Flavor processing: More or less than the sum of its parts?
Single Paper Presentation
Northwestern University Feinberg Medical School
Abstract ID Number: 62
Last modified: May 20, 2003
Multimodal sensory integration is fundamental to the chemical senses. We often hear without seeing and see without hearing but only when we have a cold do we taste without smelling. The neurophysiology of taste parallels perceptual experience. Only a small percentage of cells in the so-called primary and secondary taste cortices respond to taste. Within these heteromodal regions there is overlapping representation of taste, smell, oral somatosensation, hunger and more. Neuroimaging studies in humans show that odors and tastes are equally effective in activating overlapping regions of the insular primary gustatory region, orbitofrontal cortex secondary taste regions, anterior cingulate cortex and amygdala. This organization is markedly different from the visual, somatosensory and auditory systems.
Data from functional imaging studies will be presented suggesting that 1) the amygdala, insula, orbitofrontal cortex and anterior cingulate cortex form a network for flavor processing with the orbitofrontal cortex at the epicenter, 2) the flavor network is preferentially activated by previously experienced taste/smell pairs, and 3) that the mode of olfactory stimulation (orthonasal vs retronasal) may have a profound effect upon taste/smell integration. These data suggest that the neural substrates of flavor are formed via association learning of temporally and spatially co-occurring tastes and smells.