Figure 4.

Single-sensillum recordings from control and Or43b mutant ab8A neurons. Extracellular recordings from ab8 sensilla in control w¹¹¹⁸ flies, Canton-S flies, and the two mutant strains Or43b¹ and Or43b². The traces show the activity of the ab8A (open circles) and ab8B (filled circles) neurons after stimulation with 1-hexanol at a dilution of 10^–3. In w¹¹¹⁸ and Canton-S flies, this concentration of 1-hexanol elicits a strong excitatory response of the A neuron but not the B neuron. Although ab8A neurons display spontaneous activity, they do not show a normal excitatory response to odors in Or43b mutants. Spontaneous activity in ab8A neurons in Or43b mutants often occurs in short bursts of two to three action potentials. The thick horizontal bar indicates the stimulation period (500 msec). Spike classification was performed as discussed previously (de Bruyne et al., 2001).