Context: Although unpleasantness is an essential part of the IASP definition of pain, it is possible to induce a state described as intense pain devoid of unpleasantness in some patients, with morphine injection or psychosurgery. Such patients report that they have pain but are not bothered by it; they recognize the sensation of pain but suffer little, or not at all. Indifference to pain can also rarely be present from birth; these people have normal nerves on medical investigations, and find pain unpleasant, but do not avoid repetition of the pain stimulus.

Question: IASP's definition of pain includes what aspect as an essential part?
Answer: unpleasantness

Question: What is it possible to induce which is, contrary to expectations, devoid of unpleasantness?
Answer: a state described as intense pain

Question: Which type of injection has caused patients to report they have pain but aren't bothered by it?
Answer: morphine

Question: How much do some patients going through psychosurgery suffer from the sensation of pain?
Answer: little, or not at all

Question: What perspective towards pain are some people with perfectly normal nerves born with?
Answer: Indifference

Question: What is an essential part of the AISP definition of pain?
Answer: Unanswerable

Question: What is the result of psychosurgery injection?
Answer: Unanswerable

Question: What is present from birth?
Answer: Unanswerable