Have a tough time remembering where you put your keys, learning a new language or recalling names at a cocktail party? New research from the Lisman Laboratory at Brandeis University points to a molecule that is central to the process by which memories are stored in the brain. A paper published in the June 22 issue of the Journal of Neuroscience describes the new findings.
The brain is composed of neurons that communicate with each other through structures called synapses, the contact point between neurons. Synapses convey electrical signals from the "sender" neuron to the "receiver" neuron. Importantly, a synapse can vary in strength; a strong synapse has a large effect on its target cell, a weak synapse has little effect.
New research by John Lisman, professor of biology and the Zalman Abraham Kekst chair in neuroscience, helps explain how memories are stored at synapses. His work builds on previous studies showing that changes in the strength of these synapses are critical in the process of learning and memory.
"It is now quite clear that memory is encoded not by the change in the number of cells in the brain, but rather by changes in the strength of synapses," Lisman says. "You can actually now see that when learning occurs, some synapses become stronger and others become weaker."
But what is it that controls the strength of a synapse?
Lisman and others have previously shown that a particular molecule called Ca/calmodulin-dependent protein kinase II (CaMKII) is required for synapses to change their strength. Lisman's team is now showing that synaptic strength is controlled by the complex of CaMKII with another molecule called the NMDAR-type glutamate receptor (NMDAR). His lab has discovered that the amount of this molecular complex (called the CaMKII/NMDAR complex) actually determines how strong a synapse is, and, most likely, how well a memory is stored.
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