NEW YORK (Reuters Health) - For the first time, scientists have identified a protein in the brain that is required for turning short-term memories into permanent ones.
Initial learning takes place in one part of the brain, the hippocampus, but these first experiences become permanent memories only after reinforcement in the brain's outermost layer, the cortex, according to Dr. Alcino J. Silva from the University of California at Los Angeles and associates.
Until now, little was known about the processes involved in making that translation.
The authors tested mice that had only half the normal levels of a protein called alpha-CaMKII. The total absence of this protein results in learning and memory problems. The model they used enabled the scientists to separate the short-term learning functions of the hippocampus from the permanent memory functions of the cortex.
Mice with less alpha-CaMKII learned tasks as well as normal mice, the authors report in the May 17th issue of Nature, but--unlike normal mice--they forgot the tasks within a few days. The timing of this memory loss, they say, matches the shift in the memory function from the hippocampus to the cortex.
Using sophisticated measurements of the electrical activity of the brain, the researchers also showed that mice deficient in alpha-CaMKII have disruptions in the type of activity usually associated with the development of memories. Again, these disruptions were present in the cortex, but not in the hippocampus.
``We have uncovered new insights into the function of this protein (it is involved in the formation of permanent memories in the cortex), but our work also speaks to the sites and mechanisms required to establish permanent memories in the brain,'' Silva told Reuters Health. ``This information will be essential to design therapies to memory disorders.''
``Our article reports the first molecular and cellular information into one of memory's most mysterious processes: how we establish the memories that the brain retains, the ones that become our oldest memories,'' Silva concluded. ``These are very specific (and hopefully important) clues into this mysterious and wonderful process.''
