fMRI measurement of the integrative effects of visual and chemical senses stimuli in humans

Abstract

The purpose of this study was to evaluate the integrative effects of visual stimuli with chemical senses (olfactory and gustatory) stimuli in humans. Noninvasive measurement tools such as magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) are used to describe the mechanism of olfactory information processing in the human brain, and the neurophysiological properties of olfactory-related neurons are described. The first study analyzed the interaction between visual and olfactory stimuli. Two odors (lemon and iso-valeric acid) were selected as pleasant and unpleasant odors, respectively and pleasant and unpleasant images were also selected. These cross-modal stimulus combinations were presented to the subject at random, and responses were measured by fMRI using an event related task. These results revealed that active brain areas with pleasant/unpleasant stimuli and matched/mismatched stimuli were different for memory and cognition. The second study analyzed the interaction between visual and gustatory stimuli. Total four conditions (hunger-not hunger, and intake-not intake of monosodium glutamate (MSG)) were tested. Visual stimuli were food-related and nonfood-related photos. A visual analog scale (VAS) was also used to evaluate before and at regular time intervals after intake of MSG, and responses were measured using fMRI. Brain activity related to feeding desire after intake of MSG occurred near the insula cortex, and orbito-frontal cortex, among other areas. These results on the integrative effects of visual stimuli with olfactory and gustatory stimuli, cross-modal and complex effects on olfaction and gustation were suggested to be obtained as an emotional response such as "pleasantness/unpleasantness" and as cognitive and memory responses such as "matching/mismatching" or the responses such as "feeding desire" afterwards intake of foods.

Emotional pictures and sounds: a review of multimodal interactions of emotion cues in multiple domains

“…To make research more ecological valid and to evolve a broader and more complete concept of emotional multimodality, future research should not only concentrate on audiovisual emotion processing but should also incorporate cues from other sensory channels as, e.g., olfactory ( Pause, 2012 ; Adolph et al, 2013 ), somatosensory ( Francis et al, 1999 ; Gerdes et al, 2012 ; Wieser et al, 2012a , 2014 ), or gustatory signals ( O’Doherty et al, 2001 ; Tonoike et al, 2013 ) which are also known to elicit emotional reactions and may interact with information processes of other modalities.…”

MEG as a Medical Diagnostic Tool in the Greek Population

“…Matching an ECD model to the extracranial magnetic field became a simple and convenient method for localizing sources of cerebral activity. Experimental studies proved the accuracy of ECD localization of sources of interictal discharges (38)(39)(40)(41)(42)(43)(44).…”

Simultaneous Smelling an Incense Outdoor and Putting the Hands Together Activate Specific Brain Areas

“…Neurophysiological experiments in monkeys have shown that the olfactory nervous center and olfactory pathway project to the orbitofrontal cortex [55][56][57]. In humans, olfactory event-related potentials and magnetic fields evoked by odorant pulses synchronized with respiration are also found in the orbitofrontal area [5,6,58,59].…”