We don't always perceive things the way they are. People's expectations of a taste modify activity in the primary taste areas of the brain, reports a study in the March issue of Nature Neuroscience.
Jack Nitschke and colleagues studied how expectancy influences the way we perceive a taste by monitoring the brain activity of subjects presented with different tastes. During brain scanning, subjects tasted an unpleasant bitter or a pleasant sweet taste, and then indicated how aversive they found the taste. Before each tasting, they saw a cue that signaled whether the taste would be pleasant or unpleasant. Occasionally, these cues were misleading, and a very unpleasant taste was preceded by a cue indicating only a mildly unpleasant taste. Subjects rated the unpleasant taste as less aversive when it was preceded by this misleading cue, and this perception was accompanied by less activation in the primary taste cortex. When the same taste was preceded by the correct cue, indicating it would be very unpleasant, subjects found it more aversive, and there was greater activation in the primary taste cortex.
These results indicate that contrary to previous research, the primary taste cortex does not respond solely to inputs from taste buds, and that expectancy modulates our perception of events.
Jack Nitschke (University of Wisconsin, WI, USA)
Abstract available online.
(C) Nature Neuroscience press release.
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