Novelty and the Brain

December 2006 - New research published in the journal Public Library of Science Biology identifies a possible mechanism for how the brain allows us to anticipate future events and detect unexpected outcomes Dr Dharshan Kumaran and Dr Eleanor Maguire at the Wellcome Trust Centre for Neuroimaging at University College London have shown that the hippocampus, part of the brain believed to play a crucial role in learning and memory, predicts what will happen next by automatically recalling a sequence of events in response to a single cue.

The researchers used an fMRI scanner, which monitors changes in blood flow within the brain to measure brain activity, to show how the brain reacts to unexpected changes in a sequence of images. Subjects are shown a series of four images which are then repeated, changing the order of the final two. The hippocampus appeared to react when a different image appeared.

Dr Kumaran said:

"These experiments indicate that the hippocampus acts as a sort of comparison device, matching up past and present experience. It does not appear to be reacting to novelty as such, but rather to discrepancies between what it expects to see and what it actually sees."

The researchers suggest that when prompted by a cue, the hippocampus recalls a sequence of associated memories. This may explain how recollection of an entire past experience can be triggered by seeing a particular face or listening to a piece of music. The hippocampus appears to perform a critical comparison between past and present experiences alerting us to unexpected changes.

Dr Kumaran continued:

"Patients with damaged hippocampi, such as those with Alzheimer's Disease, often have trouble remembering sequences of events or finding their way around. This would seem to be because the damaged hippocampus is unable to rapidly bind together the many different components of our experiences into a coherent whole."