Fig. 4. Various patterns of excitatory postsynaptic currents (EPSCs) elicited by focal stimulation at a frequency of 10 Hz. Monosynaptic evoked EPSCs (A ). Both the monosynaptic- and polysynaptic-evoked EPSCs (B ). Polysynaptic evoked EPSCs (C ). These evoked EPSCs were observed in different neurons. HP = holding potential.