Electrotonic Coupling between Pyramidal Neurons in the Neocortex
Figure 2
High junctional conductance and AP firing in pyramidal electrotonic couplings in the neocortex.
A. Bi-directional sub-threshold responses to stepped-current injections to either of the coupled PCs. B. The histogram shows notable disparities between pyramidal and interneuron electrotonic couplings. C. A prejunctional AP train induced a mixture of postjunctional APs and spikelets depending upon slight variations of membrane potential levels (inset: A broken line indicates a ‘threshold’ for the induction of either an AP or a spikelet. Asterisks mark truncated APs). D. AP firing was induced due to membrane potential depolarization from a resting level of −70 mV to −60 mV. E. Postjunctional AP firing was generated at resting membrane potential through the summation of spikelets when a 70 Hz prejunctional AP train was triggered. Spikelet summation, to a lesser extent, was also observed at 20 Hz as shown in D. Note: Traces were recorded respectively from the PFC slices of a 6 week old ferret for A, a P18 rat for C and a P32 rat for D & E.