When faced with a new experience, such as choosing between unfamiliar food options, people think about relevant memories from past experiences to determine the consequences of their decision. These results, reported online this week in Nature Neuroscience, demonstrate how new associations may be formed to represent novel choices, even in the absence of direct experience.
In a functional magnetic resonance imaging (fMRI) study, Helen Barron, Timothy Behrens and colleagues first showed participants a cue associated with a familiar food (e.g. beetroot, custard, or avocado), which they had tasted before the experiment. Immediately after this first cue, the participants were shown another cue associated with a novel food (e.g., beetroot-flavoured custard), which they had not tasted before, but could potentially imagine its taste, by reactivating the experience of tasting beetroot or custard.
The authors take advantage of a phenomenon known as repetition suppression to find that their participants were indeed reactivating relevant past experiences when faced with the novel food. Repetition suppression happens when the same experience is reactivated again and again, and in response, the brain’s activity to that experience reduces over each repetition. As such, the authors found that the brain response to the cue associated with the novel food (beetroot custard) was reduced when it was preceded by a cue associated with one of the components (beetroot or custard) making up this novel food. This reduction was not there when the novel food was preceded by a cue associated with an unrelated food (e.g., avocado). Barron, Behrens, and colleagues suggest that this difference reflects repetition suppression, and therefore the same experience is being activated in the brain when the participants see a cue associated with a familiar food and a novel food, which includes this familiar component.