D3109: Examining the role of the central complex and mushroom bodies in reversal colour learning in honey bees

The regions of the brain associated with colour learning in the honey bee (Apis mellifera) have yet to be fully ascertained. The mushroom bodies (MB) and the central complex (CX) are two regions that are considered centres of learning and memory; both receive visual input in bees. Thus, both should be considered when attempting to discern the regions of the brain that are involved in colour learning in the honey bee. Few comparative studies examining these two structures have been conducted, and none have used a reversal learning task. In this study, bees initially learned to associate the LED colour (blue or green) of one arm of a y-maze with escape from the y-maze. The bees were then assigned to 1 of 4 treatment groups (procaine-inactivated CX; procaine-inactivated MB; saline-injected CX; saline-injected MB) or 1 of 2 untreated controls. Half the bees then reattempted the initial task to verify memory recall; the other half performed a reversal learning task (associating the opposite colour with escape). Percentage of correct responses and duration of each trial were evaluated. The honey bee MB have been hypothesized to be regions of colour learning, due to their involvement in odour learning and the visual input they receive. However, most insect species do not receive visual input in their MB and thus cannot process colour input in this region. Comparing the MB and the CX in colour learning will yield insights not only into the honey bee, but also other insect species with potential evolutionary implications.