Postembryonic Development and Adult Plasticity of the Mushroom Bodies in the Honey Bee Brain

The mushroom bodies are distinctive, paired neuropils in the insect brain. Convergence of numerous sensory modalities in the mushroom bodies indicates that they may be a center for sensory integration. Ablation and lesioning experiments have also established a role for this brain region in olfactory associative learning, context-dependent learning, and spatial learning. Foragers in social insect colonies must leave the colony in search of food numerous times each day, a behavior that requires a highly developed capacity for spatial orientation. Honey bee foragers, have a greatly increased volume of mushroom body neuropil relative to newly enclosed bees. This volume increase may reflect plasticity of the adult brain in preparation for, or as a consequence of, the cognitive demands of foraging behavior. In this series of studies, we investigate the development of the mushroom bodies in larval, pupal and adult honey bees at the cellular and molecular level. BrdU immunocytochemistry reveals a concentric organization of neurons about each neuropil center that is stratified by birthdate. The developing honey bee mushroom bodies are derived from nearly 2000 neuroblasts, far more than has been observed in any other insect. The transcription factor myocyte enhancer factor 2 (MEF2) is used to label a specific subpopulation of mushroom body neurons. MEF2 expression is first seen in newborn cells that are just beginning neuronal differentiation. The cloned honey bee MEF2 homolog is highly conserved with respect to vertebrate MEF2 proteins in the DNA binding and dimerization regions. Vertebrate p38 MAPK activation sites are conserved in honey bee MEF2, indicating that insect MEF2 proteins are also regulated by p38 MAPK MAPKs have been shown to be involved in vertebrate learning and memory. Finally, Golgi analysis of the dendritic arbors of mushroom body intrinsic neurons reveals that increasing age and neuropil volume can typically be correlated with dendritic outgrowth. Increasing amounts of foraging experience are reflected by similarly increasing amounts of dendritic branching and lengthening. In conclusion, the honey bee provides an excellent model for the study of the relationship between neuroanatomy, gene expression, and learning in the context of a natural and ecologically relevant behavior.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Entomology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Farris, Sarah Marie

Contributors dc:contributor

• Susan F. Fahrbach
• Robinson, Gene E.

• Biology, Entomology

Language dc:language

eng

Identifier

(MiAaPQ)AAI9955612

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/86482