the olfactory bulb. The pattern that these glomeruli send and receive signals towards the olfactory system was considered to represent specific odors.
This hypothesis on how the brain handles odor have been widely accepted, but it had not been accurately mapped. Recent research and available technologies have shown that this process breaks down in a very fine level, thus requiring a more fine-tuned or more critical look in the olfactory map.
Yu and the team generated a line of super sensitive transgenic mice and equipment sophisticated enough to provide hundreds of odor stimuli one mouse.
Within their tests, they learned that certain odors did activate within a specific and distinct part of the olfactory bulb. Other odors, however, signaled glomeruli in a variety of regions of the bulb. Some odors even intermingled within the olfactory bulb, suggesting the glomeruli haven´t yet evolved to detect the specific chemical shapes of certain odors.
This finding didn’t surprise lead author from the study Limei Ma, PhD, as there are thousands of odors.
“Many of them might be really novel towards the organism, something they never encountered before,” she says. “The machine should have the power to recognize and encode anything.”
The research shows that the “chemotopic” hypothesis how the mind responds to different odors might not be completely accurate. They has now devised a “Tunotopic” hypothesis on the olfactory system. This means individual glomeruli are “tuned” to get certain odor chemical molecules, and therefore can send these to different areas of the olfactory bulb. The team believes this kind of hypothesis can be used to describe the way the brain handles the other senses too.
“When you have a new chemical synthesized, like new perfumes and food flavors, you don´t need to create new brain regions to react to it,” Ma said in the press release. “That which you do is make use of the existing receptors to sense all these chemicals after which inform your brain whether this is novel, whether it´s similar, or whether it´s something really strange.”