Lateralisation of short- and long-term visual memories in an insect

The formation of memories within the vertebrate brain is lateralised between hemispheres across multiple modalities, however, in invertebrates evidence for lateralisation is restricted to olfactory memories, primarily from social bees. Here we use a classical conditioning paradigm with a visual conditioned stimulus to show that visual memories are lateralised in the wood ant, Formica rufa. We show that a brief contact between a sugar reward and either the right or left antenna (reinforcement) is sufficient to produce a lateralised memory, even though the visual cue is visible to both eyes throughout training and testing. Reinforcement given to the right antenna induced short-term memories whereas reinforcement given to the left antenna induced long-term memories. Thus, short- and long-term visual memories are lateralised in wood ants. This extends the modalities across which visual memories are lateralised in insects and suggests that such memory lateralisation may have evolved multiple...