Recording brain activity in vivo during learning is fundamental to understanding how memories are formed. We used functional calcium imaging to track odor representations in the primary chemosensory center of the honeybee, the antennal lobe, while training animals to discriminate a rewarded odor from an unrewarded one. Our results show that associative learning transforms odor representations and decorrelates activity patterns for the rewarded versus the unrewarded odor, making them less similar. Additionally, activity for the rewarded but not for the unrewarded odor is increased. These results indicate that neural representations of the environment may be modified through associative learning.