Filtration of sensory input occurs at the organ level?
While browsing, I came across these three articles independently of each other. Perhaps it’s the new issue of Japanese Journal of Taste and Smell Research?
Here’s an interesting bit from the MSNBC article:
Wysocki, a study co-author, said the research could point to a “chemical communication” subtext between the sexes that enables men and women to coordinate their reproductive efforts subliminally.
Compare that with the BBC article:
Jeannette Haviland, who also worked on the research, suggested that hormones in the body odour of the young might act as a signal of aggression. Hormonal changes in old age, she said, were likely to make the odour of the elderly, particularly women, signal approachability.
So it’s clear: During “that time of the month” women are feeling bad, so they pick a fight with their man or men in general to enhance his agressive smell, thereby cheering themselves up a little. I smell a conspiracy!
With further study it became clear that growth factors in saliva and nasal mucus influenced stem cell development in both taste and smell systems. Dr. Henkin discovered, isolated, and sequenced growth factors responsible for development and maintenance of stem cells in the taste and smell systems and, thereby responsible for taste and smell function since these stem cells were the progenitor cells for all taste bud and olfactory epithelial cell anatomy, respectively. He discovered that the parotid glands in the mouth and the nasal serous glands in the nose secrete these growth factors into saliva and nasal mucus, respectively. These growth factors act on stem cells in the taste and smell systems through paracrine effects similar in some ways that hormones secreted from various glands in the body into blood influence metabolism through endocrine effects.
So endocrine and paracrine signalling is important for smell and taste function and development. I don’t know if any of the cited research addresses whether the signalling affects smell and taste function in the differentiated epithelia, or if the functions are limited to development, acting only on the stem cells. I am reminded of some research that suggested a role for new cell synthesis in memory formation, and of the way your house smells different when you come back from a long vacation. I’ve realized that cat owners often don’t realize that their houses quite frankly stink, and perhaps they don’t, to them, because of changes in the olfactory epithelia. This is mostly ignorant speculation since I don’t know much about how smell works on the molecular level, but there has to be something for smell that allows us to weed out extraneous input to focus on the ones most important to us, and it doesn’t all have to be done in the brain. Aside, I speculate that it’s because smell nerves don’t go through the thalamus on the way to the brain that smell has such powerful ability to evoke memory. Check out what cognitive psychology has to say about processing of input information. I’ll sum this up with the following hypothesis: All senses are filtered of repetitive input at the organ level, as well as the brain level.