Message Number: FHL3910 | New FHL Archives SearchFrom: Sukie Crandall
Date: Sun, 10 Feb 2008 00:26:12 -0500
To: ferrethealth@yahoogroups.com
Subject: [ferrethealth] abstracts
> J Acoust Soc Am. 2008 Feb;123(2):899-909.
> Phoneme representation and classification in primary auditory cortex.
>
> Mesgarani N, David SV, Fritz JB, Shamma SA.
> Electrical and Computer Engineering & Institute for Systems
> Research, University of Maryland, College Park, Maryland 20742, USA.
> A controversial issue in neurolinguistics is whether basic neural
> auditory representations found in many animals can account for human
> perception of speech. This question was addressed by examining how a
> population of neurons in the primary auditory cortex (A1) of the
> naive awake ferret encodes phonemes and whether this representation
> could account for the human ability to discriminate them. When
> neural responses were characterized and ordered by spectral tuning
> and dynamics, perceptually significant features including formant
> patterns in vowels and place and manner of articulation in
> consonants, were readily visualized by activity in distinct neural
> subpopulations. Furthermore, these responses faithfully encoded the
> similarity between the acoustic features of these phonemes. A simple
> classifier trained on the neural representation was able to simulate
> human phoneme confusion when tested with novel exemplars. These
> results suggest that A1 responses are sufficiently rich to encode
> and discriminate phoneme classes and that humans and animals may
> build upon the same general acoustic representations to learn
> boundaries for categorical and robust sound classification.
> PMID: 18247893 [PubMed - in process]
>
> Am J Physiol Gastrointest Liver Physiol. 2008 Feb 7 [Epub ahead of
> print]
> Opioid modulation of ferret vagal afferent mechanosensitivity.
>
> Page AJ, O'Donnell TA, Blackshaw LA.
> Nerve Gut Research Laboratory, Royal Adelaide Hospital, Adelaide,
> South Australia, Australia.
> Despite universal use of opioids in the clinic to inhibit pain,
> there is relatively little known of their peripheral actions on
> sensory nerve endings, where in fact they may be better targeted
> with more widespread applications. Here we show differential effects
> of mu, kappa and delta opioids on mechanosensitive ferret esophageal
> vagal afferent endings investigated in vitro. The effects of
> selective agonists DAMGO, ICI 199441 and SNC 80 respectively on
> mechanosensory stimulus-response functions were quantified. DAMGO
> (10(-7) - 10(-5)M) reduced the responses of tension receptors to
> circumferential tension (1-5g) by up to 50%, and the responses of
> mucosal receptors to mucosal stroking (10-1000mg von Frey hair) by
> >50%. DAMGO effects were reversed by naloxone (10(-5)M). Tension/
> mucosal (TM) receptor responses to tension and stroking were
> unaffected by DAMGO. ICI 199441 (10(-6) - 10(-5)M) potently
> inhibited all responses except TM receptor responses to tension, and
> SNC 80 (10(-5) - 10(-3)M) had no effect other than a minor
> inhibition of mucosal receptor responses to intense stimuli at
> 10(-3)M. We conclude that mu- and kappa- opioids have potent and
> selective peripheral effects on esophageal vagal afferents which may
> have applications in treatment of disorders of visceral sensation.
> Key words: vagal afferents, neuromodulation, opioid receptors.
> PMID: 18258789 [PubMed - as supplied by publisher]
>
Sukie (not a vet)
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