Figure 3. H₃ receptor activation desynchronizes action potential firing in CA3 pyramidal cells.

A, concomitant recordings of cellular action potential firing and extracellular gamma oscillations. Lower traces are excerpts from the upper traces at increased temporal resolution. H₃ receptor activation results in a decreased gamma oscillation amplitude. B, the average oscillation cycles of the traces in A are shown in the diagrams. The histograms show 2 ms bin counts of action potentials occurring during the oscillation cycles. The detected number of cycles are roughly the same before and after RAMH. Fitted to the histograms are 3rd order polynomial functions (see Methods). In kainate-only conditions action potentials show a clear synchronization and phase preference. H₃ receptor activation causes action potential firing to become desynchronized, which is reflected in the flatter profile of the histogram and a lower ‘a’ coefficient. C, summary diagram showing the ‘a’ coefficients before and after H₃ receptor activation.