Fig. 4.

Hedonic experience. a The activity in mid-anterior parts of the orbitofrontal cortex correlated with the subjective pleasantness ratings of the foods (Kringelbach et al. 2003). 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). The synergy is unlikely to be expressed in the taste receptors themselves, and the activity in the orbitofrontal cortex may thus reflect the subjective enhancement of umami taste, which must be closely linked to subjective experience. c Adding strawberry odor to a sucrose taste solution makes the combination more pleasant than the sum of each of the individual components. The supra-linear effects on subjective enhancement activated a lateral region of the left mid-anterior orbitofrontal cortex, similar to as found in other experiments (de Araujo et al. 2003c). d These findings were strengthened by findings using DBS and MEG (Kringelbach et al. 2007a). Pleasurable subjective pain relief for chronic pain in a phantom limb in a patient was causally induced by effective deep brain stimulation in the PVG/PAG part of the brainstem. When using MEG to directly measure the concomitant changes in the rest of the brain, a significant change in power was found in the mid-anterior OFC