Pain: Less pain when you're in control?

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Pain: Less pain when you're in control?

from Nature Reviews Neuroscience

Archibald

Our responses to pain and our ability to tolerate it are known to be

affected by the extent to which pain is perceived to be controllable. A

study published in The Journal of Neuroscience now shows how differences

in perceived pain control influence the activation of the insular

cortex, secondary somatosensory cortex (SII) and anterior cingulate

cortex (ACC), all of which are involved in pain processing.

Salomons et al. used painful thermal stimuli and different cues

signalling controllable or uncontrollable pain to test whether subjects'

perception of pain and the associated neural processing varied according

to perceived controllability. Although the subjects were able to

distinguish between cues signalling controllable and uncontrollable

pain, there was no difference between the mean pain rating given for

stimuli perceived to be controllable or uncontrollable.

The authors also used overlapping brain maps created using fMRI studies,

and subtracted the activation seen in areas of interest when pain was

perceived to be controllable from that seen when pain was perceived to

be uncontrollable. Although parts of all three areas were activated when

pain was perceived to either be controllable or uncontrollable, the

degree of activation was significantly greater when pain was perceived

to be uncontrollable; in particular in the dorsocaudal area of the ACC

and the anterior area of the right insula. As the subjects did not give

the two conditions different pain ratings, Salomons et al. conclude that

the results of the overlap study cannot be explained by just the

subjects' perception of pain.

The authors suggest that the results of previous pain studies might have

been influenced by subjects' perceived lack of pain control, which, in

imaging studies, could have led researchers to believe that pain itself

caused exaggerated activation of particular areas of the brain. They

also propose that further research be carried out to establish whether

different subjects use different techniques, such as distraction, to

help them cope with pain. Furthermore, they suggest that differences in

perceived pain control might be used in studies of chronic pain and

possible treatments for this condition.

References

ORIGINAL REFERENCE PAPER

Salomons, T. V. et al. Perceived controllability modulates the neural

response to pain. J. Neurosci. 24, 7199–7203 (2004)

FURTHER READING

Hunt, S. P. The molecular dynamics of pain control. Nature Rev.

Neurosci. 2, 83–91 (2001)