The study team found that compared with sighted subjects, congenitally blind subjects have lower heat pain thresholds, rate suprathreshold heat pain stimuli as more painful than the normal-sighted reported, and have increased sensitivity to cold pain stimuli.
In addition, interesting cultural differences emerged. "There is evidence that, compared to people from northern countries (e.g., Denmark), people in southern countries (e.g., Italy) are more emotionally expressive and responsive to pain," says lead investigator Ron Kupers, PhD, Director of the BRAINlab, Department of Neuroscience and Pharmacology, Faculty of Health and Medical SciencesPanum Institute, University of Copenhagen, Denmark.
The results of the pain questionnaires further demonstrated that blind subjects are more attentive to external threat signals. Dr. Kupers concludes, "We have shown that the absence of vision from birth induces a hypersensitivity to painful stimuli, lending new support to a model of sensory integration of vision and pain processing."
In a commentary accompanying the article, Flavia Mancini, PhD, Institute of Cognitive Neuroscience, University College London, United Kingdom, says, "The novel finding of pain hypersensitivity in blindness has several important implications for both basic and clinical science. This study is noteworthy for research on multisensory interactions and plasticity, because it shows a strong link between vision and pain. The next step is to understand the nature of the interaction between visual loss and pain sensitivity. Which aspect of pain processing is involved in the interplay with vision, and what is its neural basis? The hope is that this work will open the door to pain investigations into the world of sensory loss, left unexplained for too long."
|Contact: Terry Materese|
Elsevier Health Sciences