Nature neuroscience
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Nature neuroscience · Sep 2002
Unmyelinated tactile afferents signal touch and project to insular cortex.
There is dual tactile innervation of the human hairy skin: in addition to fast-conducting myelinated afferent fibers, there is a system of slow-conducting unmyelinated (C) afferents that respond to light touch. In a unique patient lacking large myelinated afferents, we found that activation of C tactile (CT) afferents produced a faint sensation of pleasant touch. Functional magnetic resonance imaging (fMRI) analysis during CT stimulation showed activation of the insular region, but not of somatosensory areas S1 and S2. These findings identify CT as a system for limbic touch that may underlie emotional, hormonal and affiliative responses to caress-like, skin-to-skin contact between individuals.
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Although neuroimaging studies confirm the frontal lobe's involvement in language processes and auditory working memory, the cellular and network basis of these functions is unclear. Physiological studies of the frontal lobe in non-human primates have focused on visual working memory and auditory spatial processing in dorsolateral prefrontal cortex (PFC), although the candidate PFC areas for non-spatial acoustic processing lie in the ventrolateral PFC (areas 12 and 45), which receives afferents from physiologically and anatomically defined auditory cortex. We recorded neuronal responses from ventrolateral PFC to auditory cues in awake monkeys under controlled conditions and report that the macaque ventrolateral PFC contains an auditory responsive domain in which neurons show responses to complex sounds, including animal and human vocalizations.
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Nature neuroscience · Sep 2001
Two new classes of conopeptides inhibit the alpha1-adrenoceptor and noradrenaline transporter.
Cone snails use venom containing a cocktail of peptides ('conopeptides') to capture their prey. Many of these peptides also target mammalian receptors, often with exquisite selectivity. ⋯ One class targets alpha1-adrenoceptors (rho-TIA from the fish-hunting Conus tulipa), and the second class targets the neuronal noradrenaline transporter (chi-MrIA and chi-MrIB from the mollusk-hunting C. marmoreus). rho-TIA and chi-MrIA selectively modulate these important membrane-bound proteins. Both peptides act as reversible non-competitive inhibitors and provide alternative avenues for the identification of inhibitor drugs.
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Nature neuroscience · Dec 2000
Benzodiazepines act on GABAA receptors via two distinct and separable mechanisms.
Benzodiazepines (BZs) act on gamma-aminobutyric acid type A (GABAA) receptors such as alpha1beta2gamma2 through key residues within the N-terminal region of alpha subunits, to render their sedative and anxiolytic actions. However, the molecular mechanisms underlying the BZs' other clinical actions are not known. ⋯ Converse mutation of the corresponding TM2 residue and a TM3 residue within rho1 subunits confers diazepam sensitivity on homo-oligomeric rho1-receptor channels that are otherwise insensitive to BZs. Thus, specific and distinct residues contribute to a previously unresolved component (micromolar) of diazepam action, indicating that diazepam can modulate the GABAA-receptor channel through two separable mechanisms.