Sci China B. 1990 Aug; 33(8): 938-45.

The role of frontal neurons in pain and acupuncture analgesia.

Liu JL, Han XW, Su SN.

Institute of Space Medico-Engineering, Beijing, PRC.

To study the role of frontal neurons in pain and acupuncture analgesia, experiments were carried out on 4 monkeys (Macaca mulatta) during performing two tasks, the Heat Discrimination Response GO/NO-GO Task (Task I) and the Heat Delayed Discrimination GO/NO-GO Task (Task II). After a criterion of 90% of correct performances over three successive days had been reached, activity of single neurons was recorded from the frontal cortex. Of 276 Task I-related neurons, 211 responded to noxious and/or innocuous heat stimuli. Of 73 Task II-related neurons, 59 responded to noxious and/or innocuous heat stimuli. During acupuncture, the nociceptive reaction time for lever release to avoid painful stimuli was increased, the percentage of correct performances was lowered, and the neuronal responses to noxious and/or innocuous stimuli were suppressed. These neurons were mainly located in a circumscribed area medial to the superior ramus of the arcuate sulcus in frontal cortex, including the prefrontal and premotor areas. It is suggested that neurons in this area may be related to the discrimination of noxious and innocuous stimuli. The suppression of the activity of these neurons during acupuncture may be involved in the whole mechanism of acupuncture to facilitate the production of analgesia.