This finding, plus the fact that both types of stimuli produce reaction in olfactory nerve cells, which control how our brain perceives what we smell, explains why we sniff to smell something, and why our sense of smell is synchronized with inhaling.
"The driving force for such synchronization remained a mystery for more than 50 years," says senior author Minghong Ma, PhD, Assistant Professor of Neuroscience. "These results help us understand how the mammalian olfactory system encodes and decodes odor information in the environment."
Researchers tested two different types of stimulation on olfactory neurons in mice: chemical stimuli, such as those used in making perfumes that have almond-like and banana-like scents, and mechanical stimuli, that is pressure carried by air flow to the nostrils while breathing.
The group did this first by puffing a chemical stimulus into the nose. As expected, this produced a reaction in the olfactory neurons, the primary sensory neurons in the nose that perceive odors. Researchers then puffed a solution without the chemical stimuli into the mouse's nose. This also produced a similar, but smaller reaction in the olfactory neurons. By decreasing pressure of the non-odor solution, they also found that the reaction in the olfactory neurons was less, confirming that it was sensitive to mechanical stimulation.
When olfactory neurons respond to odor molecules, they transmit chemical energy into electrical signals, which then trigger a secondary molecular messenger cascade that generates electrical impulses to the brain, signaling that it is smelling something. The group discovered that chemical and mechanical stimuli both resulted in the same messenger molecule, cAMP, which acts like a gatekeeper of reactions in the olfactory neurons.
Although this study was conducted on a mouse model, the researchers tested two different parts of the nose, one that humans have and one that humans do not. The first, the septal organ, is a patch of smell-sensitive tissue on the septal wall of the nasal cavity. The second, the main olfactory epithelium, is a smell-sensitive tissue inside the nasal cavity.
The septal organ is only about 1 percent the size of the main olfactory epithelium and isn't shared by all mammals. Mice, for example, have a septal organ. Humans do not. But in this study, Ma's group found that 50 percent of the cells in the main olfactory epithelium are sensitive to physical stimuli, suggesting that mechanosensitivity of the olfactory sensory neurons exists in all mammals, even those like humans, without the septal organ.
The mechanosensitivity of our olfactory neurons has two possible functions, suggest the investigators. The first is that it increases our ability to smell, enhancing the detection of odorous molecules in the air. The second is a peripheral drive in the brain to synchronize rhythmic activity, which is the concurrent firing of neurons in the olfactory bulb with breathing.
"The mechanosensitivity may increase the sensitivity of our nose, especially when stimulated by weak odors," says Ma. "It helps the brain make better sense out of odor responses when it integrates airflow information. We still don't know how it happens, but sniffing is essential for odor perception."
Karen Kreeger | EurekAlert!
Diagnoses: When Are Several Opinions Better Than One?
19.07.2016 | Max-Planck-Institut für Bildungsforschung
High in calories and low in nutrients when adolescents share pictures of food online
07.04.2016 | University of Gothenburg
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences