Q2. What is the effect of novelty and predators on the fish?
Other animal studies have shown that exposure to novelty and predators can evoke a stress analgesia with a total reduction in pain reactivity.
Q3. What is the reason why the fish’s attention is dominated by the noxious stimulus?
In the novel object test in which the fish’s attention is dominated by the noxious stimulation, it might be that the OBR does not increase after object presentation because little attention and neural processing can be diverted to this physiologic response.
Q4. What did the animals show when they presented the object?
Although the animals experiencing noxious stimulation did not show fearrelated avoidance behavior, they did show reduced nociception-related behaviors, rocking and rubbing, compared with the frequency of these behaviors before presenting the object.
Q5. What is the common type of opioid receptor in fish?
16 Comparative genetic studies have shown that the opioid receptor family hasbeen highly conserved during evolution, with fish opioid receptors having 91% similarity with human opioid receptors.
Q6. How long did it take to diffuse the analgesic into the blood?
the 30-minute recovery period after morphine injection is likely to be sufficient time for the analgesic to have diffused into the blood and body tissues.
Q7. How much is known about the effects of endogenous opioids in fish?
46 Relatively little is known about the effects of endogenous opioids in fish, although enkephalins and β-endorphins are present in fish neurons.
Q8. How many times was the object presented?
Novel object presentation was repeated an additional 4 times at hourly intervals, and at each presentation a differently shaped and colored novel object was used.
Q9. What is the common interpretation of the study?
In this study nociception-related behavior affected fear responses, and one interpretation is that this noxious treatment might command the majority of the attention capacity in fish subject to this experimental situation.