Shape of frequency-current curves in CAI pyramidal cells in the hippocampus

Frequency-current curves for CA1 hippocampal pyramidal neurons are shown to have basically the same shape as those for spinal motoneurones, with a region of shallow slope at low frequencies, preceding a sleep linear or upward convex region at higher frequencies. The frequency range is, however, displaced towards lower frequencies. The results suggest, in a qualitative sense, that the firing behaviour of CA1 pyramidal cells is regulated by the afterhyperpolarization, at least in the low frequency range.