Stockholm [Sweden], October 16 (ANI): Researchers at Karolinska Institutet in Sweden have been able to study what happens in the brain when the central nervous system assesses an odor that represents danger.
The study indicated that negative odors associated with discomfort or discomfort are processed earlier than positive odors and trigger a physically avoidant response. The results of the study were published in the journal ‘Proceedings of the National Academy of Sciences’.
The ability to detect and react to the smell of a potential threat is a prerequisite for our and other mammals’ survival.
“The human avoidance response to unpleasant odors associated with danger has long been seen as a conscious cognitive process, but our study shows for the first time that it is unconscious and extremely fast,” said the study’s first author Behzad Iravani, a researcher at the Department of Clinical neuroscience, Karolinska Institutet.
The olfactory organ absorbs about five percent of the human brain and enables us to distinguish between many millions of different odors. Many of these odors are associated with a threat to our health and survival, such as chemicals and raw foods. Odor signals reach the brain within 100 to 150 milliseconds after inhalation through the nose.
All living organisms survive depends on their ability to avoid danger and seek rewards. In humans, the sense of smell seems particularly important in detecting and responding to potentially harmful stimuli.
It has long been a mystery exactly what neural mechanisms are involved in the transformation of an unpleasant odor into avoidant behavior in humans. One reason for this is the lack of non-invasive methods for measuring signals from the olfactory bulb, the first part of the rhinencephalon (literally “nasal brain”) with direct (monosynaptic) connections to the important central parts of the nervous system that help us detect and remember threatening and dangerous situations and substances.
Researchers at Karolinska Institutet have now developed a method that for the first time has made it possible to measure signals from the human olfactory lamp, which treats odors and in turn can transmit signals to parts of the brain that control movement and avoidance.
Their results are based on three experiments in which the participants were asked to rate their experience of six different scents, some positive, some negative, while the electrophysiological activity of the odor lamp was measured when they responded to each of the odors.
“It was clear that the light bulb reacts specifically and quickly to negative odors and sends a direct signal to the engine bark within about 300 ms. The signal causes the person to unknowingly lean back and away from the odor source,” says the study’s former author Johan Lundstrom, associate professor at the Department of clinical neuroscience, Karolinska Institutet.
“The results suggest that our sense of smell is important for our ability to detect dangers in our vicinity, and much of this ability is more unconscious than our response to danger conveyed by our visual and auditory sensations,” he added.
The study was funded by the Knut and Alice Wallenberg Foundation, the National Institute on Deafness and Other Communication Disorders and the Swedish Research Council. There are no reported conflicts of interest. (ANI)
Source: sn.dk