Response competition associated with right-left antennal asymmetries of new and old olfactory memory traces in honeybees

Lateralized recall of olfactory memory in honeybees was tested, following conditioning of the proboscis extension reflex (PER), at 1 or 6 h after training. After training with lemon (+)/vanilla (-) or cineol (+)/eugenol (-) recall at 1 h was better when the odour was presented to the right side of the bee than when it was presented to the left side. In contrast, recall at 6 h was better when the odour was presented to the left than to the right side. This confirmed previous evidence of shorter-term recall via the right antenna and long-term memory recall via the left antenna. However, when trained with either a familiar appetitive odour (rose) as a negative stimulus, or with a naturally aversive odour (isoamyl acetate, IAA) as a positive stimulus, bees showed suppression of the response from both the right and the left side at 1 h after training (likely due to retroactive inhibition) and at 6 h responded to both odours on both sides. We argued that at 6 h, when access to memory has com...