The olfactory system

There are 1000 gene-specified olfactory receptor types projecting to the olfactory bulb and then to the olfactory (pyriform) cortex. This processing enables what the odour is to be represented. The olfactory (pyriform) cortex then projects to the orbitofrontal cortex, where the representation is mapped away from a gene-specified space into an odour reward value space, with the orbitofrontal cortex responding for example to the pleasantness of odours including the smell and flavour of food. The mechanism of the transform includes pattern association with stimuli in other modalities, such as the taste and texture of food.