SPACE TO THINK

The hippocampus is vital for memory, but researchers disagree on its exact role. Now, Dr Dharshan Kumaran and Senior Research Fellow Dr Eleanor Maguire have shown that it is active when people visualise navigating to different locations but not when they imagine networks of friends.

Dr Maguire has previously shown that taxi drivers have notably large hippocampi, presumably because of their need to carry about 'the knowledge' of London landmarks. But does the hippocampus store a 'virtual map' of the physical world or is it recalling relationships between objects in a more generic way?

To compare these theories, Dr Kumaran and Dr Maguire used functional magnetic resonance imaging to reveal which parts of participants' brains were active as they visualised the route between their friends' houses and then the social connections between the friends themselves.

The tasks activated separate brain networks, with the hippocampus involved only in spatial, not social, processing.

External links

• Kumaran D, Maguire EA. The human hippocampus: cognitive maps or relational memory? J Neurosci 2005;25(31):7254–9.