Clock-spiking cells not only in the eye of the fly, but also in the antenna!

Abstract

During the course of single cell olfactory recordings from the funicular part of the antenna of Drosophila virilis we encountered a pair of cells firing synchronously and consistently at a rate of about 9 to 14 spikes per second. Every spike was seen to consist of a spike complex made up of two separate biphasic components thought to originate from two separate cells. The larger action potential, appearing first, had a peak-to-peak (ptp) amplitude of up to 200 microV followed closely by a smaller spike with an amplitude of about 60 microV. The repetitive firing pattern was not affected by air or odour puffs. This kind of consistent spontaneous spiking activity of two closely associated cells resembles remarkably closely the clock-spikes hitherto known only from the eyes of flies. Our encounter with such cells in a sense organ other than the eye poses many new questions and could lead to a renewed effort to understand the role(s) of the clock -spiking cells as possible oscillatory components of the dipteran pacemaking system in particular and the insect nervous systems, generally.