This process is called long-term potentiation or LTP. When LTP occurs in the hippocampi, two curved regions that flank the center of the brain, changes occur in synapses. These connections between neurons the major site for information exchange in the brain become stronger after repeated stimulation. This increased synaptic strength can last hours, even days, and is believed to be the cellular basis for memory.
AMPA receptors on the membrane of the information-receiving neuron, known as the postsynaptic cell, act like gates, opening in response to chemical messages from a neighboring neuron. During LTP, extra AMPA receptors appear, increasing synaptic strength. But where do these extra receptors come from?
Michael Ehlers, associate professor of neurobiology at Duke, believed that recycling endosomes, or membrane-bound compartments inside neurons, carry a reserve pool of these receptors. To test his theory, Ehlers called on Julie Kauer at Brown.
Kauer, associate professor medical science in the Department of Molecular Pharmacology, Physiology and Biotechnology, proved that Ehlers' theory was correct. By injecting mutant proteins marked with green fluorescent dye into the hippocampal neurons of rats, Kauer and her laboratory team found that AMPA receptors are indeed stored in recycling endosomes. When the neuron is stimulated, AMPA receptors leave this compartment and are rushed down the dendritic spine by three "chaperone" proteins Rab11a, Rme1, and Syn13. These additional receptors are then inserted into the plasma membrane, boosting reception of memory-making infor
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Contact: Wendy Lawton
Wendy_Lawton@brown.edu
401-863-1862
Brown University
23-Sep-2004