New York: In a study that could help advance drug development for Alzheimer's disease, researchers have found that a key aspect of human memory impaired in memory disorders exists in the type of pre-clinical animal models that influence major decisions about drug development.
The study, conducted in rats, showed for the first time that like humans the animals possess two independent "working memory" resources, or the ability to remember more information across two categories versus a single category.
In humans, working memory consists of two memory resources -- visual and auditory information. The average person, for example, cannot recall a phone number longer than seven characters despite easily remembering both the audio and video on a television show.
To test these forms of memory in animals, the researchers from Indiana University in the US challenged rats to memorise odours and spatial information.
To test rats' ability to remember spatial data, the scientists had them find food pellets inside a maze. To test their ability to remember new odours, they used pellets inside containers scented by up to 100 common household spices, with only new odours yielding food.
Across numerous trials, the scientists consistently showed that the rats could recall significantly more details in combination -- scents and spaces -- compared to trying to remember a single type of information.
"We saw high-level performance because the animals were encoding information in two dedicated memory resources," said one of the researchers Jonathon Crystal, professor at Indiana University Bloomington College of Arts and Sciences.
"This is the defining quality of working memory in people, and for the first time we have shown animals have this property of independent memory systems as well," Crystal noted.
The researchers believe that the findings published in the journal Current Biology could help scientists investigate complex forms of memory, which could help in the development of drugs to treat memory disorders.