Storage of Long-Term Memories Depends on Protein Induction

Neuroscientists have identified a protein required for the establishment of new memories and their stabilization into the long-term memory.

Investigators from the University of Haifa (Haifa, Israel) used advanced genetic engineering techniques to create lines of mice lacking the protein PSD-95 in the "taste learning center” of the brain cortex. PSD-95 is a member of the membrane-associated guanylate kinase (MAGUK) family. It forms heteromultimers with another protein, DLG-2. With DLG-2, it is recruited into the same N-methyl d-aspartate (NMDA) receptor and potassium channel clusters. These two MAGUK proteins may interact at postsynaptic sites to form a multimeric scaffold for the clustering of receptors, ion channels, and associated signaling proteins.

Results published in the September 7, 2008, online issue of the journal Nature Neuroscience revealed that learning a new memory induced formation of PSD-95, but that recollection of familiar ones did not. Mice whose PSD-95 production was inhibited by genetic engineering lost the memories of new tastes a day after being introduced to them, while animals in the control group remembered the tastes. Thus, a new memory was created when PSD-95 was induced, but the information disappeared from the brain when the protein was not induced. Already existing taste memories were not lost by inhibition of PD-95.

Senior author Dr. Kobi Rosenblum, professor of neurobiology at the University of Haifa, explained, "The process of long-term memory creation in the human brain is one of the incredible processes which is so clearly different than ‘artificial brains' like those in a computer. While an artificial brain absorbs information and immediately saves it in its memory, the human brain continues to process information long after it is received, and the quality of memories depends on how the information is processed. One of the first processes to be affected in neurodegenerative diseases like Alzheimer's and Parkinson's is that of memory acquisition and processing. In this research, we identified one specific protein, among the many proteins active in brain synapses, whose production is essential for the brain to process and remember information it receives. The more we understand about the processes and elements involved in this complicated process, the sooner we will be able to develop medications which will delay the progression of cognitive degenerative diseases and enable patients to continue normative functioning.”

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