Figure 4

Motivation-independent representations of food in primary sensory cortices. Pure taste is the archetypical reinforcer associated with food. A) Consistent with findings in non-human primates, neuroimaging has located the primary human taste cortex in bilateral anterior insular/frontal opercular cortices (yellow circles) with peak MNI coordinates of [x, y, z: 38,20,–4] and [x, y, z: −32,22,0] [53]. B) This data is based on 40 datasets from four experiments using eight unimodal and six multimodal taste stimuli ranging from pleasant to unpleasant. Each small aliquot of 0.75 mL taste stimulus was delivered via polythene tubes to the mouth of the participant who was asked to move it around before being cued to swallow after typically 10 s. To properly control and rinse out the effects of each stimulus, the taste stimulus was followed by a tasteless solution with the main ionic components of saliva. The time course of blood oxygen-level detection (BOLD) activity in right primary taste cortex is shown for all 40 subjects (top) and averaged across all (bottom) (for taste minus tasteless solution). C) Multisensory sensory integration was found in a region of the anterior insular cortex which responded to pure taste, orthonasal smell and flavour (retronasal smell and taste) [63].