Fig. 4. (A,B) Spontaneous action potentials in the two olfactory receptor neurons
(ORNs) in a trichoid sensillum, distinguishable by their amplitudes. The three
parts in A are one continuous sequence. The action potentials of neither class
were randomly distributed, but (both) exhibited bursting activity. Bursts of
large action potentials are marked with filled circles, bursts of small action
potentials with open circles. The indicated burst (star) is shown on an
enlarged time scale in B. (C) A burst of large action potentials from a
different recording, illustrating the reduction in amplitude of the action
potentials. (D) Action potential bursts were also recorded with tungsten
electrodes placed near the hair base. The three parts of D are one continuous
trace, highpass-filtered at 5 Hz.
