Researchers have a new explanation for one of the brain’s most uncanny peculiarities – the phenomenon of déjà vu. Presenting his team’s latest work at the recent International Conference on Memory in Budapest, Akira O’Connor from the University of St Andrews described how apparent glitches in the Matrix may in fact just be the brain fact-checking its own memory system.
According to New Scientist, O’Connor and his colleagues began by devising a technique to artificially trigger déjà vu. To achieve this, they presented study participants with a series of connected words, without revealing the one word that links them. For instance, in one trial the words bed, pillow, dream and night were all presented, yet the term sleep – which clearly connects all of these words – was omitted.
To make sure participants registered that they hadn’t heard the word sleep, the researchers asked them whether or not they had heard any words beginning with an "S", to which they obviously replied in the negative. However, when they were later grilled on which words had been presented, most tended to think they could remember hearing the word sleep, despite knowing that they hadn’t, resulting in an eerie sense of déjà vu.
Using functional magnetic resonance imaging (fMRI), the team observed that when this occurred, the most active regions of participants’ brains were not those normally associated with memory, such as the hippocampus. Instead, the frontal areas, which are typically involved in decision making, were activated during the déjà vu experience.
As such, O’Connor believes that these frontal regions probably monitor our memories as they are replayed, looking for errors in their content and becoming activated when they spot an irregularity. As Stefan Köhler from the University of Western Ontario told New Scientist: “There may be some conflict resolution going on in the brain during déjà vu.”
Though more work is needed in order to validate this theory, if correct it would suggest that the brain engages in quality control, monitoring its own activities and flagging up any errors that might occur. In this context, the frontal areas seem to be checking for inconsistencies between what we remember happening and what we know happened.
[H/T: New Scientist]