The pleasure of eating: from receptors to the brain
A) The multisensory experience of food intake involves all the senses with different routes into the brain from receptors in the body, typically the eyes, ears, nose and oral cavity: From the distant processing of sight, sound and tactile of food to more proximal smell, taste and tactile (mouth-feel) processing. Smell is the most important determinant of the flavour of food and comes to the brain via orthonasal and retronasal pathways, experienced as we breathe in and out, respectively. B) Remarkably similar topology is found between people with vision (red) always processed in the back of the brain, audition (dark blue) processed in regions of the temporal cortex, touch (light blue) in somatosensory regions, and olfaction (orange) and taste (yellow) in frontal regions. Importantly, unlike the other senses, olfactory processing is not processed via the thalamus, which may explain the hedonic potency of odours. C) The pleasure system includes the orbitofrontal cortex (grey), the cingulate cortex (light blue), the ventral tegmental area in the brainstem (light red), the hypothalamus (yellow), the periventricular grey/periacqueductal grey (PVG/PAG, green), nucleus accumbens (light green), the ventral pallidum (light purple), the amygdala (light red) and the insular cortices (not shown).