Pyramid power: Principal cells of the hippocampus unite!

Electrical transmission in the mammalian brain is now well established. A new study by Thomson and colleagues elegantly demonstrates coupling between CA1 hippocampal pyramidal cells, which is far more common than previously supposed. Although the history of coupling is extensive, doubt, predjudice, and technical issues long kept it from wide acceptance. Here "spikelets" or "fast prepotentials" are found when two cells are coupled and in this situation result from electrical transmission of impulses from one coupled cell to the other. Interesting questions remain as to whether connexin or pannexin gap junctions serve as the molecular substrate of transmission, and the role of electrical transmission in hippocampal physiology is uncertain. Increased coupling could well contribute to the known tendency of the hippocampus to exhibit seizure activity.