Bi-directional Changes In Dendritic Spatial Summation Accompanying Long-term Synaptic Modifications

Information processing in the neuron requires spatial summation of synaptic inputs at the dendrite. In CA1 pyramidal neurons of the hippocampus, a brief period of correlated pre- and postsynaptic activity, which induces long-term potentiation (LTP) or long-term depression (LTD), results in a persistent increase or decrease in the linearity of spatial summation, respectively. Such bi-directional modification of the summation property is specific to the modified input and reflects localized dendritic changes involving Ih channels and NMDA receptors. Thus, correlated pre- and postsynaptic activity alters not only the strength of the activated input, but also its dendritic integration with other inputs.