Representation of Umami Taste in the Human Brain

Abstract

Umami taste stimuli, of which an exemplar is monosodium glutamate (MSG) and which capture what is described as the taste of protein, were shown using functional MRI (fMRI) to activate similar cortical regions of the human taste system to those activated by a prototypical taste stimulus, glucose. These taste regions included the insular/opercular cortex and the caudolateral orbitofrontal cortex. A part of the rostral anterior cingulate cortex (ACC) was also activated. When the nucleotide 0.005 M inosine 5'-monophosphate (IMP) was added to MSG (0.05 M), the blood oxygenation-level dependent (BOLD) signal in an anterior part of the orbitofrontal cortex showed supralinear additivity; this may reflect the subjective enhancement of umami taste that has been described when IMP is added to MSG. These results extend to humans previous studies in macaques showing that single neurons in these taste cortical areas can be tuned to umami stimuli.

Affective neuroscience of pleasure: reward in humans and animals

“…Neuroimaging evidence suggests the subjective enhancement correlates with activity in a lateral region of the midanterior orbitofrontal cortex (de Araujo et al 2003c). A similar type of response was also found in the mid-anterior part of the orbitofrontal cortex for the strong subjective enhancement of umami taste that occurs after adding a tiny ribonucleotide to umami (de Araujo et al 2003a).…”

“…On the right is shown the magnitude of the fitted hemodynamic response from a representative subject plotted against the subjective pleasantness ratings (on a scale from −2 to +2) and peristimulus time in seconds. b Additional evidence for the role of the mid-anterior orbitofrontal cortex in subjective experience comes from another neuroimaging experiment investigating the supra-additive effects of combining the umami tastants monosodium glutamate and inosine monophosphate (de Araujo et al 2003a). The figure shows the region of mid-anterior orbitofrontal cortex showing synergistic effects (rendered on the ventral surface of human cortical areas with the cerebellum removed).…”

A common neural scale for the subjective pleasantness of different primary rewards

“…We report results for brain regions where there were prior hypotheses on the basis of previous data. These regions have been previously shown to represent the reward value of taste, olfactory, flavor, somatosensory and temperature stimuli, and include the ventral prefrontal cortices, the pregenual cingulate cortex, and the ventral striatum (Craig et al, 2000;de Araujo et al, 2003a;de Araujo et al, 2003b;Kringelbach et al, 2003;McCabe and Rolls, 2007;Rolls and Grabenhorst, 2008;Rolls et al, 2003b). We applied small volume (false discovery rate) corrections for multiple comparisons for which p<0.05 (though the exact corrected probability values are provided) (Genovese et al, 2002) with a radius corresponding to the full width at half maximum of the spatial smoothing filter used.…”

Taste, olfactory and food texture reward processing in the brain and obesity

“…55 When the nucleotide 0.005 M inosine 5 0 -monophosphate (IMP) was added to MSG (0.05 M), the blood oxygenationlevel dependent signal in an anterior part of the OFC showed supralinear additivity, and this may reflect the subjective enhancement of umami taste that has been described when IMP is added to MSG. 16 (The supralinear additivity refers to a greater activation to the combined stimulus MSG þ IMP than to the sum of the activations to MSG Figure 2 A neuron in the primate OFC responding to the texture of fat in the mouth independently of viscosity.…”