Dumb and Lazy? A Comparison of Color Learning and Memory Retrieval in Drones and Workers of the Buff-Tailed Bumblebee, Bombus terrestris, by Means of PER Conditioning

More than 100 years ago, Karl von Frisch showed that honeybee workers learn and discriminate colors. Since then, many studies confirmed the color learning capabilities of females from various hymenopteran species. Yet, little is known about visual learning and memory in males despite the fact that in most bee species males must take care of their own needs and must find rewarding flowers to obtain food. Here we used the proboscis extension response (PER) paradigm to study the color learning capacities of workers and drones of the bumblebee, Bombus terrestris. Light stimuli were paired with sucrose reward delivered to the insects’ antennae and inducing a reflexive extension of the proboscis. We evaluated color learning (i.e. conditioned PER to color stimuli) in absolute and differential conditioning protocols and mid-term memory retention was measured two hours after conditioning. Different monochromatic light stimuli in combination with neutral density filters were used to ensure that the bumblebees could only use chromatic and not achromatic (e.g. brightness) information. Furthermore, we tested if bees were able to transfer the learned information from the PER conditioning to a novel discrimination task in a Y-maze. Both workers and drones were capable of learning and discriminating between monochromatic light stimuli and retrieved the learned stimulus after two hours. Drones performed as well as workers during conditioning and in the memory test, but failed in the transfer test in contrast to workers. Our data clearly show that bumblebees can learn to associate a color stimulus with a sugar reward in PER conditioning and that both workers and drones reach similar acquisition and mid-term retention performances. Additionally, we provide evidence that only workers transfer the learned information from a Pavlovian to an operant situation

The Use of Bright and Dark Types of Humour is Rooted in the Brain

The ways in which humour can be used are related to the manifold interpersonal functions humour can serve, some of which are positive, and some negative. In the present study, phasic changes in the functional coupling of prefrontal and posterior cortex (EEG coherence) during other people's auditory displays of happy and sad mood were recorded to predict people's typical use of humour in social interactions. Greater use of benevolent humour, the intentions of which are in keeping with the characteristics of "laughing-with" humour, was associated with greater decreases of prefrontal-posterior coupling during the processing of happy laughter. More loose prefrontal-posterior coupling indicates loosening of control of the prefrontal cortex over the incoming perceptual information, thereby opening up the perceptual gate and allowing the brain to become more affected by the social-emotional signals. Greater use of humour styles linked to malicious intentions of "laughing-at" humour was associated with responses indicating a wider opened perceptual gate during the processing of other people's crying. The findings are consistent with the idea that typical humour styles develop in line with the rewarding values of their outcomes (e.g., interaction partners are happy or hurt), which in turn are defined through the individuals' latent interpersonal goals