Fig 8. Model of putative AL network explaining how sustained suppression can be established by plant odor and pheromone interactions.

In the situation where a plant odor (A) is paired with a pheromone (P) stimulus, corresponding OSNs (A + P) are activated simultaneously, which drives strong activation of inhibitory LNs (IA) such that the resulting excitation of PNs in the OG (A) and in the MGC (P) is suppressed compared to when the plant odor or the pheromone appears alone. The strong coincidental activation of the LNs (IA) causes a strengthening of the inhibitory synapses (x1 and x2), such that responses to subsequent stimuli with the plant odor (A) or the pheromone (P) are suppressed. In the situation where a plant odor (B) is presented alone without the pheromone, the resulting activation of connected LNs (IB) is weaker. Thus, strengthening of the inhibitory synapses onto the PNs does not occur (y1 and y2), leaving the PN responses unaltered.