The aim of this chapter is to describe how fat in the mouth is represented in the brain. This is an important issue, for it is not yet clear how oral fat is sensed, and evidence from neuroscience is providing indications about this. Moreover, fat in the diet may be pleasant, yet its intake must be controlled, and understanding the rules by which the pleasantness of fat is regulated is important. In addition, the brain’s representation of oral fat is frequently in terms of particular combinations with other sensory aspects of food, including taste, texture, and olfactory inputs, and these combinations are important for understanding the full impact of fat in the mouth on the pleasantness of food.
Because the representation of fat in the mouth is closely linked to taste processing in the brain, we start with an overview of taste pathways and processing in the brain, before we consider how oral fat is represented in the same brain areas, and frequently but not always in combination with taste. To make the results relevant to understanding the control of human food intake, complementary evidence is provided by neurophysiological studies in nonhuman primates in which the taste and related pathways are similar to those in humans, and by functional neuroimaging studies in humans. A broad perspective on brain processing involved in hedonic aspects of the control of food intake and in affective responses more generally is provided by Rolls (2005).
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