Modeling odor processing in microbes, mice, and mankind

In Human pheromones and food odors: epigenetic influences on the socioaffective nature of evolved behaviors, I conclude that olfaction and odor receptors provide a clear evolutionary trail that can be followed from microbes to man. The representation of this evolutionary trail in my model appears to equate with a 3/19/12 report from the Stowers Institute for Medical Research about the article: “Distributed representation of chemical features and tunotopic organization of glomeruli in the mouse olfactory bulb.” As indicated in their report New model show how the brain is organized to process odor information, the difference between my model and this “new model” may lie only in across-species comparisons, and my extension of a mammalian model to man.

In my model what they call “tuning” equates with the effects of nutrient chemicals that “calibrate” the survival of individual organisms. This “calibration” is followed by the effects of pheromones that “standardize” and “control” speciation. Thus, two different types of chemical stimuli are directly linked both to intracellular signaling and to the stochastic gene expression that is required for de novo olfactory receptor genes.

Whether it is called tuning, calibration, control, or standardization, the direct effect of chemical stimuli on intracellular signaling and gene expression occurs as other sensory input is processed. Simply put, cause and effect are directly linked to chemical stimuli and gene expression at the same time other sensory input is processed. Responses to other sensory input from the environment are conditioned to occur via the direct effect of nutrient chemicals and pheromones on intracellular signaling and gene expression.

The molecular basis of learning and memory is a secondary underlying theme of my model. In mammals, for example,  food odors, pheromones, and movement/exercise have been linked to intracellular signaling and stochastic gene expression in neurosecretory cells of brain tissue, and to luteinizing hormone and hippocampal neurogenesis. For additional information on the role of conditioning, learning, and memory see Woodson, 2012). It is important to note that conditioning, learning, and memory occur without other sensory input in organisms with no olfactory bulbs, ears, or eyes. And, it is this “tuning” that allows for the evolution of species with olfactory bulbs, ears, and eyes.

When it comes to whatever behavior they attempt to explain, those who have no model for the evolution of different species may equate the importance of visual or auditory input with the importance of olfactory/pheromonal input. But there is no mammalian model for the evolution of human behavior that does not first need to consider the effects of food odors and pheromones on hormones. In this context we can forget the analogies, metaphors, definitions, and allegorical representations. Clearly the focus must be on evolution’s sensory drive: olfaction. Those who would rather make everything about the development of human sexual behavior seem to depend on visual and auditory input should first be asked: “Is there a model for that?”

Author: James Kohl

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