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08-9 פיסיולוגיה מורחב. Somatosensory System and Pain. lecture 3: The primary somatosensory neuron. Prof. Marshall Devor, Ph.D. Dept. of Cell & Animal Biology and Center for Research on Pain Institute of Life Sciences Hebrew University of Jerusalem. primary sensory neuron.
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08-9 פיסיולוגיה מורחב Somatosensory System and Pain lecture 3: The primary somatosensory neuron Prof. Marshall Devor, Ph.D. Dept. of Cell & Animal Biology and Center for Research on Pain Institute of Life Sciences Hebrew University of Jerusalem
primary sensory neuron
from stimulus to impulse train…variety • 1. force transmission • to sensory ending • transduction • spike encoding
primary sensory neuron
neural crest neural crest
bipolar pseudounipolar Primary sensory neurons are pseudounipolar growth cone sensory ending
A A C
CGRPpeptide neurotransmitter RT97neurofilament 100 uM
Theory of "target derived neurotrophism"
microvilli on DRG somata • enlarged surface area • numerous neurotransmitter • and other receptor types
primary sensory neurons
epineurial blood vessel axon perineurium endoneurium skin nerve muscle nerve m/sec A, A Ia, Ib, II 15-100+ A III 2-15 C (Remak bundle) IV 0.2-2
Schwann cell soma nodal gap 2 um node of Ranvier paranode 1-2 mm internode
myelin formation Schwann cell (glia) internode 1-2 mm node of Ranvier 1-2 um 30 um
myelin formation axon, myelin, Schwann cell, oligodendroglia
myelin formation in the CNS Schwann cell vs. oligodendroglial cell
contactin associated protein
adult: DRG neuron phenotype depends on regulation of both expression and traffic of molecules of excitability (NTs)
variety of primary afferent neurons (stimulus encoding) A: LTMs: SA, RA, PC, hair A: warming, cooling, down hair, mechano-nociceptors C: mechanical nociceptors mechano-heat nociceptors CMH polymodal nociceptors silent nociceptors
“neuronal phenotype”(correlates of sensory receptor types) DRG peptides: SP, CGRP, NPY, NT, VIP, SOM, GAL, CCK… substance P, calcitonin gene related peptide….
“neuronal phenotype” (correlates of sensory receptor types) DRG peptides: SP, CGRP, NPY, NT, VIP, SOM, GAL, CCK…
פיסיולוגיה מורחב Somatosensory System and Pain lecture 3: The primary sensory neuron Prof. Marshall Devor, Ph.D. Dept. of Cell & Animal Biology and Center for Research on Pain Institute of Life Sciences Hebrew University of Jerusalem
spike invasion and the safety of through-conduction in DRG neurons …. why are DRG neurons excitable ?
somatic through-conduction spike invasion NEURON simulation Conclusion: spike invasion is a design feature of DRG neurons… but to what end ??