Pheromone-induced Fos expression directly linked to social odor and suckling correlated with other odors and survival
- Pheromone-induced odor learning modifies Fos expression in the newborn rabbit brain
Article excerpts: "A single pairing of the odorant with the MP was then sufficient to rapidly induce a differential activation of brain regions assumed to play a role in associative processes, such as the amygdala and the posterior piriform cortex, during subsequent re-exposure to the learned odorant."
"...learning-induced neuronal rearrangements that link the perception of an initially neutral odorant with motor responses related to the vital need of sucking."
Modified Fos expression indicates the direct epigenetic effect of the MP (i.e., the Mammary Pheromone) on intracellular signaling and stochastic gene expression that is required for adaptive evolution. It's an innate (i.e., unlearned) response. The effect of the pheromone is the same as the effect of nutrient chemicals except for species specificity, which is required to link the genetically predisposed response to mammalian behaviors that are required for species survival in species from microbes to man (e.g., all of them that require nutrient chemicals for individual survival and the metabolism of the nutrient chemicals to pheromones that control reproduction).
The attempt below to make the response to pheromones one that must be learned is a misrepresentation of what is already known about cause and effect at the molecular level by those who are informed enough to know better.
Excerpted from below: "Prevailing thought has been that pheromones –chemicals that trigger an innate behaviour – drove the suckling response as an automatic behaviour. The new work determines that, in mice, the smells must be learned before the behaviour can occur."
If the genetically predisposed response to pheromones required learning in any species, it seems unlikely to me that there would be more than one species. Is there a model for that? Could a random mutation concurrently cause a change in the genome and another change in the genetic predisposition of an organism to respond to it sensory environment in the context of adaptive evolution as is required where adaptive evolution is nutrient chemical-dependent and reproduction is pheromone controlled?
What if the first species had to learn how to respond to the pheromones of conspecifics before behaving appropriately in the context of that species -- species-specific behaviors?
James V. Kohl
Medical laboratory scientist (ASCP)
Kohl, J.V. (2012) Human pheromones and food odors: epigenetic influences on the socioaffective nature of evolved behaviors. Socioaffective Neuroscience & Psychology, 2: 17338.-Babies learn mum's unique odourOctober 4th, 2012 in Biology / Plants & Animals
Researchers show for the first time that a mammal begins to suckle its mother's milk through a learned response built on learning her unique combination of smells. When it is born, the newborn is exposed to the smell of its mother's amniotic fluid and the baby then responds to those smells to feed.
Prevailing thought has been that pheromones –chemicals that trigger an innate behaviour – drove the suckling response as an automatic behaviour. The new work determines that, in mice, the smells must be learned before the behaviour can occur.
Suckling is a critical step for survival in mammals, which are defined by giving birth to offspring that need to feed from their mother's milk. The newborn must begin to feed soon after birth or it will die. It is a crucial, defining behaviour in mammals and offers researchers an opportunity to investigate the biology of instinct.
Previous research into suckling has shown that European rabbit mothers use a pheromone to initiate suckling in their newborn babies. This led most scientists to think that all mammals were likely to use the same mechanism. Keen to discover the pheromone involved in other mammals, the team chose the mouse because they have a parenting style similar to that of humans, nurturing and caring for their young.
"We were expecting to find a pheromone controlling suckling in mice, but we found a completely different mechanism at work," says Dr Darren Logan, lead author of the study from the Wellcome Trust Sanger Institute. "We have shown for the first time that it is not a pheromone response in mice, but a learned response, founded on a mix of odours: the unique signature smell of the mother."
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For newborn mice to suckle for the very first time and survive, they depend on a signature blend of scents that is unique to their mothers. The findings, published online on October 4 in Current Biology, a Cell Press publication, reveal that mom’s natural perfume consists of odors emitted from the amniotic fluid, which served to nourish and protect those young mice before they were born. Credit: Current Biology, a Cell Press Journal, Logan et al.To discover the smells involved in initiating suckling, researchers introduced newborn mice delivered by Caesarean section to breasts that had been washed clean and then soaked in one of the fluids that a baby would first inhale at birth. These included amniotic fluid, the mother's saliva (from being licked clean), breast milk and urine. Only the breasts that smelt of the mother's amniotic fluid initiated suckling.
The team then tested for the presence of a pheromone in the amniotic fluid. They fed pregnant mice strong smelling foods, such as garlic, to change the signature odour of the mother. If a pheromone was involved, the garlic would have no effect on suckling. In fact only those mice that had previous exposure to the amniotic fluid with the strong smell from their mother were able to feed successfully, proving the signature odour must be learned.
"Our work shows us that there is no species-wide pheromone that makes newborn mice feed, but that the mouse pups are actually learning their mother's unique and variable mix of smells at birth," explains Associate Professor Lisa Stowers, senior author from The Scripps Research Institute. "So, although the suckling response may look like a pheromone-mediated behaviour, it is actually initiated through a fundamentally different process."
Supporting evidence for this conclusion comes from genetic research conducted by the team. They found that mice who lack a critical gene in the pheromone-detecting region of the nose, called the vomeronasal organ (VNO), were able to locate the mother's nipple and to suckle. In contrast newborn mice who lacked the ability to smell regular smells, detected in a region called the main olfactory epithelium (MOE) struggled with feeding.
"This is a neat study which shows the value of studying the development underlying an apparently 'innate' behavior." Dr Tristram Wyatt of the University of Oxford. "The surprising result is that mouse pups use the individual odours of the mother to find their first feed. It is a reminder of the way that evolution uses whatever works: there is more than one way to find the first milk meal. The rabbit has a pheromone in the milk, humans may have one around the nipple, and mice learn the individual odour of their mother. All three enable the vital task of getting the newborn to suckle."
Learning a signature odour may be a critical component of other innate behaviours in mammals. Because humans also form an intensive, nurturing bond with their babies, it suggests that genetic manipulation of the ability to smell in mice will be a useful way to research the neural pathways involved in human instinctive behaviour.
More information: Darren W Logan, Lisa J Brunet, William R Webb, Tyler Cutforth, John Ngai, Lisa Stowers. (2012) 'Learned recognition of maternal signature odors mediates the first suckling episode in mice' Published in CurrentBiology, 4 October 2012: DOI: 10.1016/j.cub.2012.08.041
Provided by Wellcome Trust Sanger Institute
"Babies learn mum's unique odour." October 4th, 2012. http://phys.org/news/2012-10-babies-mum-unique-odour.html