Figure 4. Characteristics of the electrotonic coupling between PCs in the neocortex.

A. CCs are virtually symmetrical at the same current steps of depolarization and hyperpolarization. B. Linear relationship between pre- and post-junctional depolarizing responses. C. Linear relationship between pre- and post-junctional hyperpolarizing responses. D. Postjunctional spikelets are linearly correlated to the gradually enhancing prejunctional responses (CCs in the graph are color-coded with the superimposed traces of pre- and post-junctional responses). E. Amplitudes of spikelets induced by a pre-junctional response remained unchanged at different postjunctional membrane potentials. F. Comparison of asymmetrical CCs of pyramidal electrotonic couplings with symmetrical CCs of interneuron gap junctions. The CC label numbers correspond to the image numbers in Fig. 1 . The CCs included step-CCs of pairs No. 2, No. 3, No. 6 & No. 10 and spikelet-CCs or AP-CCs of the other pairs. Note: All responses were recorded at −70 mV except those in E. Traces were recorded from PFC slices of a 6 week ferret for B and a P32 rat for A, C, D, and E, respectively.