Scientists from Queen Mary University of London argue in a new paper published in the Proceedings of the Royal Society B that insects most likely have central nervous control of nociception (detection of painful stimuli); such control is consistent with the existence of pain experienced and has implications for insect farming, conservation, and laboratory treatment.
|According to Gibbons et al., insects have central nervous control of nociception, which is consistent with the existence of pain experience. Krzysztof Niewolny provided the image.|
Nociception modification enables animals to improve their chances of survival by adapting their behavior in different contexts.
In mammals, this is known as the descending control of nociception and is carried out by neurons from the brain.
It has rarely been investigated whether insects have such control or the neural circuits that allow it.
"Nociception is the detection of potentially or actually harmful stimuli, which is mediated by specialized receptors called nociceptors," said Professor Lars Chittka of Queen Mary University of London and colleagues.
"It may be accompanied by a sense of pain, which is a negative subjective experience produced by the brain."
"Neuroanatomical and neurobiological evidence showing that the insect brain can facilitate or suppress nocifensive behavior, as well as molecular studies revealing pathways involved in the inhibition of nocifensive behavior both peripherally and centrally," the researchers write.
Many areas of insect and human neuroscience benefit from the presence of descending nociception controls in insects.
Because the descending control of nociception in humans can affect pain perception, it is possible that a form of pain perception exists in insects and can be modulated similarly.
"Mammalian researchers quantify pain by observing non-reflexive, complex, and long-lasting changes in the animal's natural behavior, which are most likely mediated by descending controls," the researchers wrote.
"Reduced feeding, locomotion, and burrowing behaviors, for example, are used as pain indicators in rodents."
"As a result, examples of insects engaging in these types of behaviors may support the idea of pain in insects."
"For example, insects are less attracted to appetitive stimuli if they are also exposed to nociceptive stimuli." Furthermore, recent evidence demonstrating sentience-linked cognitive abilities in some insects, as well as studies indicating pain perception in other invertebrates, supports this idea."
"This is morally significant because insects are frequently subjected to potentially painful stimuli in research and farming," they said.
"An important consideration for modeling human pain disorders is the possibility of pain sensations in insects."
"Because of genetic and behavioral similarities to human nociception, the fruit fly Drosophila melanogaster is currently used as a model organism for human pain research."
"Abnormal and persistent pain states in humans appear to be caused by dysfunction of descending pain controls; therefore, if insects have descending nociception controls, they may be viable models for human pain disorders."
Reference : doi: 10.1098/rspb.2022.0599