Arm injury produces long-term behavioral and neural hypersensitivity in octopus
Jean S. Alupay,Stavros P. Hadjisolomou,Robyn J. Crook
Complementing Robyn's OTHER paper on squid, this study investigates the possibility of pain experiences in octopuses.
Jean S. Alupay,Stavros P. Hadjisolomou,Robyn J. Crook
Complementing Robyn's OTHER paper on squid, this study investigates the possibility of pain experiences in octopuses.
Highlights
- Arm injury evokes hypersensitivity to touch and wound-directed protective behavior
- Low-threshold and nociceptive mechanosensory neurons sensitize after injury.
- Pattern of acute (5 min) and persistent (24 h) neuronal hyperexcitability is similar.
- Distinction between pain and nociception in octopus is more complex than in squid.
Abstract
Cephalopod molluscs are the most neurally and behaviorally complex invertebrates, with brains rivaling those of some vertebrates in size and complexity. This has fostered the opinion that cephalopods, particularly octopuses, may experience vertebrate-like pain when injured. However, it is not known whether octopuses possess nociceptors or if their somatic sensory neurons exhibit sensitization after injury. Here we show that the octopus Abdopus aculeatus expresses nocifensive behaviors including arm autotomy, and displays marked neural hyperexcitability both in injured and uninjured arms for at least 24 h after injury. These findings do not demonstrate that octopuses experience pain-like states; instead they add to the minimal existing literature on how cephalopods receive, process, and integrate noxious sensory information, potentially informing and refining regulations governing use of cephalopods in scientific research.
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