Selective facilitation of synapses in the neocortex by heterosynaptic activation.

Heterosynaptic facilitation (HF) of different excitatory postsynaptic potentials (EPSPs) can be recorded in the motor cortex os anesthetized cats following repetitively applied EPSP-spike stimulus pairs. HF turned out to be synapse-specific in many cases, because not all of the stimulated inputs in the same neuron could produce it. Furthermore, membrane depolarization, increase in membrane resistance and firing activity, can appear with or without HF of a test EPSP.