A new look at how memory and spatial cognition are related

August 4, 2008

In a study that sheds new light on how memory and spatial cognition are related to each other in the brain, researchers at the University of California, San Diego School of Medicine and the Veteran Affairs (VA) San Diego Healthcare System studied memory-impaired patients as they navigated their environment.

Path integration, or the ability of the brain to compute the distance and direction of a traveled path, is an important aspect of spatial cognition – an ability long-thought to be dependent on the medial temporal lobe structures of the brain.

However, the researchers discovered that the hippocampus and entorhinal cortex – two major medial temporal lobe structures – are not essential for path integration. Their findings will be published in the early on line edition of Proceedings of the National Academy of Sciences (PNAS) the week of August 4.

The study, led by Larry R. Squire, Ph.D., professor of psychiatry, neurosciences and psychology at UCSD School of Medicine and research career scientist at the VA San Diego Healthcare System, was designed to measure whether these structures of the brain are essential for spatial cognition.

"For decades, the medial temporal lobe structures have been linked to both memory and spatial cognition," said Squire. One important aspect of spatial cognition is keeping track of a reference location during movement by using internal cues, Squire explained, yet such tracking also relies on memory. "So we set out to test how these two abilities related to one another and to the temporal lobe area of the brain."

The researchers looked at five memory-impaired patients with lesions of the medial temporal lobe along with seven matched controls, testing each for their path integration ability. Participants, who were blindfolded and wore noise-canceling earphones, were led by researchers on 16 paths and asked to keep their starting point in mind. After walking the path, participants were asked to point to their start location.

Due to their lesions, the five patients all had long-term memory impairment, so the paths were short enough that the task could be performed within the span of their working, or short-term, memory. Building on the idea that working memory is independent of the medial temporal lobe, the researchers theorized that these patients should succeed at the task if performed within the span of their short-term memory, unless this section of the brain was also necessary for spatial cognition.

The memory-impaired patients pointed to and estimated their distance from the start location as accurately as the controls.

"We concluded that the hippocampus and entorhinal cortex are not essential for path integration, since we showed that the tests could be successfully accomplished despite damage to these brain regions," said Squire.

Source: University of California - San Diego

Explore further: 4-D technology allows self-folding of complex objects

Related Stories

4-D technology allows self-folding of complex objects

September 21, 2015

Using components made from smart shape-memory materials with slightly different responses to heat, researchers have demonstrated a four-dimensional printing technology that allowed creation of complex self-folding structures.

The early detection of age-related memory deficits in mice

March 29, 2010

By studying the aging of memory in the mouse, CNRS researchers (France) have developed an experimental protocol that can detect age-related memory deficits at an early stage. They have shown that even at 10 months, which ...

Recommended for you

How the finch changes its tune

August 3, 2015

Like top musicians, songbirds train from a young age to weed out errors and trim variability from their songs, ultimately becoming consistent and reliable performers. But as with human musicians, even the best are not machines. ...

Machine Translates Thoughts into Speech in Real Time

December 21, 2009

(PhysOrg.com) -- By implanting an electrode into the brain of a person with locked-in syndrome, scientists have demonstrated how to wirelessly transmit neural signals to a speech synthesizer. The "thought-to-speech" process ...


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.