The Number and Density of Bumblebee (Bombus impatiens) Neurons Across a Range of Brain Volumes

Abstract

Brains can differ in size for many reasons: the head that houses them is a certain size, restricting the volume inside; it would be impractical to have a large brain when your body is too small to carry around its weight; the volume taken up by the cell bodies differs. This last example is the focus of this research. Specifically, I looked at the clustering or density of cell bodies in the bumblebee brain (Bombus impatiens) inside the calyx of the mushroom body, where cells are typically small, and around the antennal lobe, where cells tend to be bigger. The density as well as the area range of these cell bodies were found using a grid counting system. I also found the total brain volume of each specimen (N=6), so I could compare the number of cell bodies counted to the brain volume. The results show that cell bodies are more densely packed in smaller volume brains and total cell body number increased with whole brain volume. There are many possible reasons for this trend and more research is needed to offer a solid answer.