Where life's memories are stored

Jun 01, 2005

By studying in detail the ability of patients with selective brain damage to recall events in their past, researchers, led by Larry R. Squire of the University of California San Diego and Veterans Affairs Medical Center, have helped settle a long-standing controversy about where the long-term memory of one's personal experiences are stored. The research is published in the June 2 issue of Neuron.

The controversy has revolved around whether long-term memory continues to depend on the region called the medial temporal lobe, which contains the brain's memory-processing center, the hippocampus. According to this view, such "autobiographical" memories depend on specific contextual information that would require the continued involvement of the brain's central memory structures.

The other view is that autobiographical memories, like other types of shorter-term memories, gradually become independent of the medial temporal lobe as time passes.

Memory studies of brain-damaged patients have not yielded a clear winner, because of the complexity of such damage and the difficulty in accurately documenting the quality of such memories.

Now, Squire and his colleagues have presented evidence that "the ability to recollect remote autobiographical events depends not on the medial temporal lobe but on widely distributed neocortical areas."

In their experiments, Squire and his colleagues studied patients with damage limited to the medial temporal lobe as well as those with broader damage to the neocortex. The damage was due to such problems as ischemia due to drug overdose, brain aneurysm, or encephalitis.

They triggered patients' long-term memories by presenting them with "cue" words such as "river," "bottle," and "nail." The scientists asked the patients to recall events in their lives associated with those words. They then asked the patients to rate the quality of those memories. Specifically, they asked the patients to distinguish "remembering" the event versus "knowing" the event. "Remembering" meant that the patients could place themselves in the event, while "knowing" meant that they knew it happened to them, but could not "travel back in time" to reexperience the event. The researchers also asked the patients to score the vividness of the recalled imagery and whether they recalled the event from the first-person perspective. They compared the performance of the patients to that of a normal control group.

"There were two major findings," reported the researchers. "First, the patients with damage restricted mainly to the medial temporal lobe performed normally on tests of remote autobiographical memory, whereas the patients with significant damage to the neocortex were severely impaired.

"Second, by three measures…the subjective experience of remote autobiographical recollection was normal in the five patients with damage restricted mainly to the medial temporal lobe.

Publication: Bayley, P.J., Gold, J.J., Hopkins, R.O. and Squire, L.R. (2005) The Neuroanatomy of Remote Memory. DOI 10.1016/j.neuron.2005.04.034 Publishing in Neuron, Vol. 46, pages 799–810, June 2, 2005. www.neuron.org

Explore further: Earlier Stone Age artifacts found in Northern Cape of South Africa

add to favorites email to friend print save as pdf

Related Stories

Engineering light-controlled proteins

Jul 03, 2014

(Phys.org) —A University of Wyoming professor has engineered proteins that can be activated by near-infrared light as a way to control biological activities in deep tissues of small mammals.

Radioactive nanoparticles target cancer cells

May 21, 2013

Cancers of all types become most deadly when they metastasize and spread tumors throughout the body. Once cancer has reached this stage, it becomes very difficult for doctors to locate and treat the numerous tumors that can ...

Recommended for you

Affirmative action elicits bias in pro-equality Caucasians

1 hour ago

New research from Simon Fraser University's Beedie School of Business indicates that bias towards the effects of affirmative action exists in not only people opposed to it, but also in those who strongly endorse equality.

Narcissistic CEOs and financial performance

20 hours ago

Narcissism, considered by some as the "dark side of the executive personality," may actually be a good thing when it comes to certain financial measures, with companies led by narcissistic CEOs outperforming those helmed ...

Election surprises tend to erode trust in government

20 hours ago

When asked who is going to win an election, people tend to predict their own candidate will come out on top. When that doesn't happen, according to a new study from the University of Georgia, these "surprised losers" often ...

User comments : 0