At the cortical level, the anterior insular cortex, lateral orbital frontal cortex and anterior cingulate cortex, all have well established roles in signalling stimulus value across contexts, including appetitive choices, and in integrating food features that govern preferences (for example, the odour and flavour of food)5,6.
Rothschild also gave examples of odours which themselves are clearly noxious.
Flies, for example, avoid an odour once it has been associated with the onset of an electric shock (odour → shock; henceforth called punishment-learning); yet they approach an odour once it has been associated with shock offset (shock → odour; henceforth called relief-learning; [ 2, 3]).
For example, the characteristic odour (to humans) of plants in the cabbage family is produced by sulfur-containing compounds called isothiocyanates.
Despite this numerical simplicity of their brains, the behaviour of Drosophila larvae is not hard-wired (Gerber and Stocker, 2007; Diegelmann et al., 2013; Schleyer et al., 2013): for example, presenting an odour with a food reward establishes associative memory that is specific for the kind and the intensity of the trained odour.
Another striking example is the odour-sensing organ of the silk moth, Bombyx mori.
In context A, odour 2 (for example, cinnamon) was now rewarded and in context B odour 1 (for example, coffee) was rewarded.
Some well-water supplies, for example, have a rotten-egg odour that is caused by hydrogen sulfide gas.
For example, one form of an odour molecule called limonene smells of lemons, the other of oranges.
For example, female house mice show odour preferences for outbred over inbred males, though only inbred females show this preference [ 43].
