Are there two honeybees in one honeybee brain?

We do not know if two sides of the insect brain share information in a manner that enables the insect to exhibit a sense of a single individual, that is, a unitary ‘I’. For a unitary ‘I’ to be exhibited by the organism, it requires the organism to have the meaning of the stimuli in terms of what the stimulus is, that is, the identity of the stimulus, and the learned behavioral significance of the stimuli, referred to as valence, to be the same in both halves of the brain. The use of olfactory proboscis extension response (PER) and visual PER conditioning paradigms in honeybees establishes a solid foundation for investigating questions concerning learning, memory, and the mechanisms of sensory information processing. Previous studies have shown that olfactory information learned on one side is not accessible on the contralateral side. For olfactory learning and memory, a honeybee’s brain functions as if two independent learning systems coexist within it. Using a modified PER conditioning protocol, this study examines whether such independence exists for visual learning and olfactory inhibitory learning. We also probe whether the valence sensed with an inhibitory conditioned stimulus learned on one side is accessible for learning on the contralateral side. In each of these cases, we see that, just as with olfactory PER conditioning, memory and valence are accessible only on the trained side, supporting the idea that the honeybee brain acts as if there are two bees in one bee brain.