Spontaneous bursts are better indicators of tetanus-induced plasticity than responses to probe stimuli

We culture dissociated mouse cortical neurons in a dense monolayer on multi-electrode arrays, which allow us to stimulate and record from thousands of neurons. Tetanization has been widely used in the study of long-term plasticity. Stimulus-evoked responses constantly change (drift), which makes it difficult to observe the changes caused by the plasticity inducing tetanic stimulation. The most robust pattern of activity in these cultures is spontaneous culture-wide bursting. We studied the effect of tetanization on the properties of spontaneous bursts. We show that the burst-based quantity, spatial extent, does not drift and shows significant change after tetanization. Thus, a burst-based quantity might be a more robust method to study long-term plasticity compared to stimulus-evoked responses