Brain energy metabolism as an underlying basis to slow-fast cognitive phenotypes in honeybees.

ABSTRACT

In the context of slow-fast behavioral variation, fast individuals are hypothesized to be those who prioritize speed over accuracy while slow individuals are those which do the opposite. Since energy metabolism is a critical component of neural and cognitive functioning, this predicts such differences in cognitive style to be reflected at the level of the brain. We tested this idea in honeybees by first classifying individuals into slow and fast cognitive phenotypes based on a learning assay and then measuring their brain respiration with high-resolution respirometry. Our results broadly show that interindividual differences in cognition are reflected in differences in brain mass and accompanying energy use at the level of the brain and the whole animal. Bigger brains had lower mass-specific energy usage and those bees with bigger brains had a higher metabolic rate. These differences in brain respiration and brain mass were in turn associated with cognitive differences such that fast cognitive phenotypes were those bees with bigger brains while slow cognitive phenotypes were those with smaller brains. We discuss these results in the context of the role of energy in brain functioning and slow-fast decision making and speed accuracy tradeoff.