Nature neuroscience
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Nature neuroscience · Jun 2009
Long-term plasticity of excitatory inputs to granule cells in the rat olfactory bulb.
Using two photon-guided focal stimulation, we found spike timing-dependent plasticity of proximal excitatory inputs to olfactory bulb granule cells that originated, in part, from cortical feedback projections. The protocol that potentiated proximal inputs depressed distal, dendrodendritic inputs to granule cells. Granule cell excitatory postsynaptic potentials and mitral cell inhibition were also potentiated by theta-burst stimulation. Plasticity of cortical feedback inputs to interneurons provides a mechanism for encoding information by modulating bulbar inhibition.
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Pleasant touch sensations may begin with neural coding in the periphery by specific afferents. We found that during soft brush stroking, low-threshold unmyelinated mechanoreceptors (C-tactile), but not myelinated afferents, responded most vigorously at intermediate brushing velocities (1-10 cm s(-1)), which were perceived by subjects as being the most pleasant. Our results indicate that C-tactile afferents constitute a privileged peripheral pathway for pleasant tactile stimulation that is likely to signal affiliative social body contact.
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Transient receptor potential vanilloid 1 (TRPV1) is an ion channel that is gated by noxious heat, capsaicin and other diverse stimuli. It is a nonselective cation channel that prefers Ca2+ over Na+. These permeability characteristics, as in most channels, are widely presumed to be static. ⋯ TRPV1 agonists showed different capabilities for evoking ionic selectivity changes. Furthermore, protein kinase C-dependent phosphorylation of Ser800 in the TRPV1 C terminus potentiated agonist-evoked ionic selectivity changes. Thus, the qualitative signaling properties of TRPV1 are dynamically modulated during channel activation, a process that probably shapes TRPV1 participation in pain, cytotoxicity and neurotransmitter release.