Effect of ghrelin on network activity. Raster plots of the neuronal activity recorded over 20 minutes (x-axis) in cultures incubated with ghrelin and controls at age DIV 6. The top rows of the panels depict only the electrodes in contact with active neurons (electrode numbers are on y-axis). Each tick represents a recorded action potential. The bottom rows of the two panels represent the summed network activity. (A) Network activity in a sister culture under control conditions, 47 spikes recorded in 1 minute. (B) Network activity in a culture chronically treated with ghrelin, 3740 spikes recorded in 1 minute.