Caffeine is the most popular neuroactive compound used on the planet and is the main compound used in tea and coffee. In humans and mammals, it is known from previous studies, that caffeine improves alertness and arousal, but its impacts on specific behaviors are still arguable. The effects of caffeine on memory are not clear like those of arousal. The widespread chronic use of caffeine, makes research in humans complicated. Invertebrates are beneficial to this field of research because they have simpler nervous systems, are easy to manipulate, are behaviorally complex, and can solve a variety of cognitive tasks. The authors conducted an experiment to evaluate the effects of caffeine on learning and memory in the honey bee. In addition, they hypothesized that if caffeine enhances memory, then bees would be able to perform better at learning and memory tasks. To test this hypothesis the researchers performed an olfactory and visual conditioning test.
The olfactory conditioning study was tested with a proboscis extension reflex (PER) study. This study uses classical conditioning in which an odor is paired with a rewarded sucrose solution. In the visual conditioning, a delayed match to sample (DMTS) and a Y-max experiment were used. The delayed match to sample experiment was useful in assessing working memory and to learn abstract concepts. The Y-maze experiment had the same protocol as the DMTS experiment, but with a single visual stimulus associated with sucrose. In the olfactory conditioning test, newly emerged bees were collected every day and a drop of different caffeine concentrations was placed its thorax. Bees were tethered in thin-walled aluminum tubes using strips of tape, then classical conditioning was performed. The delayed match to sample and Y- maze experiments consisted of an artificial feeder containing a sugar solution. Findings suggest that caffeine enhances learning and memory. The bees in the caffeine group could recall more than in the control group. In like matter, in the delayed match to sample and Y- maze experiments, the bees of the caffeine group performed statistically significantly better than the control group.
Si, Zhang, & Maleszka based the study on several past experiments in humans. The article describes that previous studies did not find an effect on long-term memory in humans and monkeys. They said that previous experiments lacked accuracy due to variations in genomics and chronic use of caffeine. The authors clarified those results with the olfactory and visual experiments in the honey bee. Si, Zhang, & Maleszka explained every aspect of the experiment, and they noted that part of the bees in the control and caffeine groups failed to perform the delayed-matched performance test. However, even with the lack of bees, they concluded that bees in the caffeine group performed better. This conclusion is questionable given that they did not state the number and the reason of why the bees failed to perform the test. Moreover, the experimenters did not explain if the bees died because of the high or low concentration of caffeine or sucrose. In like manner, the percentage of bees failing to respond to sucrose remained high. Much of the study remains questionable since they did not explain if the concentration of caffeine or sucrose that was used was the same that the bees use in their natural habitat. In the olfactory association test, that the performance in bees was not significant until the sixth day. This leaves the reader thinking that the performance of the bees could be due to the development of the brain instead of the actual caffeine. The discussion of the article contained future considerations and possibilities for improvements.
The article is well written and comprehensible for an audience with a knowledge of science. The discussion section of the article correlates with the information provided in the rest of the article. All the terminology employed throughout the article was explained to be easily understood. The article consisted of grammatically correct sentences and flow easily.
Overall, the article is straightforward and easily understandable. It is a well-written article with important findings of science in regards to caffeine and learning. It is relevant and has a very convincing hypothesis, but still needs a more concrete way of approaching this complex problem.