Fig. 2. Spontaneous synaptic activity in Retzius neurones. (A) Simultaneous somatic recordings of Retzius neurones in leech Ringer’s solution showing spontaneous and synchronous excitatory postsynaptic potentials. V1 is the recording from one of the neurones and V2 is the recording from the other. Six consecutive series are shown. (B) Partial substitution of Ca2+ by Mg2+ in the Ringer’s solution abolished the spontaneous activity in both neurones. (C) Synaptic activity was restored in normal Ringer’s solution.
