PROPAGATION OF ACTIVITY-DEPENDENT SYNAPTIC DEPRESSION IN SIMPLE NEURAL NETWORKS

Triple whole-cell recordings from simple networks of cultured hippocam pal neurons show that induction of long-term depression at glutamaterg ic synapses is accompanied by a back propagation of depression to inpu t synapses on the dendrite of the presynaptic neuron. The depression a lso propagates laterally to divergent outputs of the presynaptic neuro n and to convergent inputs on the postsynaptic neuron. There is no for ward propagation of depression to the output of the postsynaptic neuro n and no presynaptic propagation accompanying long-term depression at GABAergic synapses. Activity-induced synaptic modification is therefor e not restricted to the activated synapse, but selectively propagates throughout the neural network.