Diane
02-04-2007, 02:51 PM
Barrett, you will read this (http://www.painonline.com/mt-archives/2007/04/trying_to_see_p.html#more) from www.painonline.com , and say, I knew this all along.
Excerpt:
These authors identified areas of hyperstimulation on EEG-functional MRI, but THEN, found that with increasing the pain, these same areas actually underperfused. then, to make things even more interesting, when the pain was really crnked up, the same areas could be seen to be hyperactive, but it was in the MOTOR areas not the sensory areas. Try reasoning that one out....
When the pain was increased, "Higher unpleasantness rating was associated with SUPPRESSION of activity in areas known to be involved in stimulus categorization and representation (ventral premotor cortex, PCC, parietal operculum, insula) and enhanced activation in areas initiating, propagating, and executing motor reactions (ACC, SMA proper, cerebellum, primary motor cortex)
Furthermore, time was a factor in that, the "BOLD (blood oxgyen level dependent) signal change decreased in SI over time. Dipole strength of the ACC source decreased over the experiment and increased during the stimulation block suggesting sensitization and habituation effects in these areas."
This article is consistent with an article by Coen et al in Am J Physiol Gastrointest Liver Physiol. 2007 Mar 29. This imaging study also found habituation resulting in decreased functional imaging signal over time, due to habituation to painful stimulation of the esophagus.
This makes is all harder. There are stages of pain response, and with time it all decreases due to the brain's tendency to accomodate to habituation.
Future investigators will have to get the time factors down when claiming to image pain. Perhaps as pain increases, the motor areas which might give a response to the pain become more active, and later, with acommodation to the pain, the signal may lessen. This is a much more complex interpretation scheme than has been followed in the past. My bold. Is this not what you've said now for years?
Excerpt:
These authors identified areas of hyperstimulation on EEG-functional MRI, but THEN, found that with increasing the pain, these same areas actually underperfused. then, to make things even more interesting, when the pain was really crnked up, the same areas could be seen to be hyperactive, but it was in the MOTOR areas not the sensory areas. Try reasoning that one out....
When the pain was increased, "Higher unpleasantness rating was associated with SUPPRESSION of activity in areas known to be involved in stimulus categorization and representation (ventral premotor cortex, PCC, parietal operculum, insula) and enhanced activation in areas initiating, propagating, and executing motor reactions (ACC, SMA proper, cerebellum, primary motor cortex)
Furthermore, time was a factor in that, the "BOLD (blood oxgyen level dependent) signal change decreased in SI over time. Dipole strength of the ACC source decreased over the experiment and increased during the stimulation block suggesting sensitization and habituation effects in these areas."
This article is consistent with an article by Coen et al in Am J Physiol Gastrointest Liver Physiol. 2007 Mar 29. This imaging study also found habituation resulting in decreased functional imaging signal over time, due to habituation to painful stimulation of the esophagus.
This makes is all harder. There are stages of pain response, and with time it all decreases due to the brain's tendency to accomodate to habituation.
Future investigators will have to get the time factors down when claiming to image pain. Perhaps as pain increases, the motor areas which might give a response to the pain become more active, and later, with acommodation to the pain, the signal may lessen. This is a much more complex interpretation scheme than has been followed in the past. My bold. Is this not what you've said now for years?