Figure 4.
Axoaxonic cell-triggered polysynaptic events showing different sensitivity to 5-HT2A receptor agonist. A, Single action potentials in four axoaxonic cells (aac) triggered mono- and polysynaptic events detected in the aac itself (top) and in its downstream pyramidal cells (bottom) innervated mono- as well as polysynaptically in control (left) and in 40 μm α-methyl-5-HT (a-m-5-HT, right). B, Scattergram of the onset of EPSPs (red dots) and IPSPs (blue dots) from 20 consecutive sweeps superimposed from the same experiments as in A in control (left) and in 40 μm α-methyl-5-HT (a-m-5-HT, right). C, Probability histograms from the onset time of EPSPs (gray) and IPSPs (black) constructed from A and B showing the alternating sequences of IPSPs and EPSPs triggered by the axoaxonic cells. The probability of monosynaptic IPSPs and disynaptic EPSPs was unchanged in α-methyl-5-HT, but other polysynaptic events were abolished. A–C show the same time window.