Wednesday, March 02, 2005

Picking Up a Scent
I received a Page-A-Day Calendar for Christmas. Mine was the Wine Lover's . You also get a free on-line calendar so I've added it the Blog. Look to your right-> Probably breaking some sort of Copyright doing so but if it helps you know what day it is and you learn a bit of wine lore then maybe you'll get your own. The note for yesterday was about odors. One of my favorite subjects. That got me doing literature searches again to see if there is anything new on odor perception. I won't bore you with the details, just the summary of one which led me to another.

Color has a profound effect on the perception of odors. For example, strawberry flavored drinks smell more pleasant when colored red than green and descriptions of the 'nose' of a wine are dramatically influenced by its color. Using functional magnetic resonance imaging (fMRI) we demonstrate a neurophysiological correlate of these crossmodal visual influences on olfactory perception. Subjects were scanned while exposed either to odors or colors in isolation, or to color-odor combinations that were rated on the basis of how well they were perceived to match. Activity in caudal regions of the orbitofrontal cortex and in the insular cortex increased progressively with the perceived congruency of the odor-color pairs. These findings demonstrate the neuronal correlates of olfactory response modulation by color cues in brain areas previously identified as encoding the hedonic value of smells. The color of scents:chromatic stimuli modulate odor responses in the human brain. Osterbauer RA, Matthews PM, Jenkinson M, Beckmann CF, Hansen PC, Calvert GA. J Neurophysiol. 2005 Feb 2; [Epub ahead of print].

Human olfactory perception is notoriously unreliable, but shows substantial benefits from visual cues, suggesting important crossmodal integration between these primary sensory modalities. We used event-related fMRI to determine the underlying neural mechanisms of olfactory-visual integration in the human brain. Subjects participated in an olfactory detection task, whereby odors and pictures were delivered separately or together. By manipulating the degree of semantic correspondence between odor-picture pairs, we show a perceptual olfactory facilitation for semantically congruent (versus incongruent) trials. This behavioral advantage was associated with enhanced neural activity in anterior hippocampus and rostromedial orbitofrontal cortex. We suggest these findings can be interpreted as indicating that human hippocampus mediates reactivation of crossmodal semantic associations, even in the absence of explicit memory processing. The nose smells what the eye sees: crossmodal visual facilitation of human olfactory perception. Gottfried JA, Dolan RJ. Neuron. 2003 Jul 17;39(2):375-86.

All because of this little study. Well not entirely, but it certainly influenced both.

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