Fig. 3. Synaptic events in Retzius neurones. (A) Selected simultaneous recordings from a pair of Retzius neurones. V₁ is the recording from one of the neurones and V₂ is the recording from the other. The amplitudes of excitatory synaptic potentials (EPSPs) varied from one neurone to the other and from one event to the next in the same neurone (examples are marked by the asterisks). The arrows point to events that are slower and smaller than those in their contralateral partners, suggesting their spread from the other neurone. An example of a large EPSP can be seen at the bottom of the figure. (B) Amplitude distribution of EPSPs showing populations of small and large events (N=686). (C) The small events had monotonic rise times. (D) The large EPSPs had complex rising phases, suggesting the summation of several EPSPs. Note the scale differences between C and D.