Researchers at the University of Fukui, in Japan, conclude in a new study that the smells perceived in childhood leave an indelible mark for the rest of life. In this way, they condition social behaviors and decisions made in adulthood. In the same sense, they can create the right scenario for the emergence of pathologies such as autism or attachment disorder, a mental disorder caused by lack of affection during childhood.
Exposure to environmental information during a critical period early in life is important for forming sensory maps and neural circuits in the brain. In mammals, early exposure to environmental factors, such as odors, is known to create a strong imprint and affect perception and social behavior later in life.
According to a Press release, the researchers found that certain inappropriate olfactory stimuli could even cause neurodevelopmental disorders, such as autism spectrum disorders (ASD) and attachment disorders (AD). In these cases, bonding relationships, personality development and social relationships in general are notoriously affected.
In addition, research sheds light on oxytocin treatments, indicating that they could be effective in preventing various disorders if applied at the right time. Specialists believe that this approach is more effective in newborns, since it optimizes the results at the time of improving the deterioration of social behavior.
Molecules and olfactory imprints
How did the scientists arrive at these conclusions? In their study, published in the journal eLife, they focused on determining how the olfactory imprinting mechanism works during the critical period in mice. In principle, they found three molecules involved in this process: Sema7A, Plexin C1 and oxytocin, a peptide better known as the “love hormone.”
These molecules interact and generate various chemical reactions, favoring imprints or traces around odors. There is also a double mechanism: on the one hand, innate responses to some olfactory stimuli that induce certain behaviors and, on the other, behaviors marked by experience, which generate traces in memory from exposure to certain odors.
In one of their experiments, the specialists found that in newborn mice the olfactory imprint produced by experience and housed in memory predominates over innate reactions around a specific smell. This means that by stimulating these “learned” traces or imprints it would be possible to nullify innately generated behaviors.
The role of oxytocin
In addition, the scientists found in their research that the modifications introduced in the indicated molecular mechanisms can change the olfactory imprints, generating positive or negative responses to each stimulus. In this way, if similar effects are verified in humans, it would be possible to treat aversion to certain odors with different strategies, mainly those capable of triggering neurodevelopmental disorders.
As indicated above, oxytocin could play a key role, imposing the positive quality of odor memory when released in infants. Consequently, it could be used in babies to promote this positive response to certain smells, preventing neurodevelopmental disorders.
Now, scientists will seek to determine the way in which the processes verified in rodents are carried out in humans. If similar reactions were verified, a new hope would be born in the treatment of pathologies related to behavioral and personality disorders.
The Olfactory Critical Period is Determined by Activity-Dependent Sema7A/PlxnC1 Signaling within Glomeruli. Nobuko Inoue, Hirofumi Nishizumi, Rumi Ooyama, Kazutaka Mogi, Katsuhiko Nishimori, Takefumi Kikusui and Hitoshi Sakano. eLife (2021). DOI: https://doi.org/10.7554/eLife.65078
Photo: Richard Ecsedi en Unsplash.
Eddie is an Australian news reporter with over 9 years in the industry and has published on Forbes and tech crunch.