"Chronic pain is in many ways a central sensitization of pain producing pathways in the brain, " says James Rainville, a Harvard prof and chief of physical rehabilitation at New England Baptist Hospital.

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Since substance P is activated in response to noxious stimuli, scientists long thought that it might be a central messenger for pain.

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The drug discovery company develops therapeutic treatments for central nervous system disorders, pain, cancer and addictions.

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The suicide of 77-year-old retired pharmacist Dimitris Christoulas in April, in central Athens' Syntagma Square, also underscored the pain of the austerity measures.

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But Germany and the European Central Bank disagree over whether and how private creditors should share the pain.

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It has resisted immediately imposing losses on bondholders, yet insists they must share the pain from 2013 and has started to discuss lengthening debt maturities despite fierce resistance from the European Central Bank.

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The central banks' credibility depends on being prepared to do two unpopular things: raising interest rates, despite the economic pain, and letting financial institutions fail.

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