Cracking the spatial memory code

March 12, 2009

Researchers have shown that they can tell where a person is "standing" within a virtual reality room on the basis of the pattern of activity in the brain alone. The findings, published online on March 12th in Current Biology, a Cell Press publication, offer compelling evidence that the hippocampus, a region of the brain critical to navigation, memory, and imagining future experiences, works in a structured and predictable way. That discovery is contrary to what many experts had previously suspected, according to the researchers.

"You can predict where someone is standing by reading the patterns in their ," said Demis Hassabis of University College London. "You can track what is purely an internal thought."

"With this kind of research, we are approaching the realm of mindreading," added Eleanor Maguire, also of University College London.

In the new study, Hassabis, Maguire, and their colleagues asked four participants to navigate to target locations within a while their brains were scanned with a imager (fMRI). fMRI measures related to neural activity in the brain. They then applied a sophisticated analytical procedure known as multivariate pattern classification to see if they could relate the pattern of brain activity to each individual's location in virtual space.

And it worked. The pattern they uncovered reflected the participants' memory for where they were, the researchers explained, since once they had reached their final destination, there were no visual cues to discern one target spot from another. The activity they examined spanned some two to five million of the 40 million or so cells in the hippocampus, Hassabis noted.

Earlier studies done primarily in rats had suggested that stored in the hippocampus had neuronal representations that were uniform and randomly distributed. But if that were the whole story, the predictions made in the new study would not have been possible.

Now that they have shown that such a predictable functional structure exists in the hippocampus, additional studies will seek to crack that neural code for other memories. Indeed, spatial representations of the type investigated in the study are thought to form the scaffold upon which memories of our personal experiences, known as episodic memories, are built.

"By showing it is possible to detect and discriminate between memories of adjacent spatial positions, our combination of non-invasive in vivo high-resolution fMRI and multivariate analyses opens up a new avenue for exploring episodic memory at the population level," the researchers wrote. "In the future it may be feasible to decode individual episodic memory traces from the activity of neuronal ensembles in the human hippocampus."

"We know that the hippocampus is critical for remembering our life experiences," Maguire said. This discovery "opens a whole world of possibility previously thought inaccessible to human brain imaging."

Source: Cell Press (news : web)

Related Stories

Recommended for you

How even our brains get 'slacker' as we age

October 24, 2016

New research from Newcastle University, UK, in collaboration with the Federal University of Rio de Janeiro, investigated the way the human brain folds and how this 'cortical folding' changes with age.

How lying takes our brains down a 'slippery slope'

October 24, 2016

Telling small lies desensitises our brains to the associated negative emotions and may encourage us to tell bigger lies in future, reveals new UCL research funded by Wellcome and the Center for Advanced Hindsight.

Robotic tutors for primary school children

October 24, 2016

The use of robotic tutors in primary school classrooms is one step closer according to research recently published in the open access journal Frontiers in Computational Neuroscience.

Mouse decision-making more complex than once thought

October 24, 2016

Working with dot-counting mice running through a virtual-reality maze, scientists from Harvard Medical School have found that in order to navigate space rodent brains rely on a cascade of neural signals that culminate in ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.