Figure 3.

(A) Intrinsic firing patterns of a regular-spiking layer VI neuron (Upper) and a synaptically coupled VP neuron (Lower) revealed by injection of current. (B Upper) Averaged trace of single action potentials induced by injection of current into the layer VI neuron. (B Lower) Average of unitary EPSP successes recorded in the VP neuron and induced by single action potentials in the synaptically coupled layer VI neuron. (The neurons were coupled in the corticothalamic direction only). (C Upper) Trial-to-trial variability in unitary EPSP amplitude showing large number of trials in which presynaptic action potential did not induce an EPSP. (C Lower) Distribution of unitary EPSP amplitudes (excluding failures).