Fig. 2. (A) Short-term synaptic plasticity between soma–soma paired Lymnaea neurons. Presynaptic neuron visceral dorsal 4 (VD4) and its postsynaptic partner left pedal dorsal 1 (LPeD1) were paired in a soma–soma configuration and cells allowed to develop synapses overnight. Simultaneous intracellular recordings revealed excitatory synapses where induced action potentials in VD4 (first open arrow) generated 1:1 excitatory postsynaptic potentials in LPeD1. Following a burst of action potentials in VD4 (at bar) the subsequent action potentials in the presynaptic cell (at closed arrow) induced 1:1 spikes in the postsynaptic cell. This short-term change in the postsynaptic cell's response to the presynaptic action potentials illustrates the plasticity in the system. (B) Synaptic potentiation on a silicon chip. Cells were soma–soma paired overnight and synaptic physiology studied through the chip. The upper traces show intracellular voltages in red, the lower traces represent capacitor stimuli (left) and transistor records (right) in black. (a) Control recordings. Capacitor stimulation of the presynaptic neuron VD4 generated action potentials that did not elicit a detectable response in the postsynaptic cell LPeD1 (right). (b) Stronger capacitive stimulation through the chip induced bursts of spikes in VD4. (c) Post-tetanic action potential in VD4 now induced 1:1 action potentials in LPeD1 (right). Figure taken from (Kaul et al., 2004).