The Hopkins Pain Workgroup “Seeing Pain More Clearly” Optogentic and electrophysiological assay...
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Transcript of The Hopkins Pain Workgroup “Seeing Pain More Clearly” Optogentic and electrophysiological assay...
The Hopkins Pain Workgroup“Seeing Pain More Clearly”
Optogentic and electrophysiological assay of pain fibers in skin (mice): Michael Caterina, Xinzhong Dong ,Yun Guan, Paul Fuchs
Genetically-visualized pain fibers (mice): Xinzhong Dong, Yun Guan, Srinivasa Raja
Functional and molecular characterization of pain fibers in nonhuman primates: Xinzhong Dong, Joseph Mankowski, Matthias Ringkamp
Functional and molecular characterization of pain fibers in patients with painful peripheral neuropathy: Michael Caterina, Michael Polydefkis
Innervation of the cochlea: analogous to skin?
5
Type I afferents, large myelinated axons,95% of nerve, carry sound.
Type II afferents, small axons, 5% of nerve unmyelinated, carry ???.
Type I neuron:95% of afferentsContacts single IHC
Type II neuron:5% of afferentsContact many OHCs
Berglund and Ryugo ,1987
Cat Weisz6
Progress to date
• Type II afferents poorly driven by OHCs – so would respond only to (very) LOUD sound
• But, type II afferents also excited by ATP (involved in pain sensation in skin). ATP is released during acoustic trauma.
• Do type II afferents carry ‘ear pain’? The jury is still out.