Fig. 7. Intracellular recordings from an MG cell. Molecular layer stimulation (arrows) was adjusted initially below threshold for evoking a postsynaptic action potential and was then applied repetitively at a frequency representative of the natural electric organ discharge (EOD) rhythm during increased sensory attention. Postsynaptic responses increased with the number of stimuli, leading to the generation of partial (arrowhead) and then full backpropagating broad spikes (asterisk), and to increasing numbers of small narrow spikes (probably axon spikes). Note that a slow depolarization, lasting several hundred ms, builds up with repetitive stimulation. The inset (top right) shows a plot of the probability of evoking a broad spike as a function of the number of stimuli applied.