We are not detectives, just as a Super – but also for the people of the sense of smell has an important meaning. He warns us of "stinking" hazards, such as spoiled food, but also pleasant experiences: pleasure and joy are also linked to the nose sense. People who suffer from a loss of ability to perceive smell, called anosmia, can get, this is often a subtle meaning to feel. In the Wake of the Corona pandemic, the issue of sense of smell consists of two different reasons, has received more attention: A characteristic early symptom of Covid-19 is the loss of the sense of smell, studies have shown. Other studies have shown that dogs can sniff out the infection in humans. Because Corona-patients seem to develop a characteristic smell that can identify the four-legged animals, with their fine noses.

"Against this Backdrop, the importance of a better understanding of the mechanisms of odor perception is clear," says Edmund Chong from the Neuroscience Institute at NYU Langone Health in New York. "The research could be the method to treatment or lead instruments in the detection of diseases," said the scientist. He and his colleagues investigate the neural processing of Smell impressions in the Olfactory center of the brain of mammals – the so-called olfactory bulb.

A smell is like a melody

Previous studies have shown that odor molecules to receptor cells in the nose to electrical signals, Vera, are sent to specific nerve bundles (Glomeruli) in the olfactory bulb. It is known that the timing and sequence of Glomeruli activation for each odor unique. Specifically: the scent of roses produced, for example, a significantly different signature of Glomeruli activation than, for example, the smell of sweat. The signals are routed cortex of the Glomeruli from then to the brain, where the reactions or memories associated with the smell to be activated.

explain How the researchers, you can imagine the odor signature to the Glomeruli as a melody. The order of the notes and sound duration of a result, we recognize a familiar tune. Similarly, the pattern of activation of the Glomeruli leads to the detection of an odour. In the context of the study, the researchers investigated the question as to what degree the change in the pattern of a smell is still discernible. Transferred to the image of the melody, this corresponds to a change in the sequence or the length of the beeps – to we do not more than is known be able to identify.

For their study, the researchers mice from a genetically took advantage of changes in the breeding line, their brain cells specifically activate: you respond to the fine pulses of light - a technique known as Optogenetics. Thus, it is possible, through the impulses in the olfactory bulb of the animals artificially, the pattern of a scent-perception trigger. The researchers trained their animals to associate a on the light-activation of six Glomeruli-based Signal with a reward: If they took this "Phantom smell", and they pressed a lever, and got something to drink.

When you operated the lever to the activation of another set of Glomeruli - i.e., after the Simulation of a other smell there was, however, not a reward.

What defines a specific odour signature?

After the Training, the researchers altered the Timing and the mixture of Glomeruli activation to determine the extent to which the mice interpreted the stimuli as the Signal-to-smell. For example: If the beginning of the signal within each of the odor-determining Glomeruli-Sets changed, there was a 30 percent decrease in the ability of mice to interpret the odor signal as the known triggers. The changes of the last few Glomeruli in each set led only to a decrease in the accurate perception of Odor by five percent. This, therefore, corresponds to the Start - or end-notes in a melody, the scientists explain.

"Now that we have a model for the breakdown of the timing and the order of the Glomeruli-activation, we can investigate the minimum number and type of Stimuli, the olfactory bulb is required, in order to identify a certain smell," concludes Co-author Dmitry Rinberg. "This brings us closer to the answer in our area of expertise long-asked question of how the brain sensor extracted information to behaviour,“ said the scientist finally.

source: Neuroscience Institute, NYU Langone Health, special articles: Science, doi: 10.1126/science.aba2357

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Date Of Update: 18 June 2020, 20:26