WEDNESDAY, June 9, 2004 (HealthDayNews) -- Storage of long-term memories is dependant on the size and shape of synapses among neurons in the outer part of the brain called the cerebral cortex, says a study in the June 10 issue of Neuron.
This finding by neuroscientists at the Picower Center for Learning and Memory at the Massachusetts Institute of Technology (MIT) is the first to make this connection.
The researchers created mutant mice with abnormally structured synapses in the cortex but with normal synapses in the hippocampus, the area of the brain that turns information into memory. The mice were made to swim around a water maze, using visual clues to find their way to a hidden dry platform.
The mutant mice could learn the location of the platform, but couldn't remember where it was when they repeated the task a few weeks later. Normal mice had no problem remembering the location of the platform.
This showed that, while their short-term memory was fine, the mutant mice had impaired long-term memory storage.
The researchers say their study confirms what's long been suspected -- that specific physical structures in the brain act as repositories for memory, knowledge and experience.
The finding may also help scientists better understand cognitive dysfunction and memory deficits in people who are mentally retarded. A number of the genes linked to mental retardation regulate the formation of synapses.
The Nemours Foundation has more about memory.