Brain scan of the hippocampus

Scientists at Baycrest’s Rotman Research Institute have uncovered an important clue in the brain’s hippocampus that may help solve a longstanding neuroscience mystery about differences in memory ability between people.

A growing body of research has already shown that, among healthy young adults, the overall size of the seahorse-shaped memory centre does not predict an individual’s ability in recollection memory, but other aspects of its anatomy may provide a clue.

According to this latest study, featured in the December 22nd issue of Neuron, stronger recollection memory is predicted by a larger posterior region of the hippocampus when compared to the anterior region. The greater the size imbalance between a larger posterior region and smaller anterior region, the more likely an individual will have stronger recollection memory.

“Our results show for that the size of the posterior hippocampus, especially when expressed as a ratio to the size of the anterior hippocampus, reliably predicts recollection in healthy adults,” said Dr. Jordan Poppenk, who led the study at Baycrest as a graduate student in Psychology, with senior author and cognitive scientist Dr. Morris Moscovitch.

The researchers also found evidence that the functional connections, possibly related to memory consolidation, between the posterior hippocampus and other parts of the brain may underlie enhanced memory collection.

The study began with high-resolution brain scanning of 18 healthy young adults to collect anatomical MRI (magnetic resonance imaging) and functional MRI data, and taking measurements of hippocampal volume and connectivity. Participants completed a test to measure their recollection memory ability. Better recollection was associated with a larger posterior hippocampus and a smaller anterior hippocampus.

This same overall pattern was found again in three separate studies conducted by other Rotman scientists and analyzed by the researchers – that involved 38 additional participants.