Honeybees, Stop Signals, and Neural Networks
Talia Borofsky is an undergraduate at Swarthmore College graduating in May 2018. The video to the right is from an interview in September 2016.
Hive minded: like neurons, honeybees collectively integrate stop signals to regulate forager recruitment
Authors: Talia Borofsky, Rebecca Zhou, Victor Barranca, and Christopher Mayack
Neurons and eusocial insects display collective decision-making, whereby groups of individuals determine how to respond to a changing environment. Crucially, no one individual has to know that a decision is taking place. Honeybees use collective decision-making to allocate foragers to profitable food sources. A recruitment signal called the waggle dance provides positive feedback during this process. We examined whether negative feedback, via the stop signal, down-regulates waggle dancing and allocates foragers away from food sources that have recently ceased to be nutritious. We trained bees to a high 2.5 M sucrose solution feeder, and then lowered the sucrose concentration to 0.75 M. We recorded feeder visits, waggle dances, waggle dance pheromones, and stop signals received by trained bees. A spike of stop signals targeted waggle dancing bees, mostly from untrained individuals (contra signaling), immediately after the feeder switch. Following this burst, waggle-dancing and waggle dance pheromones decreased. Surprisingly, previously trained bees visited the poor quality feeder more frequently. We then modeled the waggle dance activity of foragers as they decided between two potential food sites. To do so, we adjusted a neural firing rate model that integrated food quality, waggle dances, and stop signals according to a sigmoidal gain curve. We found that adding a spike of stop signals was enough to reproduce the dynamics shown in the experiment. Our results suggest that: (1) foraging frequency appears to be regulated at an individual level, (2) neural networks and honeybee colonies integrate positive and negative feedback according to similar network properties.