Bees are fascinating creatures.
At BBC Earth they have a really interesting article on a study done in the Free University of Berlin by scientist Randolf Menzel and his colleagues that used Pavlovian training methods to see how bees retain memory and develop during sleep. Deep sleep consolidates memories in humans and the goal of the experiment was to see if the same could be true about the honeybee.
First, they had to teach them something new; only then could they test the quality of their short-term to long-term memory transfer. They chose a tried-and-tested protocol, developed by Menzel himself in 1983.
When feeding, honeybees exhibit a stereotyped behaviour: sticking out their long tubular mouthparts, or proboscis, to slurp up dinner. But, by presenting honeybees with a specific odour and burst of heat as they feed, this proboscis extension response (PER) can be elicited even when there is no food available.
If any of this sounds familiar, it all runs similarly to Pavlov’s famous experiments with the conditioned response with dogs. However, the prompt was the odor-heat combo that would trigger a feeding instinct rather than Pavlov’s bell.
One of the fascinating things about the study is that it took less time to condition the bees than it did to condition the dogs. Honeybees are quick learners and they associated the odor and heat with food after only three trials.
From the article.
"If you work with them, you realise very quickly that they are very smart," says Hanna Zwaka, one of the study's authors. "They are also very sweet to watch while they are learning."
Once conditioned, the bees were allowed a full night's sleep within their own personalised plastic tube. As they slept in solitude, the team exposed some of the honeybees to the conditioned odour-heat combo during different sleep stages, ranging from light sleep to deep sleep, allowing any activity in their brains to be further stimulated.
As a control, a separate group of bees were exposed to a neutral odour – paraffin oil – that would not reactivate any conditioned responses.
When the honeybees woke the next day, the memory tests could begin. Did the bees with the night-time reminders hold on to their conditioned response – sticking out their proboscis – for longer than those without?
The study discovered that the odor-heat combination only worked when the bees were in a deeper sleep state. When they were in the lighter part of their sleep cycle, the odor-heat combo doesn’t have the same effect.
So there are some truly weird and magical things going on in those little bee brains. I will report on more as we learn more.