Despite brain damage, working memory functions -- within limits

October 12, 2010

Researchers at the University of California, San Diego School of Medicine, led by Larry R. Squire, PhD, professor of psychiatry, psychology and neurosciences at UC San Diego and a scientist at the VA San Diego Healthcare System, report that working memory of relational information - where an object is located, for example - remains intact even if key brain structures like the hippocampus are damaged.

The findings, published in the October 13, 2010 issue of The Journal of Neuroscience, run contrary to previous research that suggested spatial information, especially if it's linked to other kinds of information, necessarily involves the hippocampus and other regions associated with memory.

Working memory is the mental ability to hold small amounts of information in an active, readily available state for a short period of time, typically a few seconds. Conversely, long-term memory involves storing a potentially unlimited amount of information for an indefinite period of time.

Squire and colleagues examined four memory-impaired patients with damage to their medial temporal lobes (MTL), a region of the cerebral cortex containing the hippocampus and linked to long-term memory formation.

The four patients were asked to briefly study an arrangement of objects on a table, then reproduce the objects' relative positions on another table. When the number of objects was three or less, the patients' ability to recall was similar to that of control subjects without brain damage. The impaired patients easily remembered where the objects had been placed in relation to each other.

But "their performance abruptly collapsed when the limit of working memory was reached," said Squire. The patients could not remember the locations of four or more objects because doing so involved tapping into long-term memory functions in the medial temporal lobe.

"The findings provide strong evidence for a fundamental distinction in the brain between working memory and long-term memory, even in the realm of spatial information and spatial-object associations," Squire said.

The work has practical and clinical significance as well, according to Squire.

"It indicates that patients with memory impairment due to MTL damage, including early stage Alzheimer's disease, have a narrower difficulty than what one might have thought. They have an intact ability to hold information in mind, and an ability to work with it on a temporary basis."
-end-
Co-authors of the paper are Annette Jeneson of the UCSD Department of Psychology, and Kristin N. Mauldin of the UCSD Department of Psychiatry.

University of California - San Diego

Related Memory Articles from Brightsurf:

Memory of the Venus flytrap
In a study to be published in Nature Plants, a graduate student Mr.

Memory protein
When UC Santa Barbara materials scientist Omar Saleh and graduate student Ian Morgan sought to understand the mechanical behaviors of disordered proteins in the lab, they expected that after being stretched, one particular model protein would snap back instantaneously, like a rubber band.

Previously claimed memory boosting font 'Sans Forgetica' does not actually boost memory
It was previously claimed that the font Sans Forgetica could enhance people's memory for information, however researchers from the University of Warwick and the University of Waikato, New Zealand, have found after carrying out numerous experiments that the font does not enhance memory.

Memory boost with just one look
HRL Laboratories, LLC, researchers have published results showing that targeted transcranial electrical stimulation during slow-wave sleep can improve metamemories of specific episodes by 20% after only one viewing of the episode, compared to controls.

VR is not suited to visual memory?!
Toyohashi university of technology researcher and a research team at Tokyo Denki University have found that virtual reality (VR) may interfere with visual memory.

The genetic signature of memory
Despite their importance in memory, the human cortex and subcortex display a distinct collection of 'gene signatures.' The work recently published in eNeuro increases our understanding of how the brain creates memories and identifies potential genes for further investigation.

How long does memory last? For shape memory alloys, the longer the better
Scientists captured live action details of the phase transitions of shape memory alloys, giving them a better idea how to improve their properties for applications.

A NEAT discovery about memory
UAB researchers say over expression of NEAT1, an noncoding RNA, appears to diminish the ability of older brains to form memories.

Molecular memory can be used to increase the memory capacity of hard disks
Researchers at the University of Jyväskylä have taken part in an international British-Finnish-Chinese collaboration where the first molecule capable of remembering the direction of a magnetic above liquid nitrogen temperatures has been prepared and characterized.

Memory transferred between snails
Memories can be transferred between organisms by extracting ribonucleic acid (RNA) from a trained animal and injecting it into an untrained animal, as demonstrated in a study of sea snails published in eNeuro.

Read More: Memory News and Memory Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.