Researchers Find That Sense Of Smell Is Dependent On Body Position

This research, conducted in the laboratory of Dr. Marilyn Jones-Gotman at the MNI, adds to previous studies indicating that lying down negatively affects other senses, such as hearing and spatial perception. "This was an important finding for us, as many of our studies involve test subjects lying in an imaging machine such as MRI or PET (positron emission tomography) scanners. If perceptual ratings differ depending on whether the subject is outside a scanner (and sitting up) or inside a scanner (and lying down), then reliable 'threshold measures' or points of comparison will be difficult to obtain."

Test subjects were exposed to 16 different concentrations of rose odour while they were sitting upright or lying down. The majority (63.9%) of participants were found to have a decreased sensitivity to the rose odour when lying down.

"There is a clear difference in olfactory sensitivity depending on the body position of the subjects," explained Dr. Johan Lundstrom, a postdoctoral fellow with Dr. Jones-Gotman. "Right now, we can only speculate as to the biological necessity of this difference. For example, is a lowered sensitivity to smell when lying down part of an overall sleep preparedness mechanism? Or perhaps the reason is only secondary to an increase of body fluid circulating throughout the brain? It could also be that we are simply not able to 'sniff' as deeply when in a supine position. Whatever the reason, we must now take this difference into account when planning future studies."

This research was supported by the Canadian Institutes of Health Research and the Swedish Foundation for International Cooperation in Research and Higher Education.

The Canadian Institutes of Health Research (CIHR) (www.cihr-irsc.gc.ca) is the Government of Canada's agency for health research. CIHR's mission is to create new scientific knowledge and to catalyze its translation into improved health, more effective health services and products, and a strengthened Canadian health care system. Composed of 13 institutes, CIHR provides leadership and support to close to 10,000 health researchers and trainees across Canada.

The Montreal Neurological Institute (www.mni.mcgill.ca) is a McGill University (www.mcgill.ca) research and teaching institute, dedicated to the study of the nervous system and neurological diseases. Founded in 1934 by the renowned Dr. Wilder Penfield, the MNI is one of the world's largest institutes of its kind. MNI researchers are world leaders in cellular and molecular neuroscience, brain imaging, cognitive neuroscience and the study and treatment of epilepsy, multiple sclerosis and neuromuscular disorders. The MNI, with its clinical partner, the Montreal Neurological Hospital (MNH), part of the McGill University Health Centre (www.muhc.ca), continues to integrate research, patient care and training, and is recognized as one of the premier neuroscience centres in the world. Already well known for its McConnell Brain Imaging Centre, the MNI will expand its brain imaging research in the next several years through a $28-million award from the Canada Foundation for Innovation, made in partnership with the government of Quebec. There will also be further development of MNI initiatives in multiple sclerosis, optical imaging and nano-neuroscience.