Fig. 5.

Intracellular recordings of antennal lobe projection neurons during antennal stimulation with pheromone. a This neuron is initially inhibited by a stimulus that contains C15, followed by strong depolarization and again inhibition (third and fourth trace). The neuron shows an inhibitory response to bombykal (BAL) and a blend effect to the pheromone blend of C15 + BAL. In each trace, the ipsilateral antenna receives five 50-ms stimulus pulses at 5 Hz (stimulus markers are shown beneath the records). b When the neuron is depolarized by injecting current through the recording electrode, the overall firing frequency increases and the first stimulus pulse of BAL evokes a distinct reduction in firing (inhibition). c Laser scanning confocal micrograph showing intracellular labeling of two PNs in the AL. Anatomy of the PN in (colored red here, stained with biocytin) described in a, b and a uniglomerular projection neuron described in d, e (colored green here, stained with Lucifer Yellow) (frontal view). The red neuron branches in the cumulus and not in the toroid-1 or any other glomerulus. The green neuron innvervates one ordinary glomerulus. C cumulus, do dorsal, G ordinary glomerulus, la lateral, me medial, T1 toroid-1, T2 toroid-2. Scale bar 100 μm. d Intracellular recordings from a uniglomerular projection neuron. Stimulation with bomybkal, C15, or a blend of both pheromone components reduces firing. In each trace, five identical stimulus pulses are delivered to the ipsilateral antenna at a frequency of 5 Hz (stimulus markers for the 50-ms pulses are shown beneath the records). e In the same neuron, the inhibition is also observed in response to stimulation with the pheromone blend when injecting depolarizing current into the neuron to increase the overall firing of the neuron. Only the first pheromone stimulus evokes an inhibition