The neural mechanisms underlying bumblebee visual learning and memory

Abstract

Learning and memory offer animals the ability to modify their behavior in response to changes in the environment. A main target of neuroscience is to understand mechanisms underlying learning, memory formation and memory maintenance. Honeybees and bumblebees exhibit remarkable learning and memory abilities with a small brain, which makes them popular models for studying the neurobiological basis of learning and memory. However, almost all of previous molecular level research on bees’ learning and memory has focused on the olfactory domain. Our understanding of the neurobiological basis underlying bee visual learning and memory is limited. In this thesis, I explore how synaptic organization and gene expression change in the context of visual learning. In Chapter 2, I investigate the effects of color learning and experience on synaptic connectivity and find that color learning result in an increase of the density of synaptic complexes (microglomeruli; MG), while exposure to color information may play a large role in experience-dependent changes in microglomerular density increase. In addition, microglomerular surface area increases as a result of long-term memory formation. In Chapter 3, I investigate the correlations between synaptic organizations and individual performance and the results show that bees with a higher density of microglomeruli in visual association areas of the brain are predisposed to faster learning and better long-term memory during a visual discrimination task. In Chapter 4, I explore the genes involved in visual learning and memory by transcriptome sequencing and I show the unique gene expression patterns at different times after visual learning. In summary, my findings shed light on the relationship between synaptic connections and visual learning and memory in bees at the group and individual level and show new candidate genes involved in visual learning, which provide new avenue for future study.