Morphological plasticity in neurons and competition for plasticity proteins

A hallmark of the brain is its ability to change functional connectivity in response to experience, providing - as it is presumed - the neurobiological basis for memory storage. Two recent studies from the Department of Cellular and Systems Neurobiology report on novel facets of the plasticity of synaptic connections. It was shown that the functional downregulation of synaptic connections, called long-term depression, is associated with the disappearance of tiny structural protrusions, named dendritic spines, which normally allow neurons to form excitatory synapses by attaching their presynaptic partners. By physically disrupting a synaptic connection, the loss of spines may thus could be one way of how a synaptic coupling between neurons becomes weakened in a long-lasting manner. In a second study it was demonstrated that synapses which were potentiated or strengthened at about the same time started to compete for the same set of proteins needed to maintain the elevated state of synaptic coupling: if the available pool of proteins is limited, additional strengthening of a subset of synapses leads to a weakening of previously potentiated synapses.